Re: [Qemu-devel] [PATCH v2 1/1] The codes V2 for QEMU disk I/O limits.

[Marcelo Tosatti <mtosatti@redhat.com>]

On Wed, Jul 27, 2011 at 06:17:15PM +0800, Zhi Yong Wu wrote:
> >> +        wait_time = 1;
> >> +    }
> >> +
> >> +    wait_time = wait_time + (slice_time - elapsed_time);
> >> +    if (wait) {
> >> +        *wait = wait_time * BLOCK_IO_SLICE_TIME * 10 + 1;
> >> +    }
> >
> > The guest can keep submitting requests where "wait_time = 1" above,
> > and the timer will be rearmed continuously in the future.

This is wrong.

>  Can't you
> > simply arm the timer to the next slice start? _Some_ data must be
> > transfered by then, anyway (and nothing can be transfered earlier than
> > that).

This is valid.

> Sorry, i have got what you mean. Can you elaborate in more detail?

Sorry, the bug i mentioned about timer being rearmed does not exist.

But arming the timer for the last request as its done is confusing/unnecessary.

The timer processes queued requests, but the timer is armed accordingly
to the last queued request in the slice. For example, if a request is
submitted 1ms before the slice ends, the timer is armed 100ms +
(slice_time - elapsed_time) in the future.

> > Same for iops calculation below.
> >
> >> +
> >> +    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}[,...]]]
> >> --
> >> 1.7.2.3
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe kvm" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> 
> 
> 
> -- 
> Regards,
> 
> Zhi Yong Wu