From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759091AbXENWsL (ORCPT ); Mon, 14 May 2007 18:48:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754113AbXENWr7 (ORCPT ); Mon, 14 May 2007 18:47:59 -0400 Received: from mail13.syd.optusnet.com.au ([211.29.132.194]:60200 "EHLO mail13.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753827AbXENWr6 (ORCPT ); Mon, 14 May 2007 18:47:58 -0400 From: Con Kolivas To: Andrew Morton Subject: Re: [PATCH] mm: swap prefetch more improvements Date: Tue, 15 May 2007 08:43:35 +1000 User-Agent: KMail/1.9.5 Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, ck@vds.kolivas.org References: <200705141050.55038.kernel@kolivas.org> <20070514150032.d3ef6bb1.akpm@linux-foundation.org> In-Reply-To: <20070514150032.d3ef6bb1.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200705150843.36721.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 15 May 2007 08:00, Andrew Morton wrote: > On Mon, 14 May 2007 10:50:54 +1000 > > Con Kolivas wrote: > > akpm, please queue on top of "mm: swap prefetch improvements" > > > > --- > > Failed radix_tree_insert wasn't being handled leaving stale kmem. > > > > The list should be iterated over in the reverse order when prefetching. > > > > Make the yield within kprefetchd stronger through the use of > > cond_resched. > > hm. > > > - might_sleep(); > > - if (!prefetch_suitable()) > > + /* Yield to anything else running */ > > + if (cond_resched() || !prefetch_suitable()) > > goto out_unlocked; > > So if cond_resched() happened to schedule away, we terminate this > swap-tricking attempt. It's not possible to determine the reasons for this > from the code or from the changelog (==bad). > > How come? Hmm I thought the line above that says "yield to anything else running" was explicit enough. The idea is kprefetchd shouldn't run if any other real activity is happening just about anywhere, and a positive cond_resched would indicate likely activity so we just put kprefetchd back to sleep. -- -ck