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authorLinus Torvalds <torvalds@linux-foundation.org>2016-06-11 18:42:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-06-11 18:42:59 -0700
commit8714f8f5fe396ca513ccaaac2304497439c181fb (patch)
tree080fbadd7f796cf45b514f031cd24badfb0ed8cd /mm
parent3a7c114d358dbe1c5cba70e7d4c3cb39b3c8ecaa (diff)
parentedb50a5403d2e2d2b2b63a8365c4378c9c300ed6 (diff)
Merge branch 'for-linus' of git://git.kernel.dk/linux-block
Pull block layer fixes from Jens Axboe: "A small collection of fixes for the current series. This contains: - Two fixes for xen-blkfront, from Bob Liu. - A bug fix for NVMe, releasing only the specific resources we requested. - Fix for a debugfs flags entry for nbd, from Josef. - Plug fix from Omar, fixing up a case of code being switched between two functions. - A missing bio_put() for the new discard callers of submit_bio_wait(), fixing a regression causing a leak of the bio. From Shaun. - Improve dirty limit calculation precision in the writeback code, fixing a case where setting a limit lower than 1% of memory would end up being zero. From Tejun" * 'for-linus' of git://git.kernel.dk/linux-block: NVMe: Only release requested regions xen-blkfront: fix resume issues after a migration xen-blkfront: don't call talk_to_blkback when already connected to blkback nbd: pass the nbd pointer for flags debugfs block: missing bio_put following submit_bio_wait blk-mq: really fix plug list flushing for nomerge queues writeback: use higher precision calculation in domain_dirty_limits()
Diffstat (limited to 'mm')
-rw-r--r--mm/page-writeback.c21
1 files changed, 12 insertions, 9 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b9956fdee8f5..e2481949494c 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -373,8 +373,9 @@ static void domain_dirty_limits(struct dirty_throttle_control *dtc)
struct dirty_throttle_control *gdtc = mdtc_gdtc(dtc);
unsigned long bytes = vm_dirty_bytes;
unsigned long bg_bytes = dirty_background_bytes;
- unsigned long ratio = vm_dirty_ratio;
- unsigned long bg_ratio = dirty_background_ratio;
+ /* convert ratios to per-PAGE_SIZE for higher precision */
+ unsigned long ratio = (vm_dirty_ratio * PAGE_SIZE) / 100;
+ unsigned long bg_ratio = (dirty_background_ratio * PAGE_SIZE) / 100;
unsigned long thresh;
unsigned long bg_thresh;
struct task_struct *tsk;
@@ -386,26 +387,28 @@ static void domain_dirty_limits(struct dirty_throttle_control *dtc)
/*
* The byte settings can't be applied directly to memcg
* domains. Convert them to ratios by scaling against
- * globally available memory.
+ * globally available memory. As the ratios are in
+ * per-PAGE_SIZE, they can be obtained by dividing bytes by
+ * number of pages.
*/
if (bytes)
- ratio = min(DIV_ROUND_UP(bytes, PAGE_SIZE) * 100 /
- global_avail, 100UL);
+ ratio = min(DIV_ROUND_UP(bytes, global_avail),
+ PAGE_SIZE);
if (bg_bytes)
- bg_ratio = min(DIV_ROUND_UP(bg_bytes, PAGE_SIZE) * 100 /
- global_avail, 100UL);
+ bg_ratio = min(DIV_ROUND_UP(bg_bytes, global_avail),
+ PAGE_SIZE);
bytes = bg_bytes = 0;
}
if (bytes)
thresh = DIV_ROUND_UP(bytes, PAGE_SIZE);
else
- thresh = (ratio * available_memory) / 100;
+ thresh = (ratio * available_memory) / PAGE_SIZE;
if (bg_bytes)
bg_thresh = DIV_ROUND_UP(bg_bytes, PAGE_SIZE);
else
- bg_thresh = (bg_ratio * available_memory) / 100;
+ bg_thresh = (bg_ratio * available_memory) / PAGE_SIZE;
if (bg_thresh >= thresh)
bg_thresh = thresh / 2;