From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <45C15CAB.2090607@redhat.com> Date: Wed, 31 Jan 2007 22:21:15 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [patch] not to disturb page LRU state when unmapping memory range References: <1170279811.10924.32.camel@lappy> <20070131140450.09f174e9.akpm@osdl.org> <1170282300.10924.50.camel@lappy> <20070131144855.8fe255ff.akpm@osdl.org> In-Reply-To: <20070131144855.8fe255ff.akpm@osdl.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Peter Zijlstra , Hugh Dickins , Ken Chen , linux-mm@kvack.org List-ID: Andrew Morton wrote: > Perhaps we're approaching this from the wrong direction. Rather than > looking at the code and saying "hey, we should change that", we should be > looking at workloads and seeing how they can be improved. Perhaps. I think this makes a lot of sense. It may not be benchmarkable, because there is no exhaustive test of workloads, but we can at least come up with several conceptual groups of workloads that should be kept in mind when changing things to the VM. I could think of a few workloads and their characteristics and desired behaviour: 1) desktop workload - program working sets need to be kept in memory and protected from pressure by streaming IO 2) database workload - some pages get accessed more frequently than others, those need to be kept resident in memory 3) file server workload - some pages get accessed more frequently than others, those need to be kept resident in memory. This is similar to the database workload, except the inter-reference distance on a file server is WAY larger and an LRU queue is likely not large enough to catch even the frequently accessed pages. 4) web server workload - somewhere in-between the desktop and the file server, the working sets of the server programs need to be kept in memory, and we want to cache the frequently accessed data pages 5) developer desktop - like the desktop workload, except we have programs like git and rsync doing streaming IO with double accesses next to each other, which will push the working sets of the desktop programs out of memory if our use-once algorithm gets fooled 6) realtime data processing - this kind of workload is usually mlocked, but sometimes still wants to do lots of file IO. We need to make sure the VM does not get upset by the sometimes large amount of mlocked data 7) ... fill in your own workload here :) -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. -- 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