From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx135.postini.com [74.125.245.135]) by kanga.kvack.org (Postfix) with SMTP id AE86B6B0092 for ; Fri, 18 May 2012 10:25:00 -0400 (EDT) Date: Fri, 18 May 2012 16:24:43 +0200 From: Jan Kara Subject: Re: [PATCH 2/2] block: Convert BDI proportion calculations to flexible proportions Message-ID: <20120518142443.GA6875@quack.suse.cz> References: <1337096583-6049-1-git-send-email-jack@suse.cz> <1337096583-6049-3-git-send-email-jack@suse.cz> <1337292273.4281.101.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1337292273.4281.101.camel@twins> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Jan Kara , Wu Fengguang , LKML , linux-mm@kvack.org On Fri 18-05-12 00:04:33, Peter Zijlstra wrote: > On Tue, 2012-05-15 at 17:43 +0200, Jan Kara wrote: > > +static struct timer_list writeout_period_timer = > > + TIMER_DEFERRED_INITIALIZER(writeout_period, 0, 0); > > So the problem with using a deferred timer is that it 'ignores' idle > time. So if a very busy period is followed by a real quiet period you'd > expect all the proportions to have aged to 0, but they won't have. Ah, I see. Thanks for warning me. > One way to solve that is to track a jiffies count of the last time the > timer triggered and compute the missed periods from that and extend > fprop_new_period() to deal with period increments of more than 1. Yeah, that should be easy enough so I'll try it that way since I presume it's nicer to power usage to use deferred timers if it's reasonably possible. Honza -- Jan Kara SUSE Labs, CR -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org