From: Matthew Wilcox <willy@infradead.org>
To: Breno Leitao <leitao@debian.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org, kas@kernel.org,
shakeel.butt@linux.dev, usama.arif@linux.dev,
kernel-team@meta.com
Subject: Re: [PATCH] mm/vmstat: spread vmstat_update requeue across the stat interval
Date: Thu, 2 Apr 2026 13:49:34 +0100 [thread overview]
Message-ID: <ac5l3myFf_dxtRji@casper.infradead.org> (raw)
In-Reply-To: <20260401-vmstat-v1-1-b68ce4a35055@debian.org>
On Wed, Apr 01, 2026 at 06:57:50AM -0700, Breno Leitao wrote:
> vmstat_update uses round_jiffies_relative() when re-queuing itself,
> which aligns all CPUs' timers to the same second boundary. When many
> CPUs have pending PCP pages to drain, they all call decay_pcp_high() ->
> free_pcppages_bulk() simultaneously, serializing on zone->lock and
> hitting contention.
>
> Introduce vmstat_spread_delay() which distributes each CPU's
> vmstat_update evenly across the stat interval instead of aligning them.
But, uh, round_jiffies_relative() is _supposed_ to do that! Look at
both the documentation and implementation. Why isn't it working?
next prev parent reply other threads:[~2026-04-02 12:49 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-01 13:57 [PATCH] mm/vmstat: spread vmstat_update requeue across the stat interval Breno Leitao
2026-04-01 14:25 ` Johannes Weiner
2026-04-01 14:39 ` Breno Leitao
2026-04-01 14:57 ` Johannes Weiner
2026-04-01 14:47 ` Breno Leitao
2026-04-01 15:01 ` Kiryl Shutsemau
2026-04-01 15:23 ` Usama Arif
2026-04-01 15:43 ` Breno Leitao
2026-04-01 15:50 ` Usama Arif
2026-04-01 15:52 ` Breno Leitao
2026-04-01 17:46 ` Vlastimil Babka (SUSE)
2026-04-02 12:40 ` Vlastimil Babka (SUSE)
2026-04-02 13:33 ` Breno Leitao
2026-04-02 12:43 ` Dmitry Ilvokhin
2026-04-02 7:18 ` Michal Hocko
2026-04-02 12:49 ` Matthew Wilcox [this message]
2026-04-02 13:26 ` Breno Leitao
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