qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH V3 for-1.6 5/5] block: Add throttling percentage


From: Fam Zheng
Subject: Re: [Qemu-devel] [PATCH V3 for-1.6 5/5] block: Add throttling percentage metrics.
Date: Fri, 26 Jul 2013 10:55:24 +0800
User-agent: Mutt/1.5.21 (2010-09-15)

On Tue, 07/23 18:29, Benoît Canet wrote:
> This metrics show how many percent of the time I/Os are put on hold by the
> throttling algorithm.
> This metric could be used by system administrators or cloud stack developpers
> to decide when the throttling settings must be changed.
> 
> Signed-off-by: Benoit Canet <address@hidden>
> ---
>  block.c                   |   27 ++++++++++++++++++++++++++-
>  block/qapi.c              |    4 ++++
>  hmp.c                     |    6 ++++--
>  include/block/block_int.h |    2 ++
>  qapi-schema.json          |    4 +++-
>  5 files changed, 39 insertions(+), 4 deletions(-)
> 
> diff --git a/block.c b/block.c
> index bb4f8e4..6bb8570 100644
> --- a/block.c
> +++ b/block.c
> @@ -118,12 +118,21 @@ int is_windows_drive(const char *filename)
>  #endif
>  
>  /* throttling disk I/O limits */
> +static void bdrv_reset_throttling_metrics(BlockDriverState *bs)
> +{
> +    /* iddle -> reset values */
> +    bs->throttling_percentage = 0;
> +    bs->full_since = 0;
> +}
> +
>  void bdrv_io_limits_disable(BlockDriverState *bs)
>  {
>      bs->io_limits_enabled = false;
>  
>      while (qemu_co_enter_next(&bs->throttled_reqs)) {
>      }
> +
> +    bdrv_reset_throttling_metrics(bs);
>  }
>  
>  static void bdrv_make_bps_buckets_leak(BlockDriverState *bs, int64_t delta)
> @@ -213,7 +222,8 @@ static void bdrv_make_iops_buckets_leak(BlockDriverState 
> *bs, int64_t delta)
>  static void bdrv_leak_if_needed(BlockDriverState *bs)
>  {
>      int64_t now;
> -    int64_t delta;
> +    int64_t delta; /* the delta that would be ideally the timer period */
> +    int64_t delta_full; /* the delta where the bucket is full */
>  
>      if (!bs->must_leak) {
>          return;
> @@ -223,6 +233,14 @@ static void bdrv_leak_if_needed(BlockDriverState *bs)
>  
>      now = qemu_get_clock_ns(rt_clock);
>      delta = now - bs->previous_leak;
> +    /* compute throttle percentage reflecting how long IO are hold on 
> average */
> +    if (bs->full_since) {
> +        delta_full = now - bs->full_since;
> +        bs->throttling_percentage = (delta_full * 100) / delta;
> +        bs->full_since = 0;

If I understand it, the percentage is recalculated every leak check. So
it only reflects the instant io flow, instead of historical statistics?
But I think for system admin purpose, it's good to know a longer range
io activity character. Or do you think management tool should sample it?

> +    } else {
> +        bs->throttling_percentage = 0;
> +    }
>      bs->previous_leak = now;
>  
>      bdrv_make_bps_buckets_leak(bs, delta);
> @@ -260,6 +278,7 @@ static void bdrv_block_timer(void *opaque)
>      /* disable throttling time on iddle for economy purpose */
>      if (bdrv_throttling_is_iddle(bs)) {
>          bdrv_block_timer_disable(bs);
> +        bdrv_reset_throttling_metrics(bs);
>          return;
>      }
>  
> @@ -280,6 +299,7 @@ static void bdrv_block_timer_enable(BlockDriverState *bs)
>  
>      bs->block_timer = qemu_new_timer_ns(vm_clock, bdrv_block_timer, bs);
>      bs->previous_leak = qemu_get_clock_ns(rt_clock);
> +    bdrv_reset_throttling_metrics(bs);
>      qemu_mod_timer(bs->block_timer,
>                     qemu_get_clock_ns(vm_clock) +
>                     BLOCK_IO_THROTTLE_PERIOD);
> @@ -432,6 +452,11 @@ static void bdrv_io_limits_intercept(BlockDriverState 
> *bs,
>       * not full
>       */
>      while (bdrv_is_any_threshold_exceeded(bs, nb_sectors, is_write)) {
> +        /* remember since when the code decided to block the first I/O */
> +        if (qemu_co_queue_empty(&bs->throttled_reqs)) {
> +            bs->full_since = qemu_get_clock_ns(rt_clock);
> +        }
> +
>          bdrv_leak_if_needed(bs);
>          qemu_co_queue_wait_insert_head(&bs->throttled_reqs);
>          bdrv_leak_if_needed(bs);
> diff --git a/block/qapi.c b/block/qapi.c
> index f81081c..bd1c6af 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -263,6 +263,10 @@ void bdrv_query_info(BlockDriverState *bs,
>                             bs->io_limits.iops_sector_count;
>              info->inserted->iops_sector_count =
>                             bs->io_limits.iops_sector_count;
> +            info->inserted->has_throttling_percentage =
> +                           bs->throttling_percentage;
> +            info->inserted->throttling_percentage =
> +                           bs->throttling_percentage;
>          }
>  
>          bs0 = bs;
> diff --git a/hmp.c b/hmp.c
> index 3912305..9dc4862 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -348,7 +348,8 @@ void hmp_info_block(Monitor *mon, const QDict *qdict)
>                              " iops_threshold=%" PRId64
>                              " iops_rd_threshold=%" PRId64
>                              " iops_wr_threshold=%" PRId64
> -                            " iops_sector_count=%" PRId64 "\n",
> +                            " iops_sector_count=%" PRId64
> +                            " throttling_percentage=%" PRId64 "\n",
>                              info->value->inserted->bps,
>                              info->value->inserted->bps_rd,
>                              info->value->inserted->bps_wr,
> @@ -361,7 +362,8 @@ void hmp_info_block(Monitor *mon, const QDict *qdict)
>                              info->value->inserted->iops_threshold,
>                              info->value->inserted->iops_rd_threshold,
>                              info->value->inserted->iops_wr_threshold,
> -                            info->value->inserted->iops_sector_count);
> +                            info->value->inserted->iops_sector_count,
> +                            info->value->inserted->throttling_percentage);
>          } else {
>              monitor_printf(mon, " [not inserted]");
>          }
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 74d7503..4487cd9 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -271,6 +271,8 @@ struct BlockDriverState {
>      BlockIOLimit io_limits;
>      BlockIOBaseValue leaky_buckets;
>      int64_t      previous_leak;
> +    int64_t      full_since;
> +    int          throttling_percentage;
>      bool         must_leak;
>      CoQueue      throttled_reqs;
>      QEMUTimer    *block_timer;
> diff --git a/qapi-schema.json b/qapi-schema.json
> index d579fda..14a02e7 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -783,6 +783,8 @@
>  #
>  # @iops_sector_count: #optional an I/O size in sector (Since 1.6)
>  #
> +# @throttling_percentage: #optional reflect throttling activity (Since 1.6)
> +#
>  # Since: 0.14.0
>  #
>  # Notes: This interface is only found in @BlockInfo.
> @@ -797,7 +799,7 @@
>              '*bps_threshold': 'int', '*bps_rd_threshold': 'int',
>              '*bps_wr_threshold': 'int', '*iops_threshold': 'int',
>              '*iops_rd_threshold': 'int', '*iops_wr_threshold': 'int',
> -            '*iops_sector_count': 'int' } }
> +            '*iops_sector_count': 'int', '*throttling_percentage': 'int' } }
>  
>  ##
>  # @BlockDeviceIoStatus:
> -- 
> 1.7.10.4
> 
> 

-- 
Fam



reply via email to

[Prev in Thread] Current Thread [Next in Thread]