From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 21 Nov 2007 15:29:42 -0800 (PST) From: Christoph Lameter Subject: Re: [PATCH] Page allocator: Get rid of the list of cold pages In-Reply-To: <20071121230041.GE31674@csn.ul.ie> Message-ID: References: <20071115162706.4b9b9e2a.akpm@linux-foundation.org> <20071121222059.GC31674@csn.ul.ie> <20071121230041.GE31674@csn.ul.ie> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: Andrew Morton , linux-mm@kvack.org, apw@shadowen.org, Martin Bligh List-ID: On Wed, 21 Nov 2007, Mel Gorman wrote: > > 2) it may be useful to do these tests with anonymous pages because the > > file handling paths are rather slow and you may not hit zone lock > > contention because there are other things in the way (radix tree?) > > I suspected this too, but thought if I went with anonymous pages we would > just get hit with mmap_sem instead and the results would not be significantly > different. I had also considered creating the files on tmpfs. In the end > I decided the original investigation was a filesystem and was as good a > starting point as any. Well you would get a hot cacheline with the semaphore. Its taken as a read lock so its not a holdoff in contrast to the zone lock where we actually spin until its available. In my experience it takes longer for the mmap sem cacheline to become a problem. -- 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