From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 8 Nov 2007 16:53:20 +0000 Subject: Re: bug #5493 Message-ID: <20071108165320.GA23882@skynet.ie> References: <32209efe0711071800v4bc0c62er7bc462f1891c9dcd@mail.gmail.com> <20071107191247.04d74241.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20071107191247.04d74241.akpm@linux-foundation.org> From: mel@skynet.ie (Mel Gorman) Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Natalie Protasevich , linux-mm@kvack.org, riel@redhat.com List-ID: On (07/11/07 19:12), Andrew Morton didst pronounce: > (added linux-mm) > > > On Wed, 7 Nov 2007 18:00:20 -0800 "Natalie Protasevich" wrote: > > Andrew, this one http://bugzilla.kernel.org/show_bug.cgi?id=5493 looks > > serious, and I'm not sure who to ping now that the reporter can't test > > it anymore. > > This is about mprotect ... > > No, I don't think anyone knows how to fix that. > > Fortunately I'm only aware of the one person hitting this problem. > I tried out the test program with 1GiB of memory. First, the program could not even run unless mprotect was called again to make pages read-only a second time - otherwise mprotect would report ENOMEM because VMAs were not getting merged. That in itself was a little unexpected. After fixing that, I ran with varying number of pages and got the following timings 300000: 68.36 seconds 295000: 55.07 seconds 290000: 41.79 seconds 285000: 31.71 seconds 280000: 22.92 seconds 275000: 11.27 seconds 270000: 5.60 seconds 265000: 5.94 seconds 260000: 5.77 seconds 255000: 5.65 seconds 250000: 5.53 seconds 245000: 5.42 seconds 240000: 5.31 seconds The system has about 250000 pages and around that mark it seemed fine in terms of time-to-completion. Above that vmstat was showing high figures for si/so which is not a major suprise as such. If this only occurs on systems with large amounts of memory, could it be a variation of the excessive page-scanning problem that Rik has been on about? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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