Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 5 Aug 2002 14:03:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 5 Aug 2002 14:03:35 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:5382 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Mon, 5 Aug 2002 14:03:34 -0400 Message-ID: <3D4EC114.C87FEEFF@zip.com.au> Date: Mon, 05 Aug 2002 11:16:52 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-rc5 i686) X-Accept-Language: en MIME-Version: 1.0 To: Rik van Riel CC: Daniel Phillips , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Rmap speedup References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1441 Lines: 32 Rik van Riel wrote: > > On Mon, 5 Aug 2002, Daniel Phillips wrote: > > > > Despite the fact that the number of pte_chain references in > > > page_add/remove_rmap now just averages two in that test. > > > > It's weird that it only averages two. It's a four way and your running > > 10 in parallel, plus a process to watch for completion, right? > > I explained this one in the comment above the declaration of > struct pte_chain ;) > > * A singly linked list should be fine for most, if not all, workloads. > * On fork-after-exec the mapping we'll be removing will still be near > * the start of the list, on mixed application systems the short-lived > * processes will have their mappings near the start of the list and > * in systems with long-lived applications the relative overhead of > * exit() will be lower since the applications are long-lived. I don't think so - the list walks in there are fairly long. What seems to be happening is that, as Daniel mentioned, all the pte_chains for page N happen to have good locality with the pte_chains for page N+1. Like parallel lines. That might not hold up for longer-lived processes, slab cache fragmentation, longer chains, etc... - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/