Patchwork [1/1] The codes V2 for QEMU disk I/O limits.

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Submitter Zhi Yong Wu
Date July 26, 2011, 8:57 a.m.
Message ID <1311670653-20425-2-git-send-email-wuzhy@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/106799/
State New
Headers show

Comments

Zhi Yong Wu - July 26, 2011, 8:57 a.m.
Welcome to give me your comments, thanks.

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
---
 Makefile.objs     |    2 +-
 block.c           |  288 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 block.h           |    1 -
 block/blk-queue.c |  116 +++++++++++++++++++++
 block/blk-queue.h |   70 +++++++++++++
 block_int.h       |   28 +++++
 blockdev.c        |   21 ++++
 qemu-config.c     |   24 +++++
 qemu-option.c     |   17 +++
 qemu-option.h     |    1 +
 qemu-options.hx   |    1 +
 11 files changed, 559 insertions(+), 10 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 9f99ed4..06f2033 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -23,7 +23,7 @@  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 24a25d5..e54e59c 100644
--- a/block.c
+++ b/block.c
@@ -29,6 +29,9 @@ 
 #include "module.h"
 #include "qemu-objects.h"
 
+#include "qemu-timer.h"
+#include "block/blk-queue.h"
+
 #ifdef CONFIG_BSD
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -58,6 +61,13 @@  static int bdrv_read_em(BlockDriverState *bs, int64_t sector_num,
 static int bdrv_write_em(BlockDriverState *bs, int64_t sector_num,
                          const uint8_t *buf, int nb_sectors);
 
+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, uint64_t *wait);
+
 static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
     QTAILQ_HEAD_INITIALIZER(bdrv_states);
 
@@ -90,6 +100,20 @@  int is_windows_drive(const char *filename)
 }
 #endif
 
+static int bdrv_io_limits_enable(BlockIOLimit *io_limits)
+{
+    if ((io_limits->bps[0] == 0)
+         && (io_limits->bps[1] == 0)
+         && (io_limits->bps[2] == 0)
+         && (io_limits->iops[0] == 0)
+         && (io_limits->iops[1] == 0)
+         && (io_limits->iops[2] == 0)) {
+        return 0;
+    }
+
+    return 1;
+}
+
 /* check if the path starts with "<protocol>:" */
 static int path_has_protocol(const char *path)
 {
@@ -167,6 +191,28 @@  void path_combine(char *dest, int dest_size,
     }
 }
 
+static void bdrv_block_timer(void *opaque)
+{
+    BlockDriverState *bs = opaque;
+    BlockQueue *queue = bs->block_queue;
+
+    while (!QTAILQ_EMPTY(&queue->requests)) {
+        BlockIORequest *request;
+        int ret;
+
+        request = QTAILQ_FIRST(&queue->requests);
+        QTAILQ_REMOVE(&queue->requests, request, entry);
+
+        ret = qemu_block_queue_handler(request);
+        if (ret == 0) {
+            QTAILQ_INSERT_HEAD(&queue->requests, request, entry);
+            break;
+        }
+
+        qemu_free(request);
+    }
+}
+
 void bdrv_register(BlockDriver *bdrv)
 {
     if (!bdrv->bdrv_aio_readv) {
@@ -642,6 +688,15 @@  int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
             bs->change_cb(bs->change_opaque, CHANGE_MEDIA);
     }
 
+    /* throttling disk I/O limits */
+    if (bdrv_io_limits_enable(&bs->io_limits)) {
+        bs->block_queue = qemu_new_block_queue();
+        bs->block_timer = qemu_new_timer_ns(vm_clock, bdrv_block_timer, bs);
+
+        bs->slice_start[0] = qemu_get_clock_ns(vm_clock);
+        bs->slice_start[1] = qemu_get_clock_ns(vm_clock);
+    }
+
     return 0;
 
 unlink_and_fail:
@@ -680,6 +735,16 @@  void bdrv_close(BlockDriverState *bs)
         if (bs->change_cb)
             bs->change_cb(bs->change_opaque, CHANGE_MEDIA);
     }
+
+    /* throttling disk I/O limits */
+    if (bs->block_queue) {
+        qemu_del_block_queue(bs->block_queue);
+    }
+
+    if (bs->block_timer) {
+        qemu_del_timer(bs->block_timer);
+        qemu_free_timer(bs->block_timer);
+    }
 }
 
 void bdrv_close_all(void)
@@ -1312,6 +1377,14 @@  void bdrv_get_geometry_hint(BlockDriverState *bs,
     *psecs = bs->secs;
 }
 
+/* throttling disk io limits */
+void bdrv_set_io_limits(BlockDriverState *bs,
+			    BlockIOLimit *io_limits)
+{
+    memset(&bs->io_limits, 0, sizeof(BlockIOLimit));
+    bs->io_limits = *io_limits;
+}
+
 /* Recognize floppy formats */
 typedef struct FDFormat {
     FDriveType drive;
@@ -2111,6 +2184,155 @@  char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn)
     return buf;
 }
 
+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 = 0.1, 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;
+    }
+
+    bytes_limit	= bps_limit * slice_time;
+    bytes_disp  = bs->io_disps.bytes[is_write];
+    if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]) {
+        bytes_disp += 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 - bytes_limit) / bps_limit;
+    if (!wait_time) {
+        wait_time = 1;
+    }
+
+    wait_time = wait_time + (slice_time - elapsed_time);
+    if (wait) {
+        *wait = wait_time * BLOCK_IO_SLICE_TIME * 10 + 1;
+    }
+
+    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 = 0.1, 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;
+    }
+
+    ios_limit = iops_limit * slice_time;
+    ios_disp  = bs->io_disps.ios[is_write];
+    if (bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) {
+        ios_disp += 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;
+    }
+
+    if (wait) {
+        *wait = wait_time * BLOCK_IO_SLICE_TIME * 10 + 1;
+    }
+
+    return true;
+}
+
+static bool bdrv_exceed_io_limits(BlockDriverState *bs, int nb_sectors,
+                           bool is_write, uint64_t *wait) {
+    int64_t  real_time;
+    uint64_t bps_wait = 0, iops_wait = 0, max_wait;
+    double   elapsed_time;
+    int      bps_ret, iops_ret;
+
+    real_time = qemu_get_clock_ns(vm_clock);
+    if (bs->slice_start[is_write] + BLOCK_IO_SLICE_TIME <= real_time) {
+        bs->slice_start[is_write] = real_time;
+
+        bs->io_disps.bytes[is_write]   = 0;
+        bs->io_disps.bytes[!is_write]  = 0;
+
+        bs->io_disps.ios[is_write]     = 0;
+        bs->io_disps.ios[!is_write]    = 0;
+    }
+
+    /* If a limit was exceeded, immediately queue this request */
+    if ((bs->req_from_queue == false)
+        && !QTAILQ_EMPTY(&bs->block_queue->requests)) {
+        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 = 0;
+            }
+
+            return true;
+        }
+    }
+
+    elapsed_time  = real_time - bs->slice_start[is_write];
+    elapsed_time  /= (BLOCK_IO_SLICE_TIME * 10.0);
+
+    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;
+        }
+
+        return true;
+    }
+
+    if (wait) {
+        *wait = 0;
+    }
+
+    return false;
+}
 
 /**************************************************************/
 /* async I/Os */
@@ -2121,13 +2343,28 @@  BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num,
 {
     BlockDriver *drv = bs->drv;
     BlockDriverAIOCB *ret;
+    uint64_t wait_time = 0;
 
     trace_bdrv_aio_readv(bs, sector_num, nb_sectors, opaque);
 
-    if (!drv)
-        return NULL;
-    if (bdrv_check_request(bs, sector_num, nb_sectors))
+    if (!drv || bdrv_check_request(bs, sector_num, nb_sectors)) {
+        if (bdrv_io_limits_enable(&bs->io_limits)) {
+            bs->req_from_queue = false;
+        }
         return NULL;
+    }
+
+    /* throttling disk read I/O */
+    if (bdrv_io_limits_enable(&bs->io_limits)) {
+        if (bdrv_exceed_io_limits(bs, nb_sectors, false, &wait_time)) {
+            ret = qemu_block_queue_enqueue(bs->block_queue, bs, bdrv_aio_readv,
+                              sector_num, qiov, nb_sectors, cb, opaque);
+            qemu_mod_timer(bs->block_timer,
+                       wait_time + qemu_get_clock_ns(vm_clock));
+            bs->req_from_queue = false;
+            return ret;
+        }
+    }
 
     ret = drv->bdrv_aio_readv(bs, sector_num, qiov, nb_sectors,
                               cb, opaque);
@@ -2136,6 +2373,16 @@  BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num,
 	/* Update stats even though technically transfer has not happened. */
 	bs->rd_bytes += (unsigned) nb_sectors * BDRV_SECTOR_SIZE;
 	bs->rd_ops ++;
+
+        if (bdrv_io_limits_enable(&bs->io_limits)) {
+            bs->io_disps.bytes[BLOCK_IO_LIMIT_READ] +=
+                              (unsigned) nb_sectors * BDRV_SECTOR_SIZE;
+            bs->io_disps.ios[BLOCK_IO_LIMIT_READ]++;
+        }
+    }
+
+    if (bdrv_io_limits_enable(&bs->io_limits)) {
+        bs->req_from_queue = false;
     }
 
     return ret;
@@ -2184,15 +2431,18 @@  BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
     BlockDriver *drv = bs->drv;
     BlockDriverAIOCB *ret;
     BlockCompleteData *blk_cb_data;
+    uint64_t wait_time = 0;
 
     trace_bdrv_aio_writev(bs, sector_num, nb_sectors, opaque);
 
-    if (!drv)
-        return NULL;
-    if (bs->read_only)
-        return NULL;
-    if (bdrv_check_request(bs, sector_num, nb_sectors))
+    if (!drv || bs->read_only
+        || bdrv_check_request(bs, sector_num, nb_sectors)) {
+        if (bdrv_io_limits_enable(&bs->io_limits)) {
+            bs->req_from_queue = false;
+        }
+
         return NULL;
+    }
 
     if (bs->dirty_bitmap) {
         blk_cb_data = blk_dirty_cb_alloc(bs, sector_num, nb_sectors, cb,
@@ -2201,6 +2451,18 @@  BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
         opaque = blk_cb_data;
     }
 
+    /* throttling disk write I/O */
+    if (bdrv_io_limits_enable(&bs->io_limits)) {
+        if (bdrv_exceed_io_limits(bs, nb_sectors, true, &wait_time)) {
+            ret = qemu_block_queue_enqueue(bs->block_queue, bs, bdrv_aio_writev,
+                                  sector_num, qiov, nb_sectors, cb, opaque);
+            qemu_mod_timer(bs->block_timer,
+                                  wait_time + qemu_get_clock_ns(vm_clock));
+            bs->req_from_queue = false;
+            return ret;
+        }
+    }
+
     ret = drv->bdrv_aio_writev(bs, sector_num, qiov, nb_sectors,
                                cb, opaque);
 
@@ -2211,6 +2473,16 @@  BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
         if (bs->wr_highest_sector < sector_num + nb_sectors - 1) {
             bs->wr_highest_sector = sector_num + nb_sectors - 1;
         }
+
+        if (bdrv_io_limits_enable(&bs->io_limits)) {
+            bs->io_disps.bytes[BLOCK_IO_LIMIT_WRITE] +=
+                               (unsigned) nb_sectors * BDRV_SECTOR_SIZE;
+            bs->io_disps.ios[BLOCK_IO_LIMIT_WRITE]++;
+        }
+    }
+
+    if (bdrv_io_limits_enable(&bs->io_limits)) {
+        bs->req_from_queue = false;
     }
 
     return ret;
diff --git a/block.h b/block.h
index 859d1d9..f0dac62 100644
--- a/block.h
+++ b/block.h
@@ -97,7 +97,6 @@  int bdrv_change_backing_file(BlockDriverState *bs,
     const char *backing_file, const char *backing_fmt);
 void bdrv_register(BlockDriver *bdrv);
 
-
 typedef struct BdrvCheckResult {
     int corruptions;
     int leaks;
diff --git a/block/blk-queue.c b/block/blk-queue.c
new file mode 100644
index 0000000..09fcfe9
--- /dev/null
+++ b/block/blk-queue.c
@@ -0,0 +1,116 @@ 
+/*
+ * QEMU System Emulator queue definition for block layer
+ *
+ * Copyright (c) 2011 Zhi Yong Wu  <zwu.kernel@gmail.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.
+ */
+
+#include "block_int.h"
+#include "qemu-queue.h"
+#include "block/blk-queue.h"
+
+/* The APIs for block request queue on qemu block layer.
+ */
+
+static void qemu_block_queue_cancel(BlockDriverAIOCB *acb)
+{
+    qemu_aio_release(acb);
+}
+
+static AIOPool block_queue_pool = {
+    .aiocb_size         = sizeof(struct BlockDriverAIOCB),
+    .cancel             = qemu_block_queue_cancel,
+};
+
+static void qemu_block_queue_callback(void *opaque, int ret)
+{
+    BlockDriverAIOCB *acb = opaque;
+
+    qemu_aio_release(acb);
+}
+
+BlockQueue *qemu_new_block_queue(void)
+{
+    BlockQueue *queue;
+
+    queue = qemu_mallocz(sizeof(BlockQueue));
+
+    QTAILQ_INIT(&queue->requests);
+
+    return queue;
+}
+
+void qemu_del_block_queue(BlockQueue *queue)
+{
+    BlockIORequest *request, *next;
+
+    QTAILQ_FOREACH_SAFE(request, &queue->requests, entry, next) {
+        QTAILQ_REMOVE(&queue->requests, request, entry);
+        qemu_free(request);
+    }
+
+    qemu_free(queue);
+}
+
+BlockDriverAIOCB *qemu_block_queue_enqueue(BlockQueue *queue,
+			BlockDriverState *bs,
+			BlockRequestHandler *handler,
+			int64_t sector_num,
+			QEMUIOVector *qiov,
+			int nb_sectors,
+			BlockDriverCompletionFunc *cb,
+			void *opaque)
+{
+    BlockIORequest *request;
+    BlockDriverAIOCB *acb;
+
+    request = qemu_malloc(sizeof(BlockIORequest));
+    request->bs = bs;
+    request->handler = handler;
+    request->sector_num = sector_num;
+    request->qiov = qiov;
+    request->nb_sectors = nb_sectors;
+    request->cb = cb;
+    request->opaque = opaque;
+
+    QTAILQ_INSERT_TAIL(&queue->requests, request, entry);
+
+    acb = qemu_aio_get(&block_queue_pool, bs,
+                       qemu_block_queue_callback, opaque);
+
+    return acb;
+}
+
+int qemu_block_queue_handler(BlockIORequest *request)
+{
+    int ret;
+    BlockDriverAIOCB *res;
+
+    /* indicate this req is from block queue */
+    request->bs->req_from_queue = true;
+
+    res = request->handler(request->bs, request->sector_num,
+        	                request->qiov, request->nb_sectors,
+				request->cb, request->opaque);
+
+    ret = (res == NULL) ? 0 : 1; 
+
+    return ret;
+}
diff --git a/block/blk-queue.h b/block/blk-queue.h
new file mode 100644
index 0000000..47f8a36
--- /dev/null
+++ b/block/blk-queue.h
@@ -0,0 +1,70 @@ 
+/*
+ * QEMU System Emulator queue declaration for block layer
+ *
+ * Copyright (c) 2011 Zhi Yong Wu  <zwu.kernel@gmail.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 "qemu-queue.h"
+#include "qemu-common.h"
+
+typedef BlockDriverAIOCB* (BlockRequestHandler) (BlockDriverState *bs,
+                                int64_t sector_num, QEMUIOVector *qiov,
+                                int nb_sectors, BlockDriverCompletionFunc *cb,
+                                void *opaque);
+
+struct BlockIORequest {
+    QTAILQ_ENTRY(BlockIORequest) entry;
+    BlockDriverState *bs;
+    BlockRequestHandler *handler;
+    int64_t sector_num;
+    QEMUIOVector *qiov;
+    int nb_sectors;
+    BlockDriverCompletionFunc *cb;
+    void *opaque;
+};
+
+typedef struct BlockIORequest BlockIORequest;
+
+struct BlockQueue {
+    QTAILQ_HEAD(requests, BlockIORequest) requests;
+};
+
+typedef struct BlockQueue BlockQueue;
+
+BlockQueue *qemu_new_block_queue(void);
+
+void qemu_del_block_queue(BlockQueue *queue);
+
+BlockDriverAIOCB *qemu_block_queue_enqueue(BlockQueue *queue,
+                        BlockDriverState *bs,
+                        BlockRequestHandler *handler,
+                        int64_t sector_num,
+                        QEMUIOVector *qiov,
+                        int nb_sectors,
+                        BlockDriverCompletionFunc *cb,
+                        void *opaque);
+
+int qemu_block_queue_handler(BlockIORequest *request);
+#endif /* QEMU_BLOCK_QUEUE_H */
diff --git a/block_int.h b/block_int.h
index 1e265d2..1587171 100644
--- a/block_int.h
+++ b/block_int.h
@@ -27,10 +27,17 @@ 
 #include "block.h"
 #include "qemu-option.h"
 #include "qemu-queue.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 BLOCK_OPT_SIZE          "size"
 #define BLOCK_OPT_ENCRYPT       "encryption"
 #define BLOCK_OPT_COMPAT6       "compat6"
@@ -46,6 +53,16 @@  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;
@@ -175,6 +192,14 @@  struct BlockDriverState {
 
     void *sync_aiocb;
 
+    /* the time for latest disk I/O */
+    int64_t slice_start[2];
+    BlockIOLimit io_limits;
+    BlockIODisp  io_disps;
+    BlockQueue   *block_queue;
+    QEMUTimer    *block_timer;
+    bool         req_from_queue;
+
     /* I/O stats (display with "info blockstats"). */
     uint64_t rd_bytes;
     uint64_t wr_bytes;
@@ -222,6 +247,9 @@  void qemu_aio_release(void *p);
 
 void *qemu_blockalign(BlockDriverState *bs, size_t size);
 
+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 c263663..45602f4 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -238,6 +238,9 @@  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 iol_flag = false;
+    const char *iol_opts[7] = {"bps", "bps_rd", "bps_wr", "iops", "iops_rd", "iops_wr"};
     int is_extboot = 0;
     int snapshot = 0;
     int ret;
@@ -372,6 +375,19 @@  DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
         return NULL;
     }
 
+    /* disk io limits */
+    iol_flag = qemu_opt_io_limits_enable_flag(opts, iol_opts);
+    if (iol_flag) {
+        memset(&io_limits, 0, sizeof(BlockIOLimit));
+
+        io_limits.bps[2]  = qemu_opt_get_number(opts, "bps", 0);
+        io_limits.bps[0]  = qemu_opt_get_number(opts, "bps_rd", 0);
+        io_limits.bps[1]  = qemu_opt_get_number(opts, "bps_wr", 0);
+        io_limits.iops[2] = qemu_opt_get_number(opts, "iops", 0);
+        io_limits.iops[0] = qemu_opt_get_number(opts, "iops_rd", 0);
+        io_limits.iops[1] = qemu_opt_get_number(opts, "iops_wr", 0);
+    }
+
     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) {
@@ -483,6 +499,11 @@  DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
 
     bdrv_set_on_error(dinfo->bdrv, on_read_error, on_write_error);
 
+    /* throttling disk io limits */
+    if (iol_flag) {
+        bdrv_set_io_limits(dinfo->bdrv, &io_limits);
+    }
+
     switch(type) {
     case IF_IDE:
     case IF_SCSI:
diff --git a/qemu-config.c b/qemu-config.c
index efa892c..9232bbb 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -82,6 +82,30 @@  static QemuOptsList qemu_drive_opts = {
             .name = "boot",
             .type = QEMU_OPT_BOOL,
             .help = "make this a boot drive",
+        },{
+            .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-option.c b/qemu-option.c
index 65db542..9fe234d 100644
--- a/qemu-option.c
+++ b/qemu-option.c
@@ -562,6 +562,23 @@  uint64_t qemu_opt_get_number(QemuOpts *opts, const char *name, uint64_t defval)
     return opt->value.uint;
 }
 
+bool qemu_opt_io_limits_enable_flag(QemuOpts *opts, const char **iol_opts)
+{
+     int i;
+     uint64_t opt_val   = 0;
+     bool iol_flag = false;
+
+     for (i = 0; iol_opts[i]; i++) {
+	 opt_val = qemu_opt_get_number(opts, iol_opts[i], 0);
+	 if (opt_val != 0) {
+	     iol_flag = true;
+	     break;
+	 }
+     }
+
+     return iol_flag;
+}
+
 uint64_t qemu_opt_get_size(QemuOpts *opts, const char *name, uint64_t defval)
 {
     QemuOpt *opt = qemu_opt_find(opts, name);
diff --git a/qemu-option.h b/qemu-option.h
index b515813..fc909f9 100644
--- a/qemu-option.h
+++ b/qemu-option.h
@@ -107,6 +107,7 @@  struct QemuOptsList {
 const char *qemu_opt_get(QemuOpts *opts, const char *name);
 int qemu_opt_get_bool(QemuOpts *opts, const char *name, int defval);
 uint64_t qemu_opt_get_number(QemuOpts *opts, const char *name, uint64_t defval);
+bool qemu_opt_io_limits_enable_flag(QemuOpts *opts, const char **iol_opts);
 uint64_t qemu_opt_get_size(QemuOpts *opts, const char *name, uint64_t defval);
 int qemu_opt_set(QemuOpts *opts, const char *name, const char *value);
 typedef int (*qemu_opt_loopfunc)(const char *name, const char *value, void *opaque);
diff --git a/qemu-options.hx b/qemu-options.hx
index cb3347e..ae219f5 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -121,6 +121,7 @@  DEF("drive", HAS_ARG, QEMU_OPTION_drive,
     "       [,cache=writethrough|writeback|none|unsafe][,format=f]\n"
     "       [,serial=s][,addr=A][,id=name][,aio=threads|native]\n"
     "       [,readonly=on|off][,boot=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}[,...]]]