From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx172.postini.com [74.125.245.172]) by kanga.kvack.org (Postfix) with SMTP id 4CF296B0071 for ; Fri, 8 Jun 2012 04:08:46 -0400 (EDT) Received: by dakp5 with SMTP id p5so2493171dak.14 for ; Fri, 08 Jun 2012 01:08:45 -0700 (PDT) Date: Fri, 8 Jun 2012 01:07:05 -0700 From: Anton Vorontsov 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: Sender: owner-linux-mm@kvack.org List-ID: 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 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, 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