From mboxrd@z Thu Jan 1 00:00:00 1970 From: kanoj@google.engr.sgi.com (Kanoj Sarcar) Message-Id: <200003270800.AAA65612@google.engr.sgi.com> Subject: Re: [PATCH] Re: kswapd Date: Mon, 27 Mar 2000 00:00:21 -0800 (PST) In-Reply-To: from "Linus Torvalds" at Mar 26, 2000 10:07:48 PM MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: riel@nl.linux.org, Russell King , linux-mm@kvack.org, linux-kernel@vger.rutgers.edu List-ID: > > On the other hand you're definitely right that this is not a new bug > introduced by you, Kanoj - this seems to be just a thinko that has been Whew, as long as I can keep that beer I was going to send to Russell on Rik's suggestion for myself! :-) On a more serious note, I know too little about the application load that Rik/Russell is talking about to understand what's going on, but I have the vague suspicion that Rik's patch is just a part fix to the problem, and that maybe we might be doing too many kswapd wakes ups via the balancing code. This is my reasoning: Rik's patch makes it so that before kswapd undertakes heavy weight work, it yields the cpu ... then it checks whether it has to do the work (via zone_wake_kswapd). This is the only difference over pre3. If this is improving things a lot, that makes me believe that the memory-low condition is subsiding (pages are being freed up) just after kswapd has yielded, and before it gets scheduled onto the cpu again. This depends on the app and its priority too, I guess. If there is an app load where the pages are not freed, Rik's patch would _probably_ not be able to help. Its better than nothing, but if you wanted to do the best you could, you need to add more yield points into the body of kswapd code (which I suspect will not be free of side effects possibly). The other part about possibly doing too many kswapd wakeups is just a hunch, not directly related to this patch. I will forward a balancing patch on the mailing lists next for people to try. Kanoj -- 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.eu.org/Linux-MM/