From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f45.google.com (mail-wg0-f45.google.com [74.125.82.45]) by kanga.kvack.org (Postfix) with ESMTP id BE0376B0085 for ; Tue, 14 Oct 2014 12:34:02 -0400 (EDT) Received: by mail-wg0-f45.google.com with SMTP id m15so11543201wgh.16 for ; Tue, 14 Oct 2014 09:34:02 -0700 (PDT) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id bj4si16943675wib.23.2014.10.14.09.34.01 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 Oct 2014 09:34:01 -0700 (PDT) Date: Tue, 14 Oct 2014 12:33:54 -0400 From: Johannes Weiner Subject: Re: [patch 1/3] mm: memcontrol: lockless page counters Message-ID: <20141014163354.GA23911@phnom.home.cmpxchg.org> References: <1413251163-8517-1-git-send-email-hannes@cmpxchg.org> <1413251163-8517-2-git-send-email-hannes@cmpxchg.org> <20141014155647.GA6414@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141014155647.GA6414@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , Vladimir Davydov , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tue, Oct 14, 2014 at 05:56:47PM +0200, Michal Hocko wrote: > On Mon 13-10-14 21:46:01, Johannes Weiner wrote: > > Memory is internally accounted in bytes, using spinlock-protected > > 64-bit counters, even though the smallest accounting delta is a page. > > The counter interface is also convoluted and does too many things. > > > > Introduce a new lockless word-sized page counter API, then change all > > memory accounting over to it. The translation from and to bytes then > > only happens when interfacing with userspace. > > > > The removed locking overhead is noticable when scaling beyond the > > per-cpu charge caches - on a 4-socket machine with 144-threads, the > > following test shows the performance differences of 288 memcgs > > concurrently running a page fault benchmark: > > I assume you had root.use_hierarchy = 1, right? Processes wouldn't bounce > on the same lock otherwise. Yep. That's already the default on most distros, and will be in the kernel in unified hierarchy. > > Signed-off-by: Johannes Weiner > > You have only missed MAINTAINERS... Hm, we can add it, but then again scripts/get_maintainer.pl should already do the right thing. I find myself using it with --git all the time to find the people that actually worked on the code recently, not just the ones listed in there - which might be stale information. > Acked-by: Michal Hocko Thank you, Michal! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org