From: Tejun Heo <tj@kernel.org> To: axboe@kernel.dk Cc: linux-kernel@vger.kernel.org, jack@suse.cz, hch@infradead.org, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, vgoyal@redhat.com, lizefan@huawei.com, cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz, clm@fb.com, fengguang.wu@intel.com, david@fromorbit.com, gthelen@google.com, khlebnikov@yandex-team.ru, Tejun Heo <tj@kernel.org> Subject: [PATCH 09/19] writeback: add dirty_throttle_control->pos_ratio Date: Fri, 22 May 2015 18:23:26 -0400 [thread overview] Message-ID: <1432333416-6221-10-git-send-email-tj@kernel.org> (raw) In-Reply-To: <1432333416-6221-1-git-send-email-tj@kernel.org> wb_position_ratio() is used to calculate pos_ratio, which is used for two purposes. wb_update_dirty_ratelimit() uses it to adjust wb->[balanced_]dirty_ratelimit gradually and balance_dirty_pages() to immediately adjust dirty_ratelimit right before applying it to determine pause duration. While wb_update_dirty_ratelimit() is separately rate limited from balance_dirty_pages(), on the run where the ratelimit is updated, we end up calculating pos_ratio twice with the same parameters. This patch adds dirty_throttle_control->pos_ratio. balance_dirty_pages() calculates it once per run and wb_update_dirty_ratelimit() uses the value stored in dirty_throttle_control. This removes the duplicate calculation and also will help implementing memcg wb_domain. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> --- mm/page-writeback.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 2352c69..fcebae7 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -135,6 +135,8 @@ struct dirty_throttle_control { unsigned long wb_dirty; /* per-wb counterparts */ unsigned long wb_thresh; unsigned long wb_bg_thresh; + + unsigned long pos_ratio; }; #define GDTC_INIT(__wb) .wb = (__wb) @@ -717,7 +719,7 @@ static long long pos_ratio_polynom(unsigned long setpoint, * card's wb_dirty may rush to many times higher than wb_setpoint. * - the wb dirty thresh drops quickly due to change of JBOD workload */ -static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) +static void wb_position_ratio(struct dirty_throttle_control *dtc) { struct bdi_writeback *wb = dtc->wb; unsigned long write_bw = wb->avg_write_bandwidth; @@ -731,8 +733,10 @@ static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) long long pos_ratio; /* for scaling up/down the rate limit */ long x; + dtc->pos_ratio = 0; + if (unlikely(dtc->dirty >= limit)) - return 0; + return; /* * global setpoint @@ -770,18 +774,20 @@ static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) { long long wb_pos_ratio; - if (dtc->wb_dirty < 8) - return min_t(long long, pos_ratio * 2, - 2 << RATELIMIT_CALC_SHIFT); + if (dtc->wb_dirty < 8) { + dtc->pos_ratio = min_t(long long, pos_ratio * 2, + 2 << RATELIMIT_CALC_SHIFT); + return; + } if (dtc->wb_dirty >= wb_thresh) - return 0; + return; wb_setpoint = dirty_freerun_ceiling(wb_thresh, dtc->wb_bg_thresh); if (wb_setpoint == 0 || wb_setpoint == wb_thresh) - return 0; + return; wb_pos_ratio = pos_ratio_polynom(wb_setpoint, dtc->wb_dirty, wb_thresh); @@ -807,7 +813,8 @@ static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) * is 2. We might want to tweak this if we observe the control * system is too slow to adapt. */ - return min(pos_ratio, wb_pos_ratio); + dtc->pos_ratio = min(pos_ratio, wb_pos_ratio); + return; } /* @@ -888,7 +895,7 @@ static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) pos_ratio *= 8; } - return pos_ratio; + dtc->pos_ratio = pos_ratio; } static void wb_update_write_bandwidth(struct bdi_writeback *wb, @@ -1009,7 +1016,6 @@ static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc, unsigned long dirty_rate; unsigned long task_ratelimit; unsigned long balanced_dirty_ratelimit; - unsigned long pos_ratio; unsigned long step; unsigned long x; @@ -1019,12 +1025,11 @@ static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc, */ dirty_rate = (dirtied - wb->dirtied_stamp) * HZ / elapsed; - pos_ratio = wb_position_ratio(dtc); /* * task_ratelimit reflects each dd's dirty rate for the past 200ms. */ task_ratelimit = (u64)dirty_ratelimit * - pos_ratio >> RATELIMIT_CALC_SHIFT; + dtc->pos_ratio >> RATELIMIT_CALC_SHIFT; task_ratelimit++; /* it helps rampup dirty_ratelimit from tiny values */ /* @@ -1375,7 +1380,6 @@ static void balance_dirty_pages(struct address_space *mapping, bool dirty_exceeded = false; unsigned long task_ratelimit; unsigned long dirty_ratelimit; - unsigned long pos_ratio; struct backing_dev_info *bdi = wb->bdi; bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT; unsigned long start_time = jiffies; @@ -1433,6 +1437,9 @@ static void balance_dirty_pages(struct address_space *mapping, dirty_exceeded = (gdtc->wb_dirty > gdtc->wb_thresh) && ((gdtc->dirty > gdtc->thresh) || strictlimit); + + wb_position_ratio(gdtc); + if (dirty_exceeded && !wb->dirty_exceeded) wb->dirty_exceeded = 1; @@ -1444,8 +1451,7 @@ static void balance_dirty_pages(struct address_space *mapping, } dirty_ratelimit = wb->dirty_ratelimit; - pos_ratio = wb_position_ratio(gdtc); - task_ratelimit = ((u64)dirty_ratelimit * pos_ratio) >> + task_ratelimit = ((u64)dirty_ratelimit * gdtc->pos_ratio) >> RATELIMIT_CALC_SHIFT; max_pause = wb_max_pause(wb, gdtc->wb_dirty); min_pause = wb_min_pause(wb, max_pause, -- 2.4.0
WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj@kernel.org> To: axboe@kernel.dk Cc: linux-kernel@vger.kernel.org, jack@suse.cz, hch@infradead.org, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, vgoyal@redhat.com, lizefan@huawei.com, cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz, clm@fb.com, fengguang.wu@intel.com, david@fromorbit.com, gthelen@google.com, khlebnikov@yandex-team.ru, Tejun Heo <tj@kernel.org> Subject: [PATCH 09/19] writeback: add dirty_throttle_control->pos_ratio Date: Fri, 22 May 2015 18:23:26 -0400 [thread overview] Message-ID: <1432333416-6221-10-git-send-email-tj@kernel.org> (raw) In-Reply-To: <1432333416-6221-1-git-send-email-tj@kernel.org> wb_position_ratio() is used to calculate pos_ratio, which is used for two purposes. wb_update_dirty_ratelimit() uses it to adjust wb->[balanced_]dirty_ratelimit gradually and balance_dirty_pages() to immediately adjust dirty_ratelimit right before applying it to determine pause duration. While wb_update_dirty_ratelimit() is separately rate limited from balance_dirty_pages(), on the run where the ratelimit is updated, we end up calculating pos_ratio twice with the same parameters. This patch adds dirty_throttle_control->pos_ratio. balance_dirty_pages() calculates it once per run and wb_update_dirty_ratelimit() uses the value stored in dirty_throttle_control. This removes the duplicate calculation and also will help implementing memcg wb_domain. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Greg Thelen <gthelen@google.com> --- mm/page-writeback.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 2352c69..fcebae7 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -135,6 +135,8 @@ struct dirty_throttle_control { unsigned long wb_dirty; /* per-wb counterparts */ unsigned long wb_thresh; unsigned long wb_bg_thresh; + + unsigned long pos_ratio; }; #define GDTC_INIT(__wb) .wb = (__wb) @@ -717,7 +719,7 @@ static long long pos_ratio_polynom(unsigned long setpoint, * card's wb_dirty may rush to many times higher than wb_setpoint. * - the wb dirty thresh drops quickly due to change of JBOD workload */ -static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) +static void wb_position_ratio(struct dirty_throttle_control *dtc) { struct bdi_writeback *wb = dtc->wb; unsigned long write_bw = wb->avg_write_bandwidth; @@ -731,8 +733,10 @@ static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) long long pos_ratio; /* for scaling up/down the rate limit */ long x; + dtc->pos_ratio = 0; + if (unlikely(dtc->dirty >= limit)) - return 0; + return; /* * global setpoint @@ -770,18 +774,20 @@ static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) { long long wb_pos_ratio; - if (dtc->wb_dirty < 8) - return min_t(long long, pos_ratio * 2, - 2 << RATELIMIT_CALC_SHIFT); + if (dtc->wb_dirty < 8) { + dtc->pos_ratio = min_t(long long, pos_ratio * 2, + 2 << RATELIMIT_CALC_SHIFT); + return; + } if (dtc->wb_dirty >= wb_thresh) - return 0; + return; wb_setpoint = dirty_freerun_ceiling(wb_thresh, dtc->wb_bg_thresh); if (wb_setpoint == 0 || wb_setpoint == wb_thresh) - return 0; + return; wb_pos_ratio = pos_ratio_polynom(wb_setpoint, dtc->wb_dirty, wb_thresh); @@ -807,7 +813,8 @@ static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) * is 2. We might want to tweak this if we observe the control * system is too slow to adapt. */ - return min(pos_ratio, wb_pos_ratio); + dtc->pos_ratio = min(pos_ratio, wb_pos_ratio); + return; } /* @@ -888,7 +895,7 @@ static unsigned long wb_position_ratio(struct dirty_throttle_control *dtc) pos_ratio *= 8; } - return pos_ratio; + dtc->pos_ratio = pos_ratio; } static void wb_update_write_bandwidth(struct bdi_writeback *wb, @@ -1009,7 +1016,6 @@ static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc, unsigned long dirty_rate; unsigned long task_ratelimit; unsigned long balanced_dirty_ratelimit; - unsigned long pos_ratio; unsigned long step; unsigned long x; @@ -1019,12 +1025,11 @@ static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc, */ dirty_rate = (dirtied - wb->dirtied_stamp) * HZ / elapsed; - pos_ratio = wb_position_ratio(dtc); /* * task_ratelimit reflects each dd's dirty rate for the past 200ms. */ task_ratelimit = (u64)dirty_ratelimit * - pos_ratio >> RATELIMIT_CALC_SHIFT; + dtc->pos_ratio >> RATELIMIT_CALC_SHIFT; task_ratelimit++; /* it helps rampup dirty_ratelimit from tiny values */ /* @@ -1375,7 +1380,6 @@ static void balance_dirty_pages(struct address_space *mapping, bool dirty_exceeded = false; unsigned long task_ratelimit; unsigned long dirty_ratelimit; - unsigned long pos_ratio; struct backing_dev_info *bdi = wb->bdi; bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT; unsigned long start_time = jiffies; @@ -1433,6 +1437,9 @@ static void balance_dirty_pages(struct address_space *mapping, dirty_exceeded = (gdtc->wb_dirty > gdtc->wb_thresh) && ((gdtc->dirty > gdtc->thresh) || strictlimit); + + wb_position_ratio(gdtc); + if (dirty_exceeded && !wb->dirty_exceeded) wb->dirty_exceeded = 1; @@ -1444,8 +1451,7 @@ static void balance_dirty_pages(struct address_space *mapping, } dirty_ratelimit = wb->dirty_ratelimit; - pos_ratio = wb_position_ratio(gdtc); - task_ratelimit = ((u64)dirty_ratelimit * pos_ratio) >> + task_ratelimit = ((u64)dirty_ratelimit * gdtc->pos_ratio) >> RATELIMIT_CALC_SHIFT; max_pause = wb_max_pause(wb, gdtc->wb_dirty); min_pause = wb_min_pause(wb, max_pause, -- 2.4.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2015-05-22 22:24 UTC|newest] Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-05-22 22:23 [PATCHSET 2/3 v3 block/for-4.2/core] writeback: cgroup writeback backpressure propagation Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 01/19] memcg: make mem_cgroup_read_{stat|event}() iterate possible cpus instead of online Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 23:12 ` Johannes Weiner 2015-05-22 23:12 ` Johannes Weiner 2015-05-22 23:12 ` Johannes Weiner 2015-06-17 14:41 ` Michal Hocko 2015-06-17 14:41 ` Michal Hocko 2015-05-22 22:23 ` [PATCH 02/19] writeback: clean up wb_dirty_limit() Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 03/19] writeback: reorganize [__]wb_update_bandwidth() Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 04/19] writeback: implement wb_domain Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 05/19] writeback: move global_dirty_limit into wb_domain Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 06/19] writeback: consolidate dirty throttle parameters into dirty_throttle_control Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 07/19] writeback: add dirty_throttle_control->wb_bg_thresh Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 08/19] writeback: make __wb_calc_thresh() take dirty_throttle_control Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` Tejun Heo [this message] 2015-05-22 22:23 ` [PATCH 09/19] writeback: add dirty_throttle_control->pos_ratio Tejun Heo 2015-05-22 22:23 ` [PATCH 10/19] writeback: add dirty_throttle_control->wb_completions Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 11/19] writeback: add dirty_throttle_control->dom Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 12/19] writeback: make __wb_writeout_inc() and hard_dirty_limit() take wb_domaas a parameter Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 13/19] writeback: separate out domain_dirty_limits() Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 14/19] writeback: move over_bground_thresh() to mm/page-writeback.c Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 15/19] writeback: update wb_over_bg_thresh() to use wb_domain aware operations Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 16/19] writeback: implement memcg wb_domain Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 17/19] writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 18/19] writeback: implement memcg writeback domain based throttling Tejun Heo 2015-05-22 22:23 ` Tejun Heo 2015-05-22 22:23 ` [PATCH 19/19] mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use Tejun Heo 2015-05-22 22:23 ` Tejun Heo -- strict thread matches above, loose matches on Subject: below -- 2015-04-06 20:04 [PATCHSET 2/3 v2 block/for-4.1/core] writeback: cgroup writeback backpressure propagation Tejun Heo 2015-04-06 20:04 ` [PATCH 09/19] writeback: add dirty_throttle_control->pos_ratio Tejun Heo 2015-04-06 20:04 ` Tejun Heo
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