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bh=UghZOtEbbNtkuyHw6OG+q34Eguh17rpI6TW2xy+k26s=; b=Fsjsh2O/oToKVq/H89joyhrl1vB+8BTBfApNgEKpxECOhMpD8okC2XulgoKvPMmysJjbXj bGEzv3xuk/Jor7Bg== Received: from suse.de (unknown [10.163.43.106]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id C064A2C142; Wed, 31 Aug 2022 10:02:50 +0000 (UTC) Date: Wed, 31 Aug 2022 11:02:49 +0100 From: Mel Gorman To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, ldufour@linux.ibm.com, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, changbin.du@intel.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, arnd@arndb.de, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-mm@kvack.org, iommu@lists.linux.dev, kasan-dev@googlegroups.com, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 03/30] Lazy percpu counters Message-ID: <20220831100249.f2o27ri7ho4ma3pe@suse.de> References: <20220830214919.53220-1-surenb@google.com> <20220830214919.53220-4-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20220830214919.53220-4-surenb@google.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661940180; a=rsa-sha256; cv=none; b=QYkewzE9qWJLMsHRF5lCkzZyhGHw2IcwrsE+8/TYg86Qf4oMo91mEhB4XKKf//uIIdw3vJ su160rhTdxcGl3i7ha7krJeBDp9DwTMugZSbZ1iNPp6cqh4FF45KhkES979uuyx4RYUhnr 3OkvtaB+nKfBR8+Hxk1CWS7Xpm8m4G4= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=PRBKEeRr; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b="Fsjsh2O/"; spf=pass (imf06.hostedemail.com: domain of mgorman@suse.de designates 195.135.220.28 as permitted sender) smtp.mailfrom=mgorman@suse.de; dmarc=pass (policy=none) header.from=suse.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661940180; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=UghZOtEbbNtkuyHw6OG+q34Eguh17rpI6TW2xy+k26s=; b=ApEFQZbVPpx3yXGbkQ0nek66OiTkPb9jcQKQ0o3C6QbFWLuoGC882LA8+F+WB9Y+TT0NQu n2yORC5ZGIADZYXM8tR/PV4fo+dskL74qaOcVyX/QLJNL3e2MjG/fRe1iDcKuqZbSZqpfi +7bXnszvDd8MENVTA1n/ansjkQxcXlY= X-Stat-Signature: 964imji1xnp5p876s7cwg16webjtcrpz X-Rspamd-Queue-Id: D708218003F X-Rspamd-Server: rspam04 X-Rspam-User: Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=PRBKEeRr; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b="Fsjsh2O/"; spf=pass (imf06.hostedemail.com: domain of mgorman@suse.de designates 195.135.220.28 as permitted sender) smtp.mailfrom=mgorman@suse.de; dmarc=pass (policy=none) header.from=suse.de X-HE-Tag: 1661940179-422709 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 30, 2022 at 02:48:52PM -0700, Suren Baghdasaryan wrote: > From: Kent Overstreet > > 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 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