From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from haymarket.ed.ac.uk (haymarket.ed.ac.uk [129.215.128.53]) by kvack.org (8.8.7/8.8.7) with ESMTP id HAA24415 for ; Mon, 6 Jul 1998 07:08:06 -0400 Date: Mon, 6 Jul 1998 11:31:12 +0100 Message-Id: <199807061031.LAA00800@dax.dcs.ed.ac.uk> From: "Stephen C. Tweedie" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: Re: cp file /dev/zero <-> cache [was Re: increasing page size] In-Reply-To: References: Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: Rik van Riel , Linux MM , Linux Kernel , Stephen Tweedie List-ID: Hi, On Sun, 5 Jul 1998 20:38:57 +0200 (CEST), Andrea Arcangeli said: > kswapd must swap _nothing_ if _freeable_ cache memory is allocated. > kswapd _must_ consider freeable cache memory as _free_ not used memory > and so it must not start swapping out useful code and data for make > space for allocating more cache. You just can't make blanket statements like that! If you're on an 8MB or 16MB box doing compilations, then you desperately want unused process data pages --- idle bits of inetd, lpd, sendmail, init, the shell, the top-level make and so on --- to be swapped out to make room for a few more header files in cache. Throwing away all cache pages will also destroy readahead and prevent you from caching pages of a binary between successive invocations. That's the problem with all rules of the form "memory management MUST prioritise X over Y". There are always cases where it is not true. What we need is a balance, not arbitrary rules like that. --Stephen -- This is a majordomo managed list. To unsubscribe, send a message with the body 'unsubscribe linux-mm me@address' to: majordomo@kvack.org