From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6484ECAAD5 for ; Wed, 31 Aug 2022 10:03:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230246AbiHaKDB (ORCPT ); Wed, 31 Aug 2022 06:03:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56530 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229913AbiHaKDA (ORCPT ); Wed, 31 Aug 2022 06:03:00 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15824BD1FF; Wed, 31 Aug 2022 03:03:00 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 60E182226F; Wed, 31 Aug 2022 10:02:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1661940178; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=UghZOtEbbNtkuyHw6OG+q34Eguh17rpI6TW2xy+k26s=; b=PRBKEeRroKw9uKicRWHW+510+yPrLqUkpbnRk+7WMXhWuFKJOM0BT+MpyEO2iwAv8hytIA btsLNyDayNr7GOZofmiVg24uPISDfKOix86GB2r26KRZAxV3CAmeg/EZgjlKPFALHLF+rj W6qDhGUMZIbq1FBe7+V0SXRtsy5jHbc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1661940178; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; 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> Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org 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