From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from calculon.skynet.ie (calculon.skynet.ie [193.1.99.88]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 0939467B44 for ; Thu, 8 Jun 2006 02:25:39 +1000 (EST) Date: Wed, 7 Jun 2006 17:25:33 +0100 (IST) From: Mel Gorman To: Andi Kleen Subject: Re: [PATCH 0/5] Sizing zones and holes in an architecture independent manner V7 In-Reply-To: <200606071720.22242.ak@suse.de> Message-ID: References: <20060606134710.21419.48239.sendpatchset@skynet.skynet.ie> <200606071216.24640.ak@suse.de> <200606071720.22242.ak@suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Andrew Morton , davej@codemonkey.org.uk, tony.luck@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bob.picco@hp.com, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 7 Jun 2006, Andi Kleen wrote: > >> Ok, while true, I'm not sure how it affects performance. The only "real" >> value affected by present_pages is the number of patches that are >> allocated in batches to the per-cpu allocator. > > It affects the low/high water marks in the VM zone balancer. > ok, that's true. The watermarks would be higher if memmap and the kernel image is not taken into account. Arguably, the same applies to bootmem allocations. This hits all architectures *except* x86_64. > Especially for the 16MB DMA zone it can make a difference if you > account 4MB kernel in there or not. > I'm guessing it's a difficult-to-trigger problem or it would have been reported for other arches. Assuming it can be triggered and that is what was causing your problems, it's still worth fixing in the arch-independent code rather than burying it in arch/somewhere, right? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab