Patchwork [v9] block: add io throttling support

login
register
mail settings
Submitter Zhi Yong Wu
Date Oct. 27, 2011, 11:31 a.m.
Message ID <1319715066-24950-1-git-send-email-wuzhy@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/122113/
State New
Headers show

Comments

Zhi Yong Wu - Oct. 27, 2011, 11:31 a.m.
From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>

For sync and co driver API, i have not found one good way to do test, so currently i do some testing for async api. If anyone has one good way, pls let me know. thanks.

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
---
 Makefile.objs     |    2 +-
 block.c           |  546 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 block.h           |   24 +++
 block/blk-queue.c |  201 ++++++++++++++++++++
 block/blk-queue.h |   63 ++++++
 block_int.h       |   45 +++++
 blockdev.c        |   83 ++++++++
 blockdev.h        |    2 +
 hmp-commands.hx   |   15 ++
 qemu-config.c     |   24 +++
 qemu-options.hx   |    1 +
 qerror.c          |    4 +
 qerror.h          |    3 +
 qmp-commands.hx   |   53 +++++-
 14 files changed, 1041 insertions(+), 25 deletions(-)
 create mode 100644 block/blk-queue.c
 create mode 100644 block/blk-queue.h

Patch

diff --git a/Makefile.objs b/Makefile.objs
index 01587c8..98891b3 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -33,7 +33,7 @@  block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vv
 block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o
 block-nested-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
 block-nested-y += qed-check.o
-block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
+block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o blk-queue.o
 block-nested-$(CONFIG_WIN32) += raw-win32.o
 block-nested-$(CONFIG_POSIX) += raw-posix.o
 block-nested-$(CONFIG_CURL) += curl.o
diff --git a/block.c b/block.c
index 70aab63..022693f 100644
--- a/block.c
+++ b/block.c
@@ -30,6 +30,9 @@ 
 #include "qemu-objects.h"
 #include "qemu-coroutine.h"
 
+#include "qemu-timer.h"
+#include "block/blk-queue.h"
+
 #ifdef CONFIG_BSD
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -60,9 +63,11 @@  static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
                                          int64_t sector_num, int nb_sectors,
                                          QEMUIOVector *iov);
 static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
-    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
+    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
+    void *opaque, BlockAPIType co_type);
 static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
-    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
+    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
+    void *opaque, BlockAPIType co_type);
 static BlockDriverAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
                                                int64_t sector_num,
                                                QEMUIOVector *qiov,
@@ -72,6 +77,13 @@  static BlockDriverAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
                                                bool is_write);
 static void coroutine_fn bdrv_co_do_rw(void *opaque);
 
+static bool bdrv_exceed_bps_limits(BlockDriverState *bs, int nb_sectors,
+        bool is_write, double elapsed_time, uint64_t *wait);
+static bool bdrv_exceed_iops_limits(BlockDriverState *bs, bool is_write,
+        double elapsed_time, uint64_t *wait);
+static bool bdrv_exceed_io_limits(BlockDriverState *bs, int nb_sectors,
+        bool is_write, int64_t *wait);
+
 static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
     QTAILQ_HEAD_INITIALIZER(bdrv_states);
 
@@ -104,6 +116,83 @@  int is_windows_drive(const char *filename)
 }
 #endif
 
+/* throttling disk I/O limits */
+void bdrv_io_limits_disable(BlockDriverState *bs)
+{
+    bs->io_limits_enabled = false;
+
+    if (bs->block_queue) {
+        qemu_block_queue_submit(bs->block_queue, qemu_block_queue_cb);
+        qemu_del_block_queue(bs->block_queue);
+
+        bs->block_queue = NULL;
+    }
+
+    if (bs->block_timer) {
+        qemu_del_timer(bs->block_timer);
+        qemu_free_timer(bs->block_timer);
+        bs->block_timer     = NULL;
+    }
+
+    bs->slice_start   = 0;
+    bs->slice_end     = 0;
+    bs->slice_time    = 0;
+    memset(&bs->io_disps, 0, sizeof(bs->io_disps));
+}
+
+static void bdrv_block_timer(void *opaque)
+{
+    BlockDriverState *bs = opaque;
+    BlockQueue *queue    = bs->block_queue;
+
+    qemu_block_queue_submit(queue, qemu_block_queue_cb);
+}
+
+void bdrv_io_limits_enable(BlockDriverState *bs)
+{
+    bs->io_limits_enabled = true;
+    if (!bs->block_queue) {
+        bs->block_queue   = qemu_new_block_queue();
+        bs->block_timer   = qemu_new_timer_ns(vm_clock, bdrv_block_timer, bs);
+    }
+
+    bs->slice_time    = 5 * BLOCK_IO_SLICE_TIME;
+    bs->slice_start   = qemu_get_clock_ns(vm_clock);
+    bs->slice_end     = bs->slice_start + bs->slice_time;
+    memset(&bs->io_disps, 0, sizeof(bs->io_disps));
+}
+
+bool bdrv_io_limits_enabled(BlockDriverState *bs)
+{
+    BlockIOLimit *io_limits = &bs->io_limits;
+    return io_limits->bps[BLOCK_IO_LIMIT_READ]
+         || io_limits->bps[BLOCK_IO_LIMIT_WRITE]
+         || io_limits->bps[BLOCK_IO_LIMIT_TOTAL]
+         || io_limits->iops[BLOCK_IO_LIMIT_READ]
+         || io_limits->iops[BLOCK_IO_LIMIT_WRITE]
+         || io_limits->iops[BLOCK_IO_LIMIT_TOTAL];
+}
+
+static BlockQueueAIOCB *bdrv_io_limits_perform(BlockDriverState *bs,
+                       BlockRequestHandler *handler, int64_t sector_num,
+                       QEMUIOVector *qiov, int nb_sectors)
+{
+    BlockQueueAIOCB *ret = NULL;
+    int64_t wait_time = -1;
+
+    if (bdrv_exceed_io_limits(bs, nb_sectors, false, &wait_time)) {
+        ret = qemu_block_queue_enqueue(bs->block_queue, bs, handler,
+                                       sector_num, qiov,
+                                       nb_sectors, NULL, NULL);
+        if (wait_time != -1) {
+            qemu_mod_timer(bs->block_timer,
+                           wait_time + qemu_get_clock_ns(vm_clock));
+        }
+    }
+
+    return ret;
+}
+
 /* check if the path starts with "<protocol>:" */
 static int path_has_protocol(const char *path)
 {
@@ -684,6 +773,11 @@  int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
         bdrv_dev_change_media_cb(bs, true);
     }
 
+    /* throttling disk I/O limits */
+    if (bs->io_limits_enabled) {
+        bdrv_io_limits_enable(bs);
+    }
+
     return 0;
 
 unlink_and_fail:
@@ -719,6 +813,21 @@  void bdrv_close(BlockDriverState *bs)
 
         bdrv_dev_change_media_cb(bs, false);
     }
+
+    /*throttling disk I/O limits*/
+    bdrv_io_limits_disable(bs);
+
+    /* throttling disk I/O limits */
+    if (bs->block_queue) {
+        qemu_del_block_queue(bs->block_queue);
+        bs->block_queue = NULL;
+    }
+
+    if (bs->block_timer) {
+        qemu_del_timer(bs->block_timer);
+        qemu_free_timer(bs->block_timer);
+        bs->block_timer = NULL;
+    }
 }
 
 void bdrv_close_all(void)
@@ -1026,6 +1135,7 @@  typedef struct RwCo {
     QEMUIOVector *qiov;
     bool is_write;
     int ret;
+    bool limit_skip;
 } RwCo;
 
 static void coroutine_fn bdrv_rw_co_entry(void *opaque)
@@ -1034,10 +1144,12 @@  static void coroutine_fn bdrv_rw_co_entry(void *opaque)
 
     if (!rwco->is_write) {
         rwco->ret = bdrv_co_do_readv(rwco->bs, rwco->sector_num,
-                                     rwco->nb_sectors, rwco->qiov);
+                                     rwco->nb_sectors, rwco->qiov,
+                                     rwco, BDRV_API_SYNC);
     } else {
         rwco->ret = bdrv_co_do_writev(rwco->bs, rwco->sector_num,
-                                      rwco->nb_sectors, rwco->qiov);
+                                      rwco->nb_sectors, rwco->qiov,
+                                      rwco, BDRV_API_SYNC);
     }
 }
 
@@ -1060,6 +1172,7 @@  static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
         .qiov = &qiov,
         .is_write = is_write,
         .ret = NOT_DONE,
+        .limit_skip = false,
     };
 
     qemu_iovec_init_external(&qiov, &iov, 1);
@@ -1242,13 +1355,140 @@  int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset,
     return 0;
 }
 
+typedef struct BlockDriverAIOCBCoroutine {
+    BlockDriverAIOCB common;
+    BlockRequest req;
+    bool is_write;
+    QEMUBH *bh;
+    bool cb_skip;
+    bool limit_skip;
+    void *blkq_acb;
+} BlockDriverAIOCBCoroutine;
+
+static void bdrv_co_rw_bh(void *opaque)
+{
+    BlockDriverAIOCBCoroutine *acb = opaque;
+
+    acb->common.cb(acb->common.opaque, acb->req.error);
+
+    acb->blkq_acb = NULL;
+    qemu_bh_delete(acb->bh);
+    qemu_aio_release(acb);
+}
+
+/* block I/O throttling */
+typedef struct CoroutineCB {
+    BlockDriverState *bs;
+    int64_t sector_num;
+    int nb_sectors;
+    QEMUIOVector *qiov;
+} CoroutineCB;
+
+static bool bdrv_io_limits_skip_query(void *opaque,
+                                      BlockAPIType co_type) {
+    bool limit_skip;
+    RwCo *rwco;
+    BlockDriverAIOCBCoroutine *aioco;
+
+    if (co_type == BDRV_API_SYNC) {
+        rwco = opaque;
+        limit_skip = rwco->limit_skip;
+    } else if (co_type == BDRV_API_ASYNC) {
+        aioco = opaque;
+        limit_skip = aioco->limit_skip;
+    } else {
+        abort();
+    }
+
+    return limit_skip;
+}
+
+static void bdrv_io_limits_skip_set(void *opaque,
+                                    BlockAPIType co_type,
+                                    bool cb_skip,
+                                    bool limit_skip) {
+    RwCo *rwco;
+    BlockDriverAIOCBCoroutine *aioco;
+
+    if (co_type == BDRV_API_SYNC) {
+        rwco = opaque;
+        rwco->limit_skip = limit_skip;
+    } else if (co_type == BDRV_API_ASYNC) {
+        aioco = opaque;
+        aioco->cb_skip = cb_skip;
+        aioco->limit_skip = limit_skip;
+    } else {
+        abort();
+    }
+}
+
+void bdrv_io_limits_issue_request(void *opaque,
+                                  BlockAPIType co_type) {
+    BlockQueueAIOCB *blkq_acb = opaque;
+
+    if (blkq_acb->co_type == BDRV_API_CO) {
+        qemu_coroutine_enter(blkq_acb->co, blkq_acb->cocb);
+    } else {
+        CoroutineEntry *entry = NULL;
+        if (co_type == BDRV_API_SYNC) {
+            entry = bdrv_rw_co_entry;
+        } else if (co_type == BDRV_API_ASYNC) {
+            entry = bdrv_co_do_rw;
+        }
+
+        bdrv_io_limits_skip_set(blkq_acb->cocb,
+                                co_type, false, true);
+        Coroutine *co = qemu_coroutine_create(entry);
+        qemu_coroutine_enter(co, blkq_acb->cocb);
+    }
+}
+
+static int bdrv_io_limits_intercept(BlockDriverState *bs,
+    BlockRequestHandler *handler, int64_t sector_num,
+    QEMUIOVector *qiov, int nb_sectors, void *opaque, BlockAPIType co_type)
+{
+    BlockQueueAIOCB *blkq_acb = NULL;
+    BlockQueueRetType ret = BDRV_BLKQ_PASS;
+
+    blkq_acb = bdrv_io_limits_perform(bs, handler,
+                                      sector_num, qiov,
+                                      nb_sectors);
+    if (blkq_acb) {
+        blkq_acb->co_type = co_type;
+        blkq_acb->cocb = opaque;
+        if (co_type == BDRV_API_ASYNC) {
+            BlockDriverAIOCBCoroutine *aioco = opaque;
+            aioco->blkq_acb = blkq_acb;
+            aioco->cb_skip  = true;
+        } else if (co_type == BDRV_API_CO) {
+            blkq_acb->co = qemu_coroutine_self();
+        }
+
+        ret = BDRV_BLKQ_ENQ_FIRST;
+    } else {
+        if (bs->block_queue->flushing) {
+            if (bs->block_queue->limit_exceeded) {
+                ret = BDRV_BLKQ_ENQ_AGAIN;
+            } else {
+                blkq_acb = opaque;
+                bdrv_io_limits_issue_request(blkq_acb, co_type);
+                ret = BDRV_BLKQ_DEQ_PASS;
+            }
+        }
+    }
+
+    return ret;
+}
+
 /*
  * Handle a read request in coroutine context
  */
 static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
-    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
+    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
+    void *opaque, BlockAPIType co_type)
 {
     BlockDriver *drv = bs->drv;
+    int ret;
 
     if (!drv) {
         return -ENOMEDIUM;
@@ -1257,6 +1497,28 @@  static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
         return -EIO;
     }
 
+    /* throttling disk read I/O */
+    if (bs->io_limits_enabled
+        && !bdrv_io_limits_skip_query(opaque, co_type)) {
+        ret = bdrv_io_limits_intercept(bs, bdrv_co_do_readv,
+                                       sector_num, qiov,
+                                       nb_sectors, opaque, co_type);
+        switch (ret) {
+        case BDRV_BLKQ_ENQ_FIRST:
+            if (co_type == BDRV_API_SYNC) {
+                ret = NOT_DONE;
+            } else if (co_type == BDRV_API_ASYNC) {
+                ret = 0;
+            } else if (co_type == BDRV_API_CO) {
+                qemu_coroutine_yield();
+                break;
+            }
+        case BDRV_BLKQ_ENQ_AGAIN:
+        case BDRV_BLKQ_DEQ_PASS:
+            return ret;
+        }
+    }
+
     return drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
 }
 
@@ -1265,14 +1527,23 @@  int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
 {
     trace_bdrv_co_readv(bs, sector_num, nb_sectors);
 
-    return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov);
+    CoroutineCB cocb = {
+        .bs = bs,
+        .sector_num = sector_num,
+        .nb_sectors = nb_sectors,
+        .qiov = qiov,
+    };
+
+    return bdrv_co_do_readv(bs, sector_num, nb_sectors,
+                            qiov, &cocb, BDRV_API_CO);
 }
 
 /*
  * Handle a write request in coroutine context
  */
 static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
-    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
+    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
+    void *opaque, BlockAPIType co_type)
 {
     BlockDriver *drv = bs->drv;
     int ret;
@@ -1287,6 +1558,28 @@  static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
         return -EIO;
     }
 
+    /* throttling disk write I/O */
+    if (bs->io_limits_enabled
+        && !bdrv_io_limits_skip_query(opaque, co_type)) {
+        ret = bdrv_io_limits_intercept(bs, bdrv_co_do_writev,
+                                       sector_num, qiov,
+                                       nb_sectors, opaque, co_type);
+        switch (ret) {
+        case BDRV_BLKQ_ENQ_FIRST:
+            if (co_type == BDRV_API_SYNC) {
+                ret = NOT_DONE;
+            } else if (co_type == BDRV_API_ASYNC) {
+                ret = 0;
+            } else if (co_type == BDRV_API_CO) {
+                qemu_coroutine_yield();
+                break;
+            }
+        case BDRV_BLKQ_ENQ_AGAIN:
+        case BDRV_BLKQ_DEQ_PASS:
+            return ret;
+        }
+    }
+
     ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
 
     if (bs->dirty_bitmap) {
@@ -1305,7 +1598,15 @@  int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num,
 {
     trace_bdrv_co_writev(bs, sector_num, nb_sectors);
 
-    return bdrv_co_do_writev(bs, sector_num, nb_sectors, qiov);
+    CoroutineCB cocb = {
+        .bs = bs,
+        .sector_num = sector_num,
+        .nb_sectors = nb_sectors,
+        .qiov = qiov,
+    };
+
+    return bdrv_co_do_writev(bs, sector_num, nb_sectors,
+                             qiov, &cocb, BDRV_API_CO);
 }
 
 /**
@@ -1516,6 +1817,14 @@  void bdrv_get_geometry_hint(BlockDriverState *bs,
     *psecs = bs->secs;
 }
 
+/* throttling disk io limits */
+void bdrv_set_io_limits(BlockDriverState *bs,
+                            BlockIOLimit *io_limits)
+{
+    bs->io_limits = *io_limits;
+    bs->io_limits_enabled = bdrv_io_limits_enabled(bs);
+}
+
 /* Recognize floppy formats */
 typedef struct FDFormat {
     FDriveType drive;
@@ -1858,6 +2167,16 @@  static void bdrv_print_dict(QObject *obj, void *opaque)
                             qdict_get_bool(qdict, "ro"),
                             qdict_get_str(qdict, "drv"),
                             qdict_get_bool(qdict, "encrypted"));
+
+        monitor_printf(mon, " bps=%" PRId64 " bps_rd=%" PRId64
+                            " bps_wr=%" PRId64 " iops=%" PRId64
+                            " iops_rd=%" PRId64 " iops_wr=%" PRId64,
+                            qdict_get_int(qdict, "bps"),
+                            qdict_get_int(qdict, "bps_rd"),
+                            qdict_get_int(qdict, "bps_wr"),
+                            qdict_get_int(qdict, "iops"),
+                            qdict_get_int(qdict, "iops_rd"),
+                            qdict_get_int(qdict, "iops_wr"));
     } else {
         monitor_printf(mon, " [not inserted]");
     }
@@ -1908,10 +2227,22 @@  void bdrv_info(Monitor *mon, QObject **ret_data)
             QObject *obj;
 
             obj = qobject_from_jsonf("{ 'file': %s, 'ro': %i, 'drv': %s, "
-                                     "'encrypted': %i }",
+                                     "'encrypted': %i, "
+                                     "'bps': %" PRId64 ","
+                                     "'bps_rd': %" PRId64 ","
+                                     "'bps_wr': %" PRId64 ","
+                                     "'iops': %" PRId64 ","
+                                     "'iops_rd': %" PRId64 ","
+                                     "'iops_wr': %" PRId64 "}",
                                      bs->filename, bs->read_only,
                                      bs->drv->format_name,
-                                     bdrv_is_encrypted(bs));
+                                     bdrv_is_encrypted(bs),
+                                     bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL],
+                                     bs->io_limits.bps[BLOCK_IO_LIMIT_READ],
+                                     bs->io_limits.bps[BLOCK_IO_LIMIT_WRITE],
+                                     bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL],
+                                     bs->io_limits.iops[BLOCK_IO_LIMIT_READ],
+                                     bs->io_limits.iops[BLOCK_IO_LIMIT_WRITE]);
             if (bs->backing_file[0] != '\0') {
                 QDict *qdict = qobject_to_qdict(obj);
                 qdict_put(qdict, "backing_file",
@@ -2099,7 +2430,6 @@  void bdrv_debug_event(BlockDriverState *bs, BlkDebugEvent event)
     }
 
     return drv->bdrv_debug_event(bs, event);
-
 }
 
 /**************************************************************/
@@ -2564,6 +2894,170 @@  void bdrv_aio_cancel(BlockDriverAIOCB *acb)
     acb->pool->cancel(acb);
 }
 
+/* block I/O throttling */
+static bool bdrv_exceed_bps_limits(BlockDriverState *bs, int nb_sectors,
+                 bool is_write, double elapsed_time, uint64_t *wait) {
+    uint64_t bps_limit = 0;
+    double   bytes_limit, bytes_disp, bytes_res;
+    double   slice_time, wait_time;
+
+    if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]) {
+        bps_limit = bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL];
+    } else if (bs->io_limits.bps[is_write]) {
+        bps_limit = bs->io_limits.bps[is_write];
+    } else {
+        if (wait) {
+            *wait = 0;
+        }
+
+        return false;
+    }
+
+    slice_time = bs->slice_end - bs->slice_start;
+    slice_time /= (NANOSECONDS_PER_SECOND);
+    bytes_limit = bps_limit * slice_time;
+    bytes_disp  = bs->nr_bytes[is_write] - bs->io_disps.bytes[is_write];
+    if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]) {
+        bytes_disp += bs->nr_bytes[!is_write] - bs->io_disps.bytes[!is_write];
+    }
+
+    bytes_res   = (unsigned) nb_sectors * BDRV_SECTOR_SIZE;
+
+    if (bytes_disp + bytes_res <= bytes_limit) {
+        if (wait) {
+            *wait = 0;
+        }
+
+        return false;
+    }
+
+    /* Calc approx time to dispatch */
+    wait_time = (bytes_disp + bytes_res) / bps_limit - elapsed_time;
+
+    bs->slice_time = wait_time * BLOCK_IO_SLICE_TIME * 10;
+    bs->slice_end += bs->slice_time - 3 * BLOCK_IO_SLICE_TIME;
+    if (wait) {
+        *wait = wait_time * BLOCK_IO_SLICE_TIME * 10;
+    }
+
+    return true;
+}
+
+static bool bdrv_exceed_iops_limits(BlockDriverState *bs, bool is_write,
+                             double elapsed_time, uint64_t *wait) {
+    uint64_t iops_limit = 0;
+    double   ios_limit, ios_disp;
+    double   slice_time, wait_time;
+
+    if (bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) {
+        iops_limit = bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL];
+    } else if (bs->io_limits.iops[is_write]) {
+        iops_limit = bs->io_limits.iops[is_write];
+    } else {
+        if (wait) {
+            *wait = 0;
+        }
+
+        return false;
+    }
+
+    slice_time = bs->slice_end - bs->slice_start;
+    slice_time /= (NANOSECONDS_PER_SECOND);
+    ios_limit  = iops_limit * slice_time;
+    ios_disp   = bs->nr_ops[is_write] - bs->io_disps.ios[is_write];
+    if (bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) {
+        ios_disp += bs->nr_ops[!is_write] - bs->io_disps.ios[!is_write];
+    }
+
+    if (ios_disp + 1 <= ios_limit) {
+        if (wait) {
+            *wait = 0;
+        }
+
+        return false;
+    }
+
+    /* Calc approx time to dispatch */
+    wait_time = (ios_disp + 1) / iops_limit;
+    if (wait_time > elapsed_time) {
+        wait_time = wait_time - elapsed_time;
+    } else {
+        wait_time = 0;
+    }
+
+    bs->slice_time = wait_time * BLOCK_IO_SLICE_TIME * 10;
+    bs->slice_end += bs->slice_time - 3 * BLOCK_IO_SLICE_TIME;
+    if (wait) {
+        *wait = wait_time * BLOCK_IO_SLICE_TIME * 10;
+    }
+
+    return true;
+}
+
+static bool bdrv_exceed_io_limits(BlockDriverState *bs, int nb_sectors,
+                           bool is_write, int64_t *wait) {
+    int64_t  now, max_wait;
+    uint64_t bps_wait = 0, iops_wait = 0;
+    double   elapsed_time;
+    int      bps_ret, iops_ret;
+
+    now = qemu_get_clock_ns(vm_clock);
+    if ((bs->slice_start < now)
+        && (bs->slice_end > now)) {
+        bs->slice_end = now + bs->slice_time;
+    } else {
+        bs->slice_time  =  5 * BLOCK_IO_SLICE_TIME;
+        bs->slice_start = now;
+        bs->slice_end   = now + bs->slice_time;
+
+        bs->io_disps.bytes[is_write]  = bs->nr_bytes[is_write];
+        bs->io_disps.bytes[!is_write] = bs->nr_bytes[!is_write];
+
+        bs->io_disps.ios[is_write]    = bs->nr_ops[is_write];
+        bs->io_disps.ios[!is_write]   = bs->nr_ops[!is_write];
+    }
+
+    /* If a limit was exceeded, immediately queue this request */
+    if (!bs->block_queue->flushing
+        && qemu_block_queue_has_pending(bs->block_queue)) {
+        if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]
+            || bs->io_limits.bps[is_write] || bs->io_limits.iops[is_write]
+            || bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) {
+            if (wait) {
+                *wait = -1;
+            }
+
+            return true;
+        }
+    }
+
+    elapsed_time  = now - bs->slice_start;
+    elapsed_time  /= (NANOSECONDS_PER_SECOND);
+
+    bps_ret  = bdrv_exceed_bps_limits(bs, nb_sectors,
+                                      is_write, elapsed_time, &bps_wait);
+    iops_ret = bdrv_exceed_iops_limits(bs, is_write,
+                                      elapsed_time, &iops_wait);
+    if (bps_ret || iops_ret) {
+        max_wait = bps_wait > iops_wait ? bps_wait : iops_wait;
+        if (wait) {
+            *wait = max_wait;
+        }
+
+        now = qemu_get_clock_ns(vm_clock);
+        if (bs->slice_end < now + max_wait) {
+            bs->slice_end = now + max_wait;
+        }
+
+        return true;
+    }
+
+    if (wait) {
+        *wait = 0;
+    }
+
+    return false;
+}
 
 /**************************************************************/
 /* async block device emulation */
@@ -2650,17 +3144,18 @@  static BlockDriverAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
     return bdrv_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
 }
 
-
-typedef struct BlockDriverAIOCBCoroutine {
-    BlockDriverAIOCB common;
-    BlockRequest req;
-    bool is_write;
-    QEMUBH* bh;
-} BlockDriverAIOCBCoroutine;
-
 static void bdrv_aio_co_cancel_em(BlockDriverAIOCB *blockacb)
 {
     qemu_aio_flush();
+
+    BlockDriverAIOCBCoroutine *co_acb =
+            container_of(blockacb, BlockDriverAIOCBCoroutine, common);
+    if (co_acb->blkq_acb) {
+        BlockDriverAIOCB *acb_com = (BlockDriverAIOCB *)co_acb->blkq_acb;
+        assert(acb_com->bs);
+        acb_com->pool->cancel(acb_com);
+        co_acb->blkq_acb = NULL;
+    }
 }
 
 static AIOPool bdrv_em_co_aio_pool = {
@@ -2685,14 +3180,16 @@  static void coroutine_fn bdrv_co_do_rw(void *opaque)
 
     if (!acb->is_write) {
         acb->req.error = bdrv_co_do_readv(bs, acb->req.sector,
-            acb->req.nb_sectors, acb->req.qiov);
+            acb->req.nb_sectors, acb->req.qiov, acb, BDRV_API_ASYNC);
     } else {
         acb->req.error = bdrv_co_do_writev(bs, acb->req.sector,
-            acb->req.nb_sectors, acb->req.qiov);
+            acb->req.nb_sectors, acb->req.qiov, acb, BDRV_API_ASYNC);
     }
 
-    acb->bh = qemu_bh_new(bdrv_co_em_bh, acb);
-    qemu_bh_schedule(acb->bh);
+    if (!acb->cb_skip) {
+        acb->bh = qemu_bh_new(bdrv_co_rw_bh, acb);
+        qemu_bh_schedule(acb->bh);
+    }
 }
 
 static BlockDriverAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
@@ -2711,6 +3208,9 @@  static BlockDriverAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
     acb->req.nb_sectors = nb_sectors;
     acb->req.qiov = qiov;
     acb->is_write = is_write;
+    acb->blkq_acb = NULL;
+    acb->cb_skip  = false;
+    acb->limit_skip = false;
 
     co = qemu_coroutine_create(bdrv_co_do_rw);
     qemu_coroutine_enter(co, acb);
diff --git a/block.h b/block.h
index 5a042c9..1cd6b8b 100644
--- a/block.h
+++ b/block.h
@@ -82,6 +82,17 @@  typedef enum {
     BDRV_IOS_MAX
 } BlockIOStatus;
 
+/* disk I/O throttling */
+typedef enum {
+    BDRV_BLKQ_ENQ_FIRST, BDRV_BLKQ_ENQ_AGAIN, BDRV_BLKQ_DEQ_PASS,
+    BDRV_BLKQ_PASS, BDRV_IO_MAX
+} BlockQueueRetType;
+
+typedef enum {
+    BDRV_API_SYNC, BDRV_API_ASYNC, BDRV_API_CO,
+    BDRV_API_MAX
+} BlockAPIType;
+
 void bdrv_iostatus_enable(BlockDriverState *bs);
 void bdrv_iostatus_reset(BlockDriverState *bs);
 void bdrv_iostatus_disable(BlockDriverState *bs);
@@ -94,6 +105,12 @@  void bdrv_info(Monitor *mon, QObject **ret_data);
 void bdrv_stats_print(Monitor *mon, const QObject *data);
 void bdrv_info_stats(Monitor *mon, QObject **ret_data);
 
+/* disk I/O throttling */
+void bdrv_io_limits_enable(BlockDriverState *bs);
+void bdrv_io_limits_disable(BlockDriverState *bs);
+bool bdrv_io_limits_enabled(BlockDriverState *bs);
+void bdrv_io_limits_issue_request(void *opaque, BlockAPIType co_type);
+
 void bdrv_init(void);
 void bdrv_init_with_whitelist(void);
 BlockDriver *bdrv_find_protocol(const char *filename);
@@ -183,6 +200,13 @@  typedef struct BlockRequest {
     int error;
 } BlockRequest;
 
+typedef struct BlockQueueAIOCB BlockQueueAIOCB;
+
+typedef int coroutine_fn (BlockRequestHandler)(BlockDriverState *bs,
+                          int64_t sector_num, int nb_sectors,
+                          QEMUIOVector *qiov,
+                          void *opaque, BlockAPIType co_type);
+
 int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs,
     int num_reqs);
 
diff --git a/block/blk-queue.c b/block/blk-queue.c
new file mode 100644
index 0000000..04bcdac
--- /dev/null
+++ b/block/blk-queue.c
@@ -0,0 +1,201 @@ 
+/*
+ * QEMU System Emulator queue definition for block layer
+ *
+ * Copyright (c) IBM, Corp. 2011
+ *
+ * Authors:
+ *  Zhi Yong Wu  <wuzhy@linux.vnet.ibm.com>
+ *  Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/* The APIs for block request queue on qemu block layer.
+ */
+
+#include "block.h"
+#include "block_int.h"
+#include "blk-queue.h"
+#include "qemu-common.h"
+
+static void qemu_block_queue_dequeue(BlockQueue *queue,
+                                     BlockQueueAIOCB *request)
+{
+    BlockQueueAIOCB *req, *next;
+
+    assert(queue);
+    QTAILQ_FOREACH_SAFE(req, &queue->requests, entry, next) {
+        if (req == request) {
+            QTAILQ_REMOVE(&queue->requests, req, entry);
+            break;
+        }
+    }
+}
+
+void qemu_block_queue_cancel(BlockDriverAIOCB *acb)
+{
+    BlockQueueAIOCB *request = container_of(acb, BlockQueueAIOCB, common);
+
+    assert(request->common.bs->block_queue);
+    qemu_block_queue_dequeue(request->common.bs->block_queue,
+                             request);
+
+    qemu_aio_release(request);
+}
+
+static AIOPool block_queue_pool = {
+    .aiocb_size         = sizeof(struct BlockQueueAIOCB),
+    .cancel             = qemu_block_queue_cancel,
+};
+
+static void qemu_block_queue_bh(void *opaque)
+{
+    BlockQueueAIOCB *acb = opaque;
+
+    acb->co_type = BDRV_API_MAX;
+    acb->co      = NULL;
+    acb->cocb    = NULL;
+    qemu_bh_delete(acb->bh);
+    qemu_aio_release(acb);
+}
+
+void qemu_block_queue_cb(void *opaque, int ret)
+{
+    BlockQueueAIOCB *acb = opaque;
+    acb->bh = qemu_bh_new(qemu_block_queue_bh, acb);
+    qemu_bh_schedule(acb->bh);
+}
+
+BlockQueue *qemu_new_block_queue(void)
+{
+    BlockQueue *queue;
+
+    queue = g_malloc0(sizeof(BlockQueue));
+
+    QTAILQ_INIT(&queue->requests);
+
+    queue->limit_exceeded = false;
+    queue->flushing       = false;
+
+    return queue;
+}
+
+void qemu_del_block_queue(BlockQueue *queue)
+{
+    BlockQueueAIOCB *request, *next;
+
+    QTAILQ_FOREACH_SAFE(request, &queue->requests, entry, next) {
+        QTAILQ_REMOVE(&queue->requests, request, entry);
+        qemu_aio_release(request);
+    }
+
+    g_free(queue);
+}
+
+BlockQueueAIOCB *qemu_block_queue_enqueue(BlockQueue *queue,
+                        BlockDriverState *bs,
+                        BlockRequestHandler *handler,
+                        int64_t sector_num,
+                        QEMUIOVector *qiov,
+                        int nb_sectors,
+                        BlockDriverCompletionFunc *cb,
+                        void *opaque)
+{
+    BlockDriverAIOCB *acb;
+    BlockQueueAIOCB *request;
+
+    if (queue->flushing) {
+        queue->limit_exceeded = true;
+        return NULL;
+    } else {
+        acb = qemu_aio_get(&block_queue_pool, bs,
+                           cb, opaque);
+        request = container_of(acb, BlockQueueAIOCB, common);
+        request->handler    = handler;
+        request->sector_num = sector_num;
+        request->qiov       = qiov;
+        request->nb_sectors = nb_sectors;
+        request->bh         = NULL;
+        request->co_type    = BDRV_API_MAX;
+        request->co         = NULL;
+        request->cocb       = NULL;
+        QTAILQ_INSERT_TAIL(&queue->requests, request, entry);
+    }
+
+    return request;
+}
+
+static int qemu_block_queue_handler(BlockQueueAIOCB *request)
+{
+    int ret;
+
+    BlockDriverState *bs = request->common.bs;
+    assert(bs);
+
+    if (bs->io_limits_enabled) {
+        ret = request->handler(request->common.bs, request->sector_num,
+                               request->nb_sectors, request->qiov,
+                               request, request->co_type);
+    } else {
+        if (request->co_type == BDRV_API_CO) {
+            qemu_coroutine_enter(request->co, request->cocb);
+        } else {
+            printf("%s, req: %p\n", __func__, (void *)request);
+            bdrv_io_limits_issue_request(request, request->co_type);
+        }
+
+        ret = BDRV_BLKQ_DEQ_PASS;
+    }
+
+    return ret;
+}
+
+void qemu_block_queue_submit(BlockQueue *queue, BlockDriverCompletionFunc *cb)
+{
+    BlockQueueAIOCB *request;
+    queue->flushing = true;
+
+    /*QTAILQ_FOREACH_SAFE(request, &queue->requests, entry, next) {*/
+    while (!QTAILQ_EMPTY(&queue->requests)) {
+        int ret = 0;
+
+        request = QTAILQ_FIRST(&queue->requests);
+        QTAILQ_REMOVE(&queue->requests, request, entry);
+        queue->limit_exceeded = false;
+        ret = qemu_block_queue_handler(request);
+        if (ret == -EIO) {
+            cb(request, -EIO);
+            break;
+        } else if (ret == BDRV_BLKQ_ENQ_AGAIN) {
+            QTAILQ_INSERT_HEAD(&queue->requests, request, entry);
+            break;
+        } else if (ret == BDRV_BLKQ_DEQ_PASS) {
+            cb(request, 0);
+        }
+    }
+
+    printf("%s, leave\n", __func__);
+    queue->limit_exceeded = false;
+    queue->flushing       = false;
+}
+
+bool qemu_block_queue_has_pending(BlockQueue *queue)
+{
+    return !QTAILQ_EMPTY(&queue->requests);
+}
diff --git a/block/blk-queue.h b/block/blk-queue.h
new file mode 100644
index 0000000..4dd3dff
--- /dev/null
+++ b/block/blk-queue.h
@@ -0,0 +1,63 @@ 
+/*
+ * QEMU System Emulator queue declaration for block layer
+ *
+ * Copyright (c) IBM, Corp. 2011
+ *
+ * Authors:
+ *  Zhi Yong Wu  <wuzhy@linux.vnet.ibm.com>
+ *  Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef QEMU_BLOCK_QUEUE_H
+#define QEMU_BLOCK_QUEUE_H
+
+#include "block.h"
+#include "block_int.h"
+#include "qemu-queue.h"
+
+typedef struct BlockQueue {
+    QTAILQ_HEAD(requests, BlockQueueAIOCB) requests;
+    bool limit_exceeded;
+    bool flushing;
+} BlockQueue;
+
+BlockQueue *qemu_new_block_queue(void);
+
+void qemu_block_queue_cancel(BlockDriverAIOCB *acb);
+
+void qemu_del_block_queue(BlockQueue *queue);
+
+BlockQueueAIOCB *qemu_block_queue_enqueue(BlockQueue *queue,
+                        BlockDriverState *bs,
+                        BlockRequestHandler *handler,
+                        int64_t sector_num,
+                        QEMUIOVector *qiov,
+                        int nb_sectors,
+                        BlockDriverCompletionFunc *cb,
+                        void *opaque);
+
+void qemu_block_queue_submit(BlockQueue *queue, BlockDriverCompletionFunc *cb);
+
+void qemu_block_queue_cb(void *opaque, int ret);
+
+bool qemu_block_queue_has_pending(BlockQueue *queue);
+
+#endif /* QEMU_BLOCK_QUEUE_H */
diff --git a/block_int.h b/block_int.h
index dac00f5..3a4379c 100644
--- a/block_int.h
+++ b/block_int.h
@@ -29,10 +29,18 @@ 
 #include "qemu-queue.h"
 #include "qemu-coroutine.h"
 #include "qemu-timer.h"
+#include "block/blk-queue.h"
 
 #define BLOCK_FLAG_ENCRYPT	1
 #define BLOCK_FLAG_COMPAT6	4
 
+#define BLOCK_IO_LIMIT_READ     0
+#define BLOCK_IO_LIMIT_WRITE    1
+#define BLOCK_IO_LIMIT_TOTAL    2
+
+#define BLOCK_IO_SLICE_TIME     100000000
+#define NANOSECONDS_PER_SECOND  1000000000.0
+
 #define BLOCK_OPT_SIZE          "size"
 #define BLOCK_OPT_ENCRYPT       "encryption"
 #define BLOCK_OPT_COMPAT6       "compat6"
@@ -49,6 +57,16 @@  typedef struct AIOPool {
     BlockDriverAIOCB *free_aiocb;
 } AIOPool;
 
+typedef struct BlockIOLimit {
+    uint64_t bps[3];
+    uint64_t iops[3];
+} BlockIOLimit;
+
+typedef struct BlockIODisp {
+    uint64_t bytes[2];
+    uint64_t ios[2];
+} BlockIODisp;
+
 struct BlockDriver {
     const char *format_name;
     int instance_size;
@@ -183,6 +201,16 @@  struct BlockDriverState {
 
     void *sync_aiocb;
 
+    /* the time for latest disk I/O */
+    int64_t slice_time;
+    int64_t slice_start;
+    int64_t slice_end;
+    BlockIOLimit io_limits;
+    BlockIODisp  io_disps;
+    BlockQueue   *block_queue;
+    QEMUTimer    *block_timer;
+    bool         io_limits_enabled;
+
     /* I/O stats (display with "info blockstats"). */
     uint64_t nr_bytes[BDRV_MAX_IOTYPE];
     uint64_t nr_ops[BDRV_MAX_IOTYPE];
@@ -219,12 +247,29 @@  struct BlockDriverAIOCB {
     BlockDriverAIOCB *next;
 };
 
+/* block I/O throttling */
+struct BlockQueueAIOCB {
+    BlockDriverAIOCB common;
+    QTAILQ_ENTRY(BlockQueueAIOCB) entry;
+    BlockRequestHandler *handler;
+    int64_t sector_num;
+    QEMUIOVector *qiov;
+    int nb_sectors;
+    QEMUBH *bh;
+    BlockAPIType co_type;
+    void *co;
+    void *cocb;
+};
+
 void get_tmp_filename(char *filename, int size);
 
 void *qemu_aio_get(AIOPool *pool, BlockDriverState *bs,
                    BlockDriverCompletionFunc *cb, void *opaque);
 void qemu_aio_release(void *p);
 
+void bdrv_set_io_limits(BlockDriverState *bs,
+                        BlockIOLimit *io_limits);
+
 #ifdef _WIN32
 int is_windows_drive(const char *filename);
 #endif
diff --git a/blockdev.c b/blockdev.c
index 0827bf7..9eed973 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -235,6 +235,9 @@  DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
     int on_read_error, on_write_error;
     const char *devaddr;
     DriveInfo *dinfo;
+    BlockIOLimit io_limits;
+    bool bps_iol;
+    bool iops_iol;
     int snapshot = 0;
     int ret;
 
@@ -353,6 +356,32 @@  DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
         }
     }
 
+    /* disk I/O throttling */
+    io_limits.bps[BLOCK_IO_LIMIT_TOTAL]  =
+                           qemu_opt_get_number(opts, "bps", 0);
+    io_limits.bps[BLOCK_IO_LIMIT_READ]   =
+                           qemu_opt_get_number(opts, "bps_rd", 0);
+    io_limits.bps[BLOCK_IO_LIMIT_WRITE]  =
+                           qemu_opt_get_number(opts, "bps_wr", 0);
+    io_limits.iops[BLOCK_IO_LIMIT_TOTAL] =
+                           qemu_opt_get_number(opts, "iops", 0);
+    io_limits.iops[BLOCK_IO_LIMIT_READ]  =
+                           qemu_opt_get_number(opts, "iops_rd", 0);
+    io_limits.iops[BLOCK_IO_LIMIT_WRITE] =
+                           qemu_opt_get_number(opts, "iops_wr", 0);
+
+    bps_iol  = (io_limits.bps[BLOCK_IO_LIMIT_TOTAL] != 0)
+                 && ((io_limits.bps[BLOCK_IO_LIMIT_READ] != 0)
+                 || (io_limits.bps[BLOCK_IO_LIMIT_WRITE] != 0));
+    iops_iol = (io_limits.iops[BLOCK_IO_LIMIT_TOTAL] != 0)
+                 && ((io_limits.iops[BLOCK_IO_LIMIT_READ] != 0)
+                 || (io_limits.iops[BLOCK_IO_LIMIT_WRITE] != 0));
+    if (bps_iol || iops_iol) {
+        error_report("bps(iops) and bps_rd/bps_wr(iops_rd/iops_wr)"
+                     "cannot be used at the same time");
+        return NULL;
+    }
+
     on_write_error = BLOCK_ERR_STOP_ENOSPC;
     if ((buf = qemu_opt_get(opts, "werror")) != NULL) {
         if (type != IF_IDE && type != IF_SCSI && type != IF_VIRTIO && type != IF_NONE) {
@@ -460,6 +489,9 @@  DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
 
     bdrv_set_on_error(dinfo->bdrv, on_read_error, on_write_error);
 
+    /* disk I/O throttling */
+    bdrv_set_io_limits(dinfo->bdrv, &io_limits);
+
     switch(type) {
     case IF_IDE:
     case IF_SCSI:
@@ -713,6 +745,57 @@  int do_change_block(Monitor *mon, const char *device,
     return monitor_read_bdrv_key_start(mon, bs, NULL, NULL);
 }
 
+/* throttling disk I/O limits */
+int do_block_set_io_throttle(Monitor *mon,
+                       const QDict *qdict, QObject **ret_data)
+{
+    const char *devname = qdict_get_str(qdict, "device");
+    int64_t bps        = qdict_get_try_int(qdict, "bps", -1);
+    int64_t bps_rd     = qdict_get_try_int(qdict, "bps_rd", -1);
+    int64_t bps_wr     = qdict_get_try_int(qdict, "bps_wr", -1);
+    int64_t iops       = qdict_get_try_int(qdict, "iops", -1);
+    int64_t iops_rd    = qdict_get_try_int(qdict, "iops_rd", -1);
+    int64_t iops_wr    = qdict_get_try_int(qdict, "iops_wr", -1);
+    BlockDriverState *bs;
+
+    bs = bdrv_find(devname);
+    if (!bs) {
+        qerror_report(QERR_DEVICE_NOT_FOUND, devname);
+        return -1;
+    }
+
+    if ((bps == -1) || (bps_rd == -1) || (bps_wr == -1)
+        || (iops == -1) || (iops_rd == -1) || (iops_wr == -1)) {
+        qerror_report(QERR_MISSING_PARAMETER,
+                      "bps/bps_rd/bps_wr/iops/iops_rd/iops_wr");
+        return -1;
+    }
+
+    if ((bps != 0 && (bps_rd != 0  || bps_wr != 0))
+        || (iops != 0 && (iops_rd != 0 || iops_wr != 0))) {
+        qerror_report(QERR_INVALID_PARAMETER_COMBINATION);
+        return -1;
+    }
+
+    bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL] = bps;
+    bs->io_limits.bps[BLOCK_IO_LIMIT_READ]  = bps_rd;
+    bs->io_limits.bps[BLOCK_IO_LIMIT_WRITE] = bps_wr;
+    bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL] = iops;
+    bs->io_limits.iops[BLOCK_IO_LIMIT_READ]  = iops_rd;
+    bs->io_limits.iops[BLOCK_IO_LIMIT_WRITE] = iops_wr;
+    bs->slice_time = BLOCK_IO_SLICE_TIME;
+
+    if (!bs->io_limits_enabled && bdrv_io_limits_enabled(bs)) {
+        bdrv_io_limits_enable(bs);
+    } else if (bs->io_limits_enabled && !bdrv_io_limits_enabled(bs)) {
+        bdrv_io_limits_disable(bs);
+    } else {
+        qemu_mod_timer(bs->block_timer, qemu_get_clock_ns(vm_clock));
+    }
+
+    return 0;
+}
+
 int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
 {
     const char *id = qdict_get_str(qdict, "id");
diff --git a/blockdev.h b/blockdev.h
index 3587786..1b48a75 100644
--- a/blockdev.h
+++ b/blockdev.h
@@ -63,6 +63,8 @@  int do_block_set_passwd(Monitor *mon, const QDict *qdict, QObject **ret_data);
 int do_change_block(Monitor *mon, const char *device,
                     const char *filename, const char *fmt);
 int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
+int do_block_set_io_throttle(Monitor *mon,
+                             const QDict *qdict, QObject **ret_data);
 int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data);
 int do_block_resize(Monitor *mon, const QDict *qdict, QObject **ret_data);
 
diff --git a/hmp-commands.hx b/hmp-commands.hx
index ab08d58..a2fdf68 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1207,6 +1207,21 @@  ETEXI
     },
 
 STEXI
+@item block_set_io_throttle @var{device} @var{bps} @var{bps_rd} @var{bps_wr} @var{iops} @var{iops_rd} @var{iops_wr}
+@findex block_set_io_throttle
+Change I/O throttle limits for a block drive to @var{bps} @var{bps_rd} @var{bps_wr} @var{iops} @var{iops_rd} @var{iops_wr}
+ETEXI
+
+    {
+        .name       = "block_set_io_throttle",
+        .args_type  = "device:B,bps:i?,bps_rd:i?,bps_wr:i?,iops:i?,iops_rd:i?,iops_wr:i?",
+        .params     = "device [bps] [bps_rd] [bps_wr] [iops] [iops_rd] [iops_wr]",
+        .help       = "change I/O throttle limits for a block drive",
+        .user_print = monitor_user_noop,
+        .mhandler.cmd_new = do_block_set_io_throttle,
+    },
+
+STEXI
 @item block_passwd @var{device} @var{password}
 @findex block_passwd
 Set the encrypted device @var{device} password to @var{password}
diff --git a/qemu-config.c b/qemu-config.c
index 90b6b3e..5a201a4 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -85,6 +85,30 @@  static QemuOptsList qemu_drive_opts = {
             .name = "readonly",
             .type = QEMU_OPT_BOOL,
             .help = "open drive file as read-only",
+        },{
+            .name = "iops",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit total I/O operations per second",
+        },{
+            .name = "iops_rd",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit read operations per second",
+        },{
+            .name = "iops_wr",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit write operations per second",
+        },{
+            .name = "bps",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit total bytes per second",
+        },{
+            .name = "bps_rd",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit read bytes per second",
+        },{
+            .name = "bps_wr",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit write bytes per second",
         },
         { /* end of list */ }
     },
diff --git a/qemu-options.hx b/qemu-options.hx
index 5d2a776..9344316 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -136,6 +136,7 @@  DEF("drive", HAS_ARG, QEMU_OPTION_drive,
     "       [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
     "       [,serial=s][,addr=A][,id=name][,aio=threads|native]\n"
     "       [,readonly=on|off]\n"
+    "       [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]][[,iops=i]|[[,iops_rd=r][,iops_wr=w]]\n"
     "                use 'file' as a drive image\n", QEMU_ARCH_ALL)
 STEXI
 @item -drive @var{option}[,@var{option}[,@var{option}[,...]]]
diff --git a/qerror.c b/qerror.c
index 68998d4..6fe53b6 100644
--- a/qerror.c
+++ b/qerror.c
@@ -234,6 +234,10 @@  static const QErrorStringTable qerror_table[] = {
         .error_fmt = QERR_QGA_COMMAND_FAILED,
         .desc      = "Guest agent command failed, error was '%(message)'",
     },
+    {
+        .error_fmt = QERR_INVALID_PARAMETER_COMBINATION,
+        .desc      = "Invalid paramter combination",
+    },
     {}
 };
 
diff --git a/qerror.h b/qerror.h
index d4bfcfd..777a36a 100644
--- a/qerror.h
+++ b/qerror.h
@@ -198,4 +198,7 @@  QError *qobject_to_qerror(const QObject *obj);
 #define QERR_QGA_COMMAND_FAILED \
     "{ 'class': 'QgaCommandFailed', 'data': { 'message': %s } }"
 
+#define QERR_INVALID_PARAMETER_COMBINATION \
+    "{ 'class': 'InvalidParameterCombination', 'data': {} }"
+
 #endif /* QERROR_H */
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 4328e8b..6aa90b7 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -853,6 +853,44 @@  Example:
 EQMP
 
     {
+        .name       = "block_set_io_throttle",
+        .args_type  = "device:B,bps:i?,bps_rd:i?,bps_wr:i?,iops:i?,iops_rd:i?,iops_wr:i?",
+        .params     = "device [bps] [bps_rd] [bps_wr] [iops] [iops_rd] [iops_wr]",
+        .help       = "change I/O throttle limits for a block drive",
+        .user_print = monitor_user_noop,
+        .mhandler.cmd_new = do_block_set_io_throttle,
+    },
+
+SQMP
+block_set_io_throttle
+------------
+
+Change I/O throttle limits for a block drive.
+
+Arguments:
+
+- "device": device name (json-string)
+- "bps":  total throughput limit in bytes per second(json-int, optional)
+- "bps_rd":  read throughput limit in bytes per second(json-int, optional)
+- "bps_wr":  read throughput limit in bytes per second(json-int, optional)
+- "iops":  total I/O operations per second(json-int, optional)
+- "iops_rd":  read I/O operations per second(json-int, optional)
+- "iops_wr":  write I/O operations per second(json-int, optional)
+
+Example:
+
+-> { "execute": "block_set_io_throttle", "arguments": { "device": "virtio0",
+                                               "bps": "1000000",
+                                               "bps_rd": "0",
+                                               "bps_wr": "0",
+                                               "iops": "0",
+                                               "iops_rd": "0",
+                                               "iops_wr": "0" } }
+<- { "return": {} }
+
+EQMP
+
+    {
         .name       = "set_password",
         .args_type  = "protocol:s,password:s,connected:s?",
         .params     = "protocol password action-if-connected",
@@ -1154,6 +1192,13 @@  Each json-object contain the following:
                                 "tftp", "vdi", "vmdk", "vpc", "vvfat"
          - "backing_file": backing file name (json-string, optional)
          - "encrypted": true if encrypted, false otherwise (json-bool)
+         - "bps": limit total bytes per second (json-int)
+         - "bps_rd": limit read bytes per second (json-int)
+         - "bps_wr": limit write bytes per second (json-int)
+         - "iops": limit total I/O operations per second (json-int)
+         - "iops_rd": limit read operations per second (json-int)
+         - "iops_wr": limit write operations per second (json-int)
+
 - "io-status": I/O operation status, only present if the device supports it
                and the VM is configured to stop on errors. It's always reset
                to "ok" when the "cont" command is issued (json_string, optional)
@@ -1173,7 +1218,13 @@  Example:
                "ro":false,
                "drv":"qcow2",
                "encrypted":false,
-               "file":"disks/test.img"
+               "file":"disks/test.img",
+               "bps":1000000,
+               "bps_rd":0,
+               "bps_wr":0,
+               "iops":1000000,
+               "iops_rd":0,
+               "iops_wr":0,
             },
             "type":"unknown"
          },