Messages in this thread | | | Subject | Re: [PATCH 2/2 -mm] mm: account lazy free pages into available memory | From | Yang Shi <> | Date | Mon, 8 Jul 2019 15:53:05 -0700 |
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And how about this one?
On 6/27/19 10:12 AM, Yang Shi wrote: > Available memory is one of the most important metrics for memory > pressure. Currently, lazy free pages are not accounted into available > memory, but they are reclaimable actually, like reclaimable slabs. > > Accounting lazy free pages into available memory should reflect the real > memory pressure status, and also would help administrators and/or other > high level scheduling tools make better decision. > > The /proc/meminfo would show more available memory with test which > creates ~1GB deferred split THP. > > Before: > MemAvailable: 43544272 kB > ... > AnonHugePages: 10240 kB > ShmemHugePages: 0 kB > ShmemPmdMapped: 0 kB > LazyFreePages: 1046528 kB > > After: > MemAvailable: 44415124 kB > ... > AnonHugePages: 6144 kB > ShmemHugePages: 0 kB > ShmemPmdMapped: 0 kB > LazyFreePages: 1046528 kB > > MADV_FREE pages are not accounted for NR_LAZYFREE since they have been > put on inactive file LRU and accounted into available memory. > Accounting here would double account them. > > Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> > --- > mm/page_alloc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index cab50e8..58ceca5 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5005,6 +5005,7 @@ long si_mem_available(void) > unsigned long wmark_low = 0; > unsigned long pages[NR_LRU_LISTS]; > unsigned long reclaimable; > + unsigned long lazyfree; > struct zone *zone; > int lru; > > @@ -5038,6 +5039,10 @@ long si_mem_available(void) > global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE); > available += reclaimable - min(reclaimable / 2, wmark_low); > > + /* Lazyfree pages are reclaimable when memory pressure is hit */ > + lazyfree = global_node_page_state(NR_LAZYFREE); > + available += lazyfree - min(lazyfree / 2, wmark_low); > + > if (available < 0) > available = 0; > return available;
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