From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH 12/12] mm: per BDI congestion feedback From: Peter Zijlstra In-Reply-To: <20070405162425.eb78c701.akpm@linux-foundation.org> References: <20070405174209.498059336@programming.kicks-ass.net> <20070405174320.649550491@programming.kicks-ass.net> <20070405162425.eb78c701.akpm@linux-foundation.org> Content-Type: text/plain Date: Fri, 06 Apr 2007 09:01:57 +0200 Message-Id: <1175842917.6483.130.camel@twins> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com, nikita@clusterfs.com List-ID: On Thu, 2007-04-05 at 16:24 -0700, Andrew Morton wrote: > On Thu, 05 Apr 2007 19:42:21 +0200 > root@programming.kicks-ass.net wrote: > > > Now that we have per BDI dirty throttling is makes sense to also have oer BDI > > congestion feedback; why wait on another device if the current one is not > > congested. > > Similar comments apply. congestion_wait() should be called > throttle_at_a_rate_proportional_to_the_speed_of_presently_uncongested_queues(). > > If a process is throttled in the page allocator waiting for pages to become > reclaimable, that process absolutely does not care whether those pages were > previously dirty against /dev/sda or against /dev/sdb. It wants to be woken > up for writeout completion against any queue. OK, so you disagree with Miklos' 2nd point here: http://lkml.org/lkml/2007/4/4/137 And in the light of clear_bdi_congestion() being called for each writeout completion under the threshold this does make sense. So this whole 8-12/12 series is not needed and just served as an learning experience :-/ -- 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