From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from max.fys.ruu.nl (max.fys.ruu.nl [131.211.32.73]) by kvack.org (8.8.7/8.8.7) with ESMTP id MAA11621 for ; Tue, 9 Dec 1997 12:55:51 -0500 Date: Tue, 9 Dec 1997 18:43:13 +0100 (MET) From: Rik van Riel Reply-To: H.H.vanRiel@fys.ruu.nl Subject: vhand design flaw :((, new patch instead Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: linux-mm Cc: linux-kernel List-ID: Hi, I found (much to my dissapointment) a fundamental design flaw in my vhand patch that explains very well the different results people have had with my patch. It doesn't affect stability, just performance, so when vhand works for you, there's no reason not to use it anymore, except for the fact that something better's around... The new patch consists of two parts: - the anti-fragmentation patch from Zlatko Calusic (really useful) - kswapd now also ages mmap'ed pages. for this part I have just copied some code from vmscan.c into mmap.c, so it should all be rock-solid... The results of this patch are: - kswapd is more careful about kicking out mmap'ed pages and buffers and as a result of this: - kswapd takes more CPU time to swap out a page - kswapd has to swap out less pages - there are (far) less pagefaults - now there's no vhand daemon that constantly uses CPU I hope that the total CPU usage of kswapd hasn't increased much, if it has increased at all. I for one know that system performance was boosted quite a bit (more than with the vhand patch). If this runs for a lot of people, I'll even send it to Linus (there's no new code in it, so we can consider this a bug-fix) grtz, Rik. ps: making it a config option is also possible... We could even consider adding another (simpler) aging algorithm to kswapd for (huge) systems that have more I/O bandwith to spare than they have CPU time. -- Send Linux memory-management wishes to me: I'm currently looking for something to hack...