From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailhost.uni-koblenz.de (mailhost.uni-koblenz.de [141.26.64.1]) by kvack.org (8.8.7/8.8.7) with ESMTP id TAA29880 for ; Sat, 29 May 1999 19:40:39 -0400 Received: from lappi.waldorf-gmbh.de (cacc-23.uni-koblenz.de [141.26.131.23]) by mailhost.uni-koblenz.de (8.9.1/8.9.1) with ESMTP id BAA20756 for ; Sun, 30 May 1999 01:40:25 +0200 (MET DST) Date: Sat, 29 May 1999 17:07:12 +0200 From: Ralf Baechle Subject: Re: Q: PAGE_CACHE_SIZE? Message-ID: <19990529170712.D1517@uni-koblenz.de> References: <14159.137.169623.500547@dukat.scot.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <14159.137.169623.500547@dukat.scot.redhat.com>; from Stephen C. Tweedie on Fri, May 28, 1999 at 09:46:01PM +0100 Sender: owner-linux-mm@kvack.org To: "Stephen C. Tweedie" Cc: Alan Cox , Rik van Riel , ak@muc.de, ebiederm+eric@ccr.net, linux-kernel@vger.rutgers.edu, linux-mm@kvack.org List-ID: On Fri, May 28, 1999 at 09:46:01PM +0100, Stephen C. Tweedie wrote: > If we did in fact use the 4k minipage for all kernel get_free_page() > allocations as usual, but used the larger 32k buddy heap pages for all > VM allocations, then 8K kernel allocations (eg. stack allocations and > large NFS packets) become trivial to deal with. > > The biggest problem we have had with these multi-page allocations up to > now is fragmentation in the VM. If we populate the _entire_ VM in > multiples of 8k or more then we can never see such fragmentation at all. > 8k might actually be a reasonable pagesize even on low memory machines: > we found in 2.2 that the increased size of the kernel was compensated > for by more efficient swapping so that things still went faster in low > memory than under 2.2, and large pages may well have the same tradeoff. I'm working on Linux/MIPS64 and I intend to cleanup the code such that the kernel can be built for different page sizes. I intend to benchmark things for curiosity. Maybe it's some viable system tuning option, even though a compile time one. Ralf -- To unsubscribe, send a message with 'unsubscribe linux-mm my@address' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/