Messages in this thread | | | From | Eric Dumazet <> | Date | Tue, 8 Mar 2022 15:49:48 -0800 | Subject | Re: [PATCH v2] mm/page_alloc: call check_new_pages() while zone spinlock is not held |
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On Mon, Mar 7, 2022 at 1:15 AM Mel Gorman <mgorman@techsingularity.net> wrote: > > On Fri, Mar 04, 2022 at 09:02:15AM -0800, Eric Dumazet wrote: > > From: Eric Dumazet <edumazet@google.com> > > > > For high order pages not using pcp, rmqueue() is currently calling > > the costly check_new_pages() while zone spinlock is held, > > and hard irqs masked. > > > > This is not needed, we can release the spinlock sooner to reduce > > zone spinlock contention. > > > > Note that after this patch, we call __mod_zone_freepage_state() > > before deciding to leak the page because it is in bad state. > > > > v2: We need to keep interrupts disabled to call __mod_zone_freepage_state() > > > > Signed-off-by: Eric Dumazet <edumazet@google.com> > > Cc: Mel Gorman <mgorman@techsingularity.net> > > Cc: Vlastimil Babka <vbabka@suse.cz> > > Cc: Michal Hocko <mhocko@kernel.org> > > Cc: Shakeel Butt <shakeelb@google.com> > > Cc: Wei Xu <weixugc@google.com> > > Cc: Greg Thelen <gthelen@google.com> > > Cc: Hugh Dickins <hughd@google.com> > > Cc: David Rientjes <rientjes@google.com> > > Ok, this is only more expensive in the event pages on the free list have > been corrupted whch is already very unlikely so thanks! > > Acked-by: Mel Gorman <mgorman@techsingularity.net> >
One remaining question is:
After your patch ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists"), do we want to change check_pcp_refill()/check_new_pcp() to check all pages, and not only the head ?
Or was it a conscious choice of yours ? (I presume part of the performance gains came from not having to bring ~7 cache lines per 32KB chunk on x86)
Thanks !
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