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mm: enable __wb_calc_thresh to calculate dirty background threshold

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Patch series "Fix and cleanups to page-writeback", v2.

This series contains some random cleanups and a fix to correct calculation
of wb's bg_thresh in cgroup domain.  More details can be found respective
patches.


This patch (of 4):

Originally, __wb_calc_thresh always calculate wb's share of dirty
throttling threshold.  By getting thresh of wb_domain from caller,
__wb_calc_thresh could be used for both dirty throttling and dirty
background threshold.

This is a preparation to correct threshold calculation of wb in cgroup.

Link: https://lkml.kernel.org/r/20240425131724.36778-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20240425131724.36778-2-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Howard Cochran <hcochran@kernelspring.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kemeng Shi 2024-04-25 21:17:21 +08:00 committed by Andrew Morton
parent 826881a7f6
commit 13fc441284
1 changed files with 18 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
mm/page-writeback.c
View File

@ -838,13 +838,15 @@ static void mdtc_calc_avail(struct dirty_throttle_control *mdtc,
}
/**
* __wb_calc_thresh - @wb's share of dirty throttling threshold
* __wb_calc_thresh - @wb's share of dirty threshold
* @dtc: dirty_throttle_context of interest
* @thresh: dirty throttling or dirty background threshold of wb_domain in @dtc
*
* Note that balance_dirty_pages() will only seriously take it as a hard limit
* when sleeping max_pause per page is not enough to keep the dirty pages under
* control. For example, when the device is completely stalled due to some error
* conditions, or when there are 1000 dd tasks writing to a slow 10MB/s USB key.
* Note that balance_dirty_pages() will only seriously take dirty throttling
* threshold as a hard limit when sleeping max_pause per page is not enough
* to keep the dirty pages under control. For example, when the device is
* completely stalled due to some error conditions, or when there are 1000
* dd tasks writing to a slow 10MB/s USB key.
* In the other normal situations, it acts more gently by throttling the tasks
* more (rather than completely block them) when the wb dirty pages go high.
*
@ -855,19 +857,20 @@ static void mdtc_calc_avail(struct dirty_throttle_control *mdtc,
* The wb's share of dirty limit will be adapting to its throughput and
* bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set.
*
* Return: @wb's dirty limit in pages. The term "dirty" in the context of
* dirty balancing includes all PG_dirty and PG_writeback pages.
* Return: @wb's dirty limit in pages. For dirty throttling limit, the term
* "dirty" in the context of dirty balancing includes all PG_dirty and
* PG_writeback pages.
*/
static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc)
static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc,
unsigned long thresh)
{
struct wb_domain *dom = dtc_dom(dtc);
unsigned long thresh = dtc->thresh;
u64 wb_thresh;
unsigned long numerator, denominator;
unsigned long wb_min_ratio, wb_max_ratio;
/*
* Calculate this BDI's share of the thresh ratio.
* Calculate this wb's share of the thresh ratio.
*/
fprop_fraction_percpu(&dom->completions, dtc->wb_completions,
&numerator, &denominator);
@ -887,9 +890,9 @@ static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc)
unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh)
{
struct dirty_throttle_control gdtc = { GDTC_INIT(wb),
.thresh = thresh };
return __wb_calc_thresh(&gdtc);
struct dirty_throttle_control gdtc = { GDTC_INIT(wb) };
return __wb_calc_thresh(&gdtc, thresh);
}
unsigned long cgwb_calc_thresh(struct bdi_writeback *wb)
@ -908,7 +911,7 @@ unsigned long cgwb_calc_thresh(struct bdi_writeback *wb)
mdtc_calc_avail(&mdtc, filepages, headroom);
domain_dirty_limits(&mdtc);
return __wb_calc_thresh(&mdtc);
return __wb_calc_thresh(&mdtc, mdtc.thresh);
}
/*
@ -1655,7 +1658,7 @@ static inline void wb_dirty_limits(struct dirty_throttle_control *dtc)
* wb_position_ratio() will let the dirtier task progress
* at some rate <= (write_bw / 2) for bringing down wb_dirty.
*/
dtc->wb_thresh = __wb_calc_thresh(dtc);
dtc->wb_thresh = __wb_calc_thresh(dtc, dtc->thresh);
dtc->wb_bg_thresh = dtc->thresh ?
div64_u64(dtc->wb_thresh * dtc->bg_thresh, dtc->thresh) : 0;