From mboxrd@z Thu Jan 1 00:00:00 1970 From: KOSAKI Motohiro Subject: Re: [PATCH] mm: disallow direct reclaim page writeback Date: Thu, 15 Apr 2010 13:09:01 +0900 (JST) Message-ID: <20100415130212.D16E.A69D9226@jp.fujitsu.com> References: <20100414085132.GJ25756@csn.ul.ie> <20100415013436.GO2493@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Cc: kosaki.motohiro@jp.fujitsu.com, Mel Gorman , Chris Mason , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org To: Dave Chinner Return-path: In-Reply-To: <20100415013436.GO2493@dastard> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org Hi > How about this? For now, we stop direct reclaim from doing writeback > only on order zero allocations, but allow it for higher order > allocations. That will prevent the majority of situations where > direct reclaim blows the stack and interferes with background > writeout, but won't cause lumpy reclaim to change behaviour. > This reduces the scope of impact and hence testing and validation > the needs to be done. Tend to agree. but I would proposed slightly different algorithm for avoind incorrect oom. for high order allocation allow to use lumpy reclaim and pageout() for both kswapd and direct recl= aim for low order allocation - kswapd: always delegate io to flusher thread - direct reclaim: delegate io to flusher thread only if vm pressure is = low This seems more safely. I mean Who want see incorrect oom regression? I've made some pathes for this. I'll post it as another mail. > Then we can work towards allowing lumpy reclaim to use background > threads as Chris suggested for doing specific writeback operations > to solve the remaining problems being seen. Does this seem like a > reasonable compromise and approach to dealing with the problem? Tend to agree. probably now we are discussing right approach. but this is definitely needed deep thinking. then, I can't take exactly answer yet. -- 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