The patch titled
Subject: mm: enable __wb_calc_thresh to calculate dirty background threshold
has been added to the -mm mm-unstable branch. Its filename is
mm-enable-__wb_calc_thresh-to-calculate-dirty-background-threshold.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-enable-__wb_calc_thresh-to-calculate-dirty-background-threshold.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Subject: mm: enable __wb_calc_thresh to calculate dirty background threshold
Date: Thu, 25 Apr 2024 21:17:21 +0800
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@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20240425131724.36778-2-shikemeng@xxxxxxxxxxxxxxx
Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Cc: Howard Cochran <hcochran@xxxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 33 ++++++++++++++++++---------------
1 file changed, 18 insertions(+), 15 deletions(-)
--- a/mm/page-writeback.c~mm-enable-__wb_calc_thresh-to-calculate-dirty-background-threshold
+++ a/mm/page-writeback.c
@@ -838,13 +838,15 @@ static void mdtc_calc_avail(struct dirty
}
/**
- * __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
* 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(st
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 bd
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(struc
* 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;
_
Patches currently in -mm which might be from shikemeng@xxxxxxxxxxxxxxx are
writeback-collect-stats-of-all-wb-of-bdi-in-bdi_debug_stats_show.patch
writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi.patch
writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi-fix.patch
writeback-add-wb_monitorpy-script-to-monitor-writeback-info-on-bdi.patch
writeback-rename-nr_reclaimable-to-nr_dirty-in-balance_dirty_pages.patch
mm-enable-__wb_calc_thresh-to-calculate-dirty-background-threshold.patch
mm-correct-calculation-of-wbs-bg_thresh-in-cgroup-domain.patch
mm-call-__wb_calc_thresh-instead-of-wb_calc_thresh-in-wb_over_bg_thresh.patch
mm-remove-stale-comment-__folio_mark_dirty.patch
