Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932503Ab2FHIIw (ORCPT ); Fri, 8 Jun 2012 04:08:52 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:49594 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760311Ab2FHIIq (ORCPT ); Fri, 8 Jun 2012 04:08:46 -0400 Date: Fri, 8 Jun 2012 01:07:05 -0700 From: Anton Vorontsov To: Pekka Enberg Cc: KOSAKI Motohiro , Leonid Moiseichuk , Bartlomiej Zolnierkiewicz , John Stultz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linaro-kernel@lists.linaro.org, patches@linaro.org, kernel-team@android.com Subject: Re: [PATCH 2/5] vmevent: Convert from deferred timer to deferred work Message-ID: <20120608080704.GB6362@lizard> References: <20120601122118.GA6128@lizard> <1338553446-22292-2-git-send-email-anton.vorontsov@linaro.org> <4FD170AA.10705@gmail.com> <20120608065828.GA1515@lizard> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1578 Lines: 40 On Fri, Jun 08, 2012 at 10:03:24AM +0300, Pekka Enberg wrote: > On Fri, Jun 8, 2012 at 9:58 AM, Anton Vorontsov > wrote: > > If you're saying that we should set up a timer in the userland and > > constantly read /proc/vmstat, then we will cause CPU wake up > > every 100ms, which is not acceptable. Well, we can try to introduce > > deferrable timers for the userspace. But then it would still add > > a lot more overhead for our task, as this solution adds other two > > context switches to read and parse /proc/vmstat. I guess this is > > not a show-stopper though, so we can discuss this. > > > > Leonid, Pekka, what do you think about the idea? > > That's exactly the kind of half-assed ABI that lead to people > inventing out-of-tree lowmem notifiers in the first place. :-) Well, at least powersaving-wise, the solution w/ userland deferred timers would be much better then just looping over /proc/vmstat each 100ms, and it is comparable to vmevent. Not pretty, but still would work. > I'd be more interested to know what people think of Minchan's that > gets rid of vmstat sampling. I answered to Minchan's post. The thing is that Minchan's idea is not a substitution for vmevent. To me it seems like a shrinker w/ some pre-filter. Thanks, -- Anton Vorontsov Email: cbouatmailru@gmail.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/