linux-kernel - Re: [RFC PATCH 03/30] Lazy percpu counters

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Message-ID: <20220831100249.f2o27ri7ho4ma3pe@suse.de>
Date:   Wed, 31 Aug 2022 11:02:49 +0100
From:   Mel Gorman <mgorman@...e.de>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     akpm@...ux-foundation.org, kent.overstreet@...ux.dev,
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Subject: Re: [RFC PATCH 03/30] Lazy percpu counters

On Tue, Aug 30, 2022 at 02:48:52PM -0700, Suren Baghdasaryan wrote:
> From: Kent Overstreet <kent.overstreet@...ux.dev>
> 
> This patch adds lib/lazy-percpu-counter.c, which implements counters
> that start out as atomics, but lazily switch to percpu mode if the
> update rate crosses some threshold (arbitrarily set at 256 per second).
> 
> Signed-off-by: Kent Overstreet <kent.overstreet@...ux.dev>

Why not use percpu_counter? It has a per-cpu counter that is synchronised
when a batch threshold (default 32) is exceeded and can explicitly sync
the counters when required assuming the synchronised count is only needed
when reading debugfs.

-- 
Mel Gorman
SUSE Labs