From mboxrd@z Thu Jan 1 00:00:00 1970 From: Con Kolivas Subject: Re: [PATCH] mm: yield during swap prefetching Date: Wed, 8 Mar 2006 12:28:05 +1100 References: <200603081013.44678.kernel@kolivas.org> <200603081212.03223.kernel@kolivas.org> <20060307172337.1d97cd80.akpm@osdl.org> In-Reply-To: <20060307172337.1d97cd80.akpm@osdl.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200603081228.05820.kernel@kolivas.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, ck@vds.kolivas.org List-ID: On Wed, 8 Mar 2006 12:23 pm, Andrew Morton wrote: > Con Kolivas wrote: > > > but, but. If prefetching is prefetching stuff which that game will > > > soon use then it'll be an aggregate improvement. If prefetch is > > > prefetching stuff which that game _won't_ use then prefetch is busted. > > > Using yield() to artificially cripple kprefetchd is a rather sad > > > workaround isn't it? > > > > It's not the stuff that it prefetches that's the problem; it's the disk > > access. > > But the prefetch code tries to avoid prefetching when the disk is otherwise > busy (or it should - we discussed that a bit a while ago). Anything that does disk access delays prefetch fine. Things that only do heavy cpu do not delay prefetch. Anything reading from disk will be noticeable during 3d gaming. > Sorry, I'm not trying to be awkward here - I think that nobbling prefetch > when there's a lot of CPU activity is just the wrong thing to do and it'll > harm other workloads. I can't distinguish between when cpu activity is important (game) and when it is not (compile), and assuming worst case scenario and not doing any swap prefetching is my intent. I could add cpu accounting to prefetch_suitable() instead, but that gets rather messy and yielding achieves the same endpoint. Cheers, Con -- 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