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From: Eric Dumazet <edumazet@google.com>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>, Vlastimil Babka <vbabka@suse.cz>,
	Michal Hocko <mhocko@kernel.org>,
	Shakeel Butt <shakeelb@google.com>, Wei Xu <weixugc@google.com>,
	Greg Thelen <gthelen@google.com>, Hugh Dickins <hughd@google.com>,
	David Rientjes <rientjes@google.com>
Subject: Re: [PATCH v2] mm/page_alloc: call check_new_pages() while zone spinlock is not held
Date: Tue, 8 Mar 2022 15:49:48 -0800	[thread overview]
Message-ID: <CANn89iLmwT4XQ6JPi4C7dO+Q2O_j7HK19-TAo4nA1NUf8ZSLBw@mail.gmail.com> (raw)
In-Reply-To: <20220307091541.GD15701@techsingularity.net>

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 !

  reply	other threads:[~2022-03-09  1:07 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-04 17:02 [PATCH v2] mm/page_alloc: call check_new_pages() while zone spinlock is not held Eric Dumazet
2022-03-04 19:19 ` Shakeel Butt
2022-03-06 22:15 ` David Rientjes
2022-03-07  9:15 ` Mel Gorman
2022-03-08 23:49   ` Eric Dumazet [this message]
2022-03-09 12:32     ` Mel Gorman
2022-03-09 17:32       ` Eric Dumazet
2022-03-12 15:43       ` [mm/page_alloc] 8212a964ee: vm-scalability.throughput 30.5% improvement kernel test robot
2022-03-12 18:58         ` Vlastimil Babka
2022-03-12 23:26           ` Eric Dumazet
2022-03-13  9:28             ` Vlastimil Babka
2022-03-13 21:10               ` Eric Dumazet
2022-03-13 21:18                 ` Matthew Wilcox
2022-03-13 21:27                   ` Eric Dumazet
2022-03-13 21:36                     ` Eric Dumazet
2022-03-14  9:09                 ` Vlastimil Babka
2022-03-07  9:24 ` [PATCH v2] mm/page_alloc: call check_new_pages() while zone spinlock is not held Vlastimil Babka

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