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..40ab277 100644
--- a/block.c
+++ b/block.c
@@ -1026,6 +1026,7 @@ typedef struct RwCo {
     QEMUIOVector *qiov;
     bool is_write;
     int ret;
+    bool limit_skip;
 } RwCo;
 
 static void coroutine_fn bdrv_rw_co_entry(void *opaque)
@@ -1060,6 +1061,7 @@ 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);
@@ -1242,6 +1244,64 @@ 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;
+
+/* block I/O throttling */
+typedef struct CoroutineCB {
+    BlockDriverState *bs;
+    int64_t sector_num;
+    int nb_sectors;
+    QEMUIOVector *qiov;
+} CoroutineCB;
+
+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);
+    }
+}
+
 /*
  * Handle a read request in coroutine context
  */
@@ -2650,14 +2710,6 @@ 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();
@@ -2711,6 +2763,9 @@ 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..b7fbc40 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 +105,8 @@ 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);
 
+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 +196,13 @@ 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..86a355d 100644
--- a/block_int.h
+++ b/block_int.h
@@ -29,6 +29,7 @@
 #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
@@ -49,6 +50,11 @@ typedef struct AIOPool {
     BlockDriverAIOCB *free_aiocb;
 } AIOPool;
 
+typedef struct BlockIOLimit {
+    uint64_t bps[3];
+    uint64_t iops[3];
+} BlockIOLimit;
+
 struct BlockDriver {
     const char *format_name;
     int instance_size;
@@ -183,6 +189,9 @@ struct BlockDriverState {
 
     void *sync_aiocb;
 
+    BlockQueue   *block_queue;
+    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];
@@ -219,6 +228,20 @@ 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,
