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authorLinus Torvalds <torvalds@linux-foundation.org>2020-08-07 11:39:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-07 11:39:33 -0700
commit81e11336d97e7a4c25a65c302ef2bf9cd9808ed4 (patch)
tree44e069e0bb26068137a1bda7ca5125c5b068b4ab /lib/percpu_counter.c
parent5631c5e0eb9035d92ceb20fcd9cdb7779a3f5cc7 (diff)
parent912c05720f00d039103d356a59c37dc7c3995e01 (diff)
downloadlinux-81e11336d97e7a4c25a65c302ef2bf9cd9808ed4.tar.bz2
Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton: - a few MM hotfixes - kthread, tools, scripts, ntfs and ocfs2 - some of MM Subsystems affected by this patch series: kthread, tools, scripts, ntfs, ocfs2 and mm (hofixes, pagealloc, slab-generic, slab, slub, kcsan, debug, pagecache, gup, swap, shmem, memcg, pagemap, mremap, mincore, sparsemem, vmalloc, kasan, pagealloc, hugetlb and vmscan). * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (162 commits) mm: vmscan: consistent update to pgrefill mm/vmscan.c: fix typo khugepaged: khugepaged_test_exit() check mmget_still_valid() khugepaged: retract_page_tables() remember to test exit khugepaged: collapse_pte_mapped_thp() protect the pmd lock khugepaged: collapse_pte_mapped_thp() flush the right range mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible mm: thp: replace HTTP links with HTTPS ones mm/page_alloc: fix memalloc_nocma_{save/restore} APIs mm/page_alloc.c: skip setting nodemask when we are in interrupt mm/page_alloc: fallbacks at most has 3 elements mm/page_alloc: silence a KASAN false positive mm/page_alloc.c: remove unnecessary end_bitidx for [set|get]_pfnblock_flags_mask() mm/page_alloc.c: simplify pageblock bitmap access mm/page_alloc.c: extract the common part in pfn_to_bitidx() mm/page_alloc.c: replace the definition of NR_MIGRATETYPE_BITS with PB_migratetype_bits mm/shuffle: remove dynamic reconfiguration mm/memory_hotplug: document why shuffle_zone() is relevant mm/page_alloc: remove nr_free_pagecache_pages() mm: remove vm_total_pages ...
Diffstat (limited to 'lib/percpu_counter.c')
-rw-r--r--lib/percpu_counter.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index a66595ba5543..a2345de90e93 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -99,6 +99,25 @@ void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
EXPORT_SYMBOL(percpu_counter_add_batch);
/*
+ * For percpu_counter with a big batch, the devication of its count could
+ * be big, and there is requirement to reduce the deviation, like when the
+ * counter's batch could be runtime decreased to get a better accuracy,
+ * which can be achieved by running this sync function on each CPU.
+ */
+void percpu_counter_sync(struct percpu_counter *fbc)
+{
+ unsigned long flags;
+ s64 count;
+
+ raw_spin_lock_irqsave(&fbc->lock, flags);
+ count = __this_cpu_read(*fbc->counters);
+ fbc->count += count;
+ __this_cpu_sub(*fbc->counters, count);
+ raw_spin_unlock_irqrestore(&fbc->lock, flags);
+}
+EXPORT_SYMBOL(percpu_counter_sync);
+
+/*
* Add up all the per-cpu counts, return the result. This is a more accurate
* but much slower version of percpu_counter_read_positive()
*/