From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sun, 26 Jun 2005 18:34:14 -0400 (EDT) From: Rik Van Riel Subject: [PATCH] 0/2 swap token tuning Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Song Jiang List-ID: A while ago the swap token (aka token based thrashing control) mechanism was introduced into Linux. This code improves performance under heavy VM loads, but can reduce performance under very light VM loads. The cause turns out to be me overlooking something in the original token based thrashing control paper: the swap token is only supposed to be enforced while the task holding the swap token is paging data in, not while the task is running (and referencing its working set). The temporary solution in Linux was to disable the swap token code and have users turn it on again via /proc. The following patch instead approximates the "only enforce the swap token if the task holding it is swapping something in" idea. This should make sure the swap token is effectively disabled when the VM load is low. I have not benchmarked these patches yet; instead, I'm posting them before the weekend is over, hoping to catch a bit of test time from others while my own tests are being run ;) -- The Theory of Escalating Commitment: "The cost of continuing mistakes is borne by others, while the cost of admitting mistakes is borne by yourself." -- Joseph Stiglitz, Nobel Laureate in Economics -- 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: aart@kvack.org