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 <ben...@irqsave.net>
> ---
> 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
