From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 16 Oct 2006 18:10:20 -0700 From: Andrew Morton Subject: Re: Page allocator: Single Zone optimizations Message-Id: <20061016181020.7fbd9915.akpm@osdl.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: linux-mm@kvack.org List-ID: On Mon, 16 Oct 2006 17:50:26 -0700 (PDT) Christoph Lameter wrote: > The current code in 2.6.19-rc1-mm1 already allows the configuration of a > system with a single zone. We observed significant performance gains which > were likely due to the reduced cache footprint (removal of the zone_table > also contributed). > > This patch continues that line of work making the zone protection logic > optional throwing out moreVM overhead that is not needed in the single > zone case (which hopefully in the far future most of us will be able to > use). > > Also several macros can become constant if we know that only > a single zone exists (ZONES_SHIFT == 0) which will remove more code > from the VM and avoid runtime branching. akpm:/home/akpm> grep '^+#if' x +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT == 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 +#if ZONES_SHIFT > 0 Now that just goes too far. -- 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