From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 207066B004D for ; Wed, 15 Jul 2009 23:51:39 -0400 (EDT) Date: Wed, 15 Jul 2009 20:51:09 -0700 From: Andrew Morton Subject: Re: [PATCH -mm] throttle direct reclaim when too many pages are isolated already Message-Id: <20090715205109.5f86e416.akpm@linux-foundation.org> In-Reply-To: <4A5EA1A4.1080502@redhat.com> References: <20090715223854.7548740a@bree.surriel.com> <20090715194820.237a4d77.akpm@linux-foundation.org> <4A5E9A33.3030704@redhat.com> <20090715202114.789d36f7.akpm@linux-foundation.org> <4A5E9E4E.5000308@redhat.com> <20090715203854.336de2d5.akpm@linux-foundation.org> <4A5EA1A4.1080502@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: KOSAKI Motohiro , LKML , linux-mm , Wu Fengguang List-ID: On Wed, 15 Jul 2009 23:42:28 -0400 Rik van Riel wrote: > Andrew Morton wrote: > > On Wed, 15 Jul 2009 23:28:14 -0400 Rik van Riel wrote: > > >> If we are stuck at this point in the page reclaim code, > >> it is because too many other tasks are reclaiming pages. > >> > >> That makes it fairly safe to just return SWAP_CLUSTER_MAX > >> here and hope that __alloc_pages() can get a page. > >> > >> After all, if __alloc_pages() thinks it made progress, > >> but still cannot make the allocation, it will call the > >> pageout code again. > > > > Which will immediately return because the caller still has > > fatal_signal_pending()? > > Other processes are in the middle of freeing pages at > this point, so we should succeed in __alloc_pages() > fairly quickly (and then die and free all our memory). What if it's a uniprocessor machine and all those processes are scheduled out? We sit there chewing 100% CPU and not doing anything afaict. Even if it _is_ SMP, we could still chew decent-sized blips of CPU time rattling around waiting for something to happen. -- 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