From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 45FA1900194 for ; Thu, 23 Jun 2011 09:39:09 -0400 (EDT) Date: Thu, 23 Jun 2011 15:39:04 +0200 From: Andrea Righi Subject: Re: [PATCH v2] fadvise: move active pages to inactive list with POSIX_FADV_DONTNEED Message-ID: <20110623133904.GA1479@thinkpad> References: <1308810981-5286-1-git-send-email-andrea@betterlinux.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Theodore Tso Cc: Andrew Morton , Minchan Kim , Rik van Riel , Peter Zijlstra , Johannes Weiner , KAMEZAWA Hiroyuki , Andrea Arcangeli , Hugh Dickins , Jerry James , Marcus Sorensen , Matt Heaton , KOSAKI Motohiro , linux-mm , LKML On Thu, Jun 23, 2011 at 08:10:47AM -0400, Theodore Tso wrote: > > On Jun 23, 2011, at 2:36 AM, Andrea Righi wrote: > > > > > With the following solution when posix_fadvise(POSIX_FADV_DONTNEED) is > > called for an active page instead of removing it from the page cache it > > is added to the tail of the inactive list. Otherwise, if it's already in > > the inactive list the page is removed from the page cache. > > > Have you thought about this heuristic? If the page is active, try to > remove it from the current process's page table. If that drops the > use count of the page to zero, then drop it from the page cache; > otherwise, leave it alone. > > That way, if the page is being used by anyone else, we don't touch > the page at all. fadvise() should only affect the current process; if > it's available to non-root users, it shouldn't be affecting other > processes, and if it is being actively used by some other process, > removing it from their page tables so it can be put on the inactive > list counts as interference, doesn't it? If the page is mapped in other process page tables we don't touch the page at all (see lru_deactivate_fn in mm/swap.c). So the heuristic above it's already implemented. I should have said this explicitly in my description... -Andrea -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org