From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id 11BEB6B0032 for ; Mon, 30 Mar 2015 10:00:04 -0400 (EDT) Received: by pactp5 with SMTP id tp5so1725488pac.1 for ; Mon, 30 Mar 2015 07:00:03 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2001:1868:205::9]) by mx.google.com with ESMTPS id w1si14934793pdh.80.2015.03.30.07.00.02 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 30 Mar 2015 07:00:02 -0700 (PDT) Date: Mon, 30 Mar 2015 15:59:48 +0200 From: Peter Zijlstra Subject: Re: [RFC] vmstat: Avoid waking up idle-cpu to service shepherd work Message-ID: <20150330135948.GY23123@twins.programming.kicks-ass.net> References: <20150327091613.GE27490@worktop.programming.kicks-ass.net> <20150327093023.GA32047@worktop.ger.corp.intel.com> <20150328095322.GH27490@worktop.programming.kicks-ass.net> <55169723.3070006@linaro.org> <20150328134457.GK27490@worktop.programming.kicks-ass.net> <20150329102440.GC32047@worktop.ger.corp.intel.com> <20150330124746.GI21418@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Viresh Kumar Cc: Andrew Morton , Johannes Weiner , Christoph Lameter , Linaro Kernel Mailman List , Linux Kernel Mailing List , vinmenon@codeaurora.org, shashim@codeaurora.org, Michal Hocko , Mel Gorman , dave@stgolabs.net, Konstantin Khlebnikov , Linux Memory Management List , Suresh Siddha , Thomas Gleixner On Mon, Mar 30, 2015 at 06:44:22PM +0530, Viresh Kumar wrote: > On 30 March 2015 at 18:17, Peter Zijlstra wrote: > > No, I means something else with that. We can remove the > > tvec_base::running_timer field. Everything that uses that can use > > tbase_running() AFAICT. > > Okay, there is one instance which still needs it. > > migrate_timers(): > > BUG_ON(old_base->running_timer); > > What I wasn't sure about it is if we get can drop this statement or not. > If we decide not to drop it, then we can convert running_timer into a bool. Yeah, so that _should_ not trigger (obviously), and while I agree with the sentiment of sanity checks, I'm not sure its worth keeping that variable around just for that. Anyway, while I'm looking at struct tvec_base I notice the cpu member should be second after the lock, that'll save 8 bytes on the structure on 64bit machines. -- 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