From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 21 Nov 2007 23:51:14 +0000 From: Mel Gorman Subject: Re: [PATCH] Page allocator: Get rid of the list of cold pages Message-ID: <20071121235114.GF31674@csn.ul.ie> References: <20071115162706.4b9b9e2a.akpm@linux-foundation.org> <20071121222059.GC31674@csn.ul.ie> <20071121152328.72697909.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20071121152328.72697909.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: clameter@sgi.com, linux-mm@kvack.org, apw@shadowen.org, mbligh@mbligh.org List-ID: On (21/11/07 15:23), Andrew Morton didst pronounce: > On Wed, 21 Nov 2007 22:20:59 +0000 > Mel Gorman wrote: > > > I cannot see the evidence of this 3x improvement around the 32K filesize > > mark. It may be because my test is very different to what happened before, > > I got something wrong or the per-CPU allocator is not as good as it used to > > be and does not give out the same hot-pages all the time. > > Could be that when you return a handful of pages to the page allocator > and then allocate a handful of pages, you get the same pages back. But > that the page allocator wasn't doing that 4-5 years ago when that code > went in. > Maybe. > Of course, even if the page allocator is indeed doing this for us, you'd > still expect to see benefits from the per-cpu magazines when each CPU is > allocating and freeing a number of pages which is close to the size of > that CPU's L1 cache. Because when the pages are going into and coming from > a shared-by-all-cpus pool, each CPU will often get pages which are hot in > a different cpu's L1. > I checked and I am not seeing any clear benefit around the size of the L1 cache (64K D-cache). It could be because the granularity of the time is too low and the cost of zeroing the page is drowning everything else out in this test. -- 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