Re: [Qemu-devel] [PATCH v1] qmp/hmp: add block_set_io_throttle and enhance query_block

[Zhi Yong Wu]

On Thu, Aug 4, 2011 at 9:07 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Thu, Aug 4, 2011 at 5:34 AM, Zhi Yong Wu <address@hidden> wrote:
>> @@ -1387,6 +1422,11 @@ void bdrv_set_io_limits(BlockDriverState *bs,
>>  {
>>     memset(&bs->io_limits, 0, sizeof(BlockIOLimit));
>>     bs->io_limits = *io_limits;
>> +    if (bdrv_io_limits_enabled(bs)) {
>> +        bs->io_limits_enabled = true;
>> +    } else {
>> +        bs->io_limits_enabled = false;
>> +    }
>
> Or in one line:
> bs->io_limits_enabled = bdrv_io_limits_enabled(bs);
nice.
>
>>  }
>>
>>  /* Recognize floppy formats */
>> @@ -1621,6 +1661,7 @@ BlockDriverState *bdrv_find(const char *name)
>>     return NULL;
>>  }
>>
>> +/* disk I/O throttling */
>
> Looks like this should not be here.\
Let me check when i will go to office next week.
>
>>  BlockDriverState *bdrv_next(BlockDriverState *bs)
>>  {
>>     if (!bs) {
>> @@ -1784,6 +1825,16 @@ 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]");
>>     }
>> @@ -1816,10 +1867,22 @@ void bdrv_info(Monitor *mon, QObject **ret_data)
>>             QDict *bs_dict = qobject_to_qdict(bs_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[2],
>> +                                     bs->io_limits.bps[0],
>> +                                     bs->io_limits.bps[1],
>> +                                     bs->io_limits.iops[2],
>> +                                     bs->io_limits.iops[0],
>> +                                     bs->io_limits.iops[1]);
>>             if (bs->backing_file[0] != '\0') {
>>                 QDict *qdict = qobject_to_qdict(obj);
>>                 qdict_put(qdict, "backing_file",
>> @@ -2307,7 +2370,7 @@ static bool bdrv_exceed_io_limits(BlockDriverState 
>> *bs, int nb_sectors,
>>     }
>>
>>     /* If a limit was exceeded, immediately queue this request */
>> -    if ((bs->req_from_queue == false)
>> +    if (!bs->req_from_queue
>>         && !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]
>> @@ -2362,14 +2425,14 @@ BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState 
>> *bs, int64_t sector_num,
>>     trace_bdrv_aio_readv(bs, sector_num, nb_sectors, opaque);
>>
>>     if (!drv || bdrv_check_request(bs, sector_num, nb_sectors)) {
>> -        if (bdrv_io_limits_enable(&bs->io_limits)) {
>> +        if (bs->io_limits_enabled) {
>>             bs->req_from_queue = false;
>>         }
>>         return NULL;
>>     }
>>
>>     /* throttling disk read I/O */
>> -    if (bdrv_io_limits_enable(&bs->io_limits)) {
>> +    if (bs->io_limits_enabled) {
>>         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);
>> @@ -2388,14 +2451,14 @@ BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState 
>> *bs, int64_t sector_num,
>>        bs->rd_bytes += (unsigned) nb_sectors * BDRV_SECTOR_SIZE;
>>        bs->rd_ops ++;
>>
>> -        if (bdrv_io_limits_enable(&bs->io_limits)) {
>> +        if (bs->io_limits_enabled) {
>>             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)) {
>> +    if (bs->io_limits_enabled) {
>>         bs->req_from_queue = false;
>>     }
>>
>> @@ -2451,7 +2514,7 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState 
>> *bs, int64_t sector_num,
>>
>>     if (!drv || bs->read_only
>>         || bdrv_check_request(bs, sector_num, nb_sectors)) {
>> -        if (bdrv_io_limits_enable(&bs->io_limits)) {
>> +        if (bs->io_limits_enabled) {
>>             bs->req_from_queue = false;
>>         }
>>
>> @@ -2466,7 +2529,7 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState 
>> *bs, int64_t sector_num,
>>     }
>>
>>     /* throttling disk write I/O */
>> -    if (bdrv_io_limits_enable(&bs->io_limits)) {
>> +    if (bs->io_limits_enabled) {
>>         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);
>> @@ -2488,14 +2551,14 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState 
>> *bs, int64_t sector_num,
>>             bs->wr_highest_sector = sector_num + nb_sectors - 1;
>>         }
>>
>> -        if (bdrv_io_limits_enable(&bs->io_limits)) {
>> +        if (bs->io_limits_enabled) {
>>             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)) {
>> +    if (bs->io_limits_enabled) {
>>         bs->req_from_queue = false;
>>     }
>>
>> diff --git a/block.h b/block.h
>> index f0dac62..97d2177 100644
>> --- a/block.h
>> +++ b/block.h
>> @@ -57,6 +57,11 @@ 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_res_init(BlockDriverState *bs);
>> +void bdrv_io_limits_res_deinit(BlockDriverState *bs);
>> +bool bdrv_io_limits_enabled(BlockDriverState *bs);
>> +
>>  void bdrv_init(void);
>>  void bdrv_init_with_whitelist(void);
>>  BlockDriver *bdrv_find_protocol(const char *filename);
>> diff --git a/block_int.h b/block_int.h
>> index 1ca826b..7c96094 100644
>> --- a/block_int.h
>> +++ b/block_int.h
>> @@ -199,6 +199,8 @@ struct BlockDriverState {
>>     BlockIODisp  io_disps;
>>     BlockQueue   *block_queue;
>>     QEMUTimer    *block_timer;
>> +    bool         io_limits_enabled;
>> +    bool         io_unlimit;
>>     bool         req_from_queue;
>>
>>     /* I/O stats (display with "info blockstats"). */
>> diff --git a/blockdev.c b/blockdev.c
>> index aff6bb2..dc2e8a9 100644
>> --- a/blockdev.c
>> +++ b/blockdev.c
>> @@ -376,7 +376,7 @@ DriveInfo *drive_init(QemuOpts *opts, int 
>> default_to_scsi)
>>         return NULL;
>>     }
>>
>> -    /* disk io limits */
>> +    /* disk io throttling */
>>     iol_flag = qemu_opt_io_limits_enable_flag(opts, iol_opts);
>>     if (iol_flag) {
>>         memset(&io_limits, 0, sizeof(BlockIOLimit));
>> @@ -387,6 +387,14 @@ DriveInfo *drive_init(QemuOpts *opts, int 
>> default_to_scsi)
>>         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);
>> +
>> +        if (((io_limits.bps[2] != 0)
>> +            && ((io_limits.bps[0] != 0) || (io_limits.bps[1] != 0)))
>> +            || ((io_limits.iops[2] != 0)
>> +            && ((io_limits.iops[0] != 0) || (io_limits.iops[1] != 0)))) {
>
> Please define constants for read/write/total instead of using magic numbers.
They have been defined. OK. let me replace those magic numbers with them.
>
>> +            error_report("Some params for io throttling can not coexist");
>
> This error message is vague.
>
> "bps and bps_rd/bps_wr cannot be used at the same time"
>
>> +            return NULL;
>> +        }
>>     }
>>
>>     on_write_error = BLOCK_ERR_STOP_ENOSPC;
>> @@ -765,6 +773,82 @@ 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");
>> +    uint64_t bps        = qdict_get_try_int(qdict, "bps", -1);
>> +    uint64_t bps_rd     = qdict_get_try_int(qdict, "bps_rd", -1);
>> +    uint64_t bps_wr     = qdict_get_try_int(qdict, "bps_wr", -1);
>> +    uint64_t iops       = qdict_get_try_int(qdict, "iops", -1);
>> +    uint64_t iops_rd    = qdict_get_try_int(qdict, "iops_rd", -1);
>> +    uint64_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 (devname && (bps == -1) && (bps_rd == -1) && (bps_wr == -1)
>> +        && (iops == -1) && (iops_rd == -1) && (iops_wr == -1)) {
>
> No need for the devname check.  It must be non-NULL since it is a
> mandatory argument, also bdrv_find() would have crashed since devname
> is used unchecked.
OK. i will remove devname.
>
>> +        qerror_report(QERR_IO_THROTTLE_NO_PARAM);
>> +        return -1;
>> +    }
>> +
>> +    if (((bps != -1) && ((bps_rd != -1) || (bps_wr != -1)))
>> +        || ((iops != -1) && ((iops_rd != -1) || (iops_wr != -1)))) {
>> +        qerror_report(QERR_IO_THROTTLE_PARAM_ERROR);
>> +        return -1;
>> +    }
>> +
>> +    if (bps != -1) {
>> +        bs->io_limits.bps[2] = bps;
>> +        bs->io_limits.bps[0] = 0;
>> +        bs->io_limits.bps[1] = 0;
>> +    }
>> +
>> +    if ((bps_rd != -1) || (bps_wr != -1)) {
>> +        bs->io_limits.bps[0]  = (bps_rd == -1) ? bs->io_limits.bps[0] : 
>> bps_rd;
>> +        bs->io_limits.bps[1]  = (bps_wr == -1) ? bs->io_limits.bps[1] : 
>> bps_wr;
>> +        bs->io_limits.bps[2]  = 0;
>> +    }
>> +
>> +    if (iops != -1) {
>> +        bs->io_limits.iops[2] = iops;
>> +        bs->io_limits.iops[0] = 0;
>> +        bs->io_limits.iops[1] = 0;
>> +    }
>> +
>> +    if ((iops_rd != -1) || (iops_wr != -1)) {
>> +        bs->io_limits.iops[0] =
>> +                      (iops_rd == -1) ? bs->io_limits.iops[0] : iops_rd;
>> +        bs->io_limits.iops[1] =
>> +                      (iops_wr == -1) ? bs->io_limits.iops[1] : iops_wr;
>> +        bs->io_limits.iops[2] = 0;
>> +    }
>> +
>> +    if (bdrv_io_limits_enabled(bs)) {
>> +        if (!bs->io_limits_enabled) {
>> +            bdrv_io_limits_res_init(bs);
>> +        }
>> +    } else {
>> +        if (bs->io_limits_enabled) {
>> +            BlockQueue *queue = bs->block_queue;
>> +            if (!QTAILQ_EMPTY(&queue->requests)) {
>> +                bs->io_unlimit = true;
>> +                bs->io_limits_enabled = false;
>> +            } else {
>> +                bdrv_io_limits_res_deinit(bs);
>> +            }
>> +        }
>> +    }
>
> bdrv_io_limits_res_init() and bdrv_io_limits_res_deinit() are
> basically enable/disable functions.  I would change this to:
>
> 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);
> }
Good point.
>
> And then remove the bs->io_unlimit field by immediately stopping I/O 
> throttling:
>
> void bdrv_io_limits_disable(BlockDriverState *bs)
> {
>    bs->io_limits_enabled = false;
>    bs->req_from_queue   = false;
>
>     if (bs->block_queue) {
>        qemu_block_queue_flush(bs->block_queue); /* <--- dispatch
> queued requests */
>         qemu_del_block_queue(bs->block_queue);
>     }
>
>     if (bs->block_timer) {
>         qemu_del_timer(bs->block_timer);
>         qemu_free_timer(bs->block_timer);
>     }
>
>     bs->slice_start[0]   = 0;
>     bs->slice_start[1]   = 0;
>
>     bs->slice_end[0]     = 0;
>     bs->slice_end[1]     = 0;
> }
>
> The queue flushing code from bdrv_block_timer() could be moved into
> qemu_block_queue_flush().  bdrv_block_timer() would call that function
> instead of looping over the queue itself.
OK.
>
>> +
>> +    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 0a5144c..d0d0d77 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 aceba74..3ca496d 100644
>> --- a/hmp-commands.hx
>> +++ b/hmp-commands.hx
>> @@ -1210,6 +1210,21 @@ ETEXI
>>     },
>>
>>  STEXI
>> address@hidden block_set_io_throttle @var{device} @var{bps} @var{bps_rd} 
>> @var{bps_wr} @var{iops} @var{iops_rd} @var{iops_wr}
>> address@hidden 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 limts for a block drive",
>> +        .user_print = monitor_user_noop,
>> +        .mhandler.cmd_new = do_block_set_io_throttle,
>> +    },
>> +
>> +STEXI
>> address@hidden block_passwd @var{device} @var{password}
>> address@hidden block_passwd
>>  Set the encrypted device @var{device} password to @var{password}
>> diff --git a/qerror.c b/qerror.c
>> index d7fcd93..db04df7 100644
>> --- a/qerror.c
>> +++ b/qerror.c
>> @@ -213,6 +213,14 @@ static const QErrorStringTable qerror_table[] = {
>>         .error_fmt = QERR_VNC_SERVER_FAILED,
>>         .desc      = "Could not start VNC server on %(target)",
>>     },
>> +    {
>> +        .error_fmt = QERR_IO_THROTTLE_PARAM_ERROR,
>> +        .desc      = "Some params for io throttling can not coexist",
>> +    },
>> +    {
>> +        .error_fmt = QERR_IO_THROTTLE_NO_PARAM,
>> +        .desc      = "No params for io throttling are specified",
>> +    },
>>     {}
>>  };
>>
>> diff --git a/qerror.h b/qerror.h
>> index 16c830d..892abbb 100644
>> --- a/qerror.h
>> +++ b/qerror.h
>> @@ -181,4 +181,10 @@ QError *qobject_to_qerror(const QObject *obj);
>>  #define QERR_FEATURE_DISABLED \
>>     "{ 'class': 'FeatureDisabled', 'data': { 'name': %s } }"
>>
>> +#define QERR_IO_THROTTLE_PARAM_ERROR \
>> +    "{ 'class': 'ParamsCoexistNotPermitted', 'data': {} }"
>
> This error is not specific to I/O throttling.  Please add a generic error:
>
> #define QERR_INVALID_PARAMETER_COMBINATION \
>    "{ 'class': 'InvalidParameterCombination', 'data': { 'param1': %s,
> 'param2': %s } }"
>
>> +#define QERR_IO_THROTTLE_NO_PARAM \
>> +    "{ 'class': 'NoParamsSpecified', 'data': {} }"
>
> QERR_MISSING_PARAMETER already does this.
>
>> +
>>  #endif /* QERROR_H */
>> diff --git a/qmp-commands.hx b/qmp-commands.hx
>> index 92c5c3a..0aaeae1 100644
>> --- a/qmp-commands.hx
>> +++ b/qmp-commands.hx
>> @@ -828,6 +828,44 @@ 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]",
>
> [bps]
Good catch.
>
>> +        .help       = "change I/O throttle limts 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 limts for a block drive.
>> +
>> +Arguments:
>> +
>> +- "device": device name (json-string)
>> +- "bps":  total throughput value per second(json-int, optional)
>
> Please document the units of bps ("bps" can mean bits per second or
> bytes per second):
>
> "total throughput limit in bytes per second (json-int, optional)"
OK.
>
>> +- "bps_rd":  read throughput value per second(json-int, optional)
>> +- "bps_wr":  read throughput value per second(json-int, optional)
>
> Stefan
>

Stefan, thanks for your good comments and spent time.

-- 
Regards,

Zhi Yong Wu