From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 2 Sep 2001 13:44:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 2 Sep 2001 13:44:49 -0400 Received: from humbolt.nl.linux.org ([131.211.28.48]:64786 "EHLO humbolt.nl.linux.org") by vger.kernel.org with ESMTP id ; Sun, 2 Sep 2001 13:44:38 -0400 Content-Type: text/plain; charset=US-ASCII From: Daniel Phillips To: Samium Gromoff <_deepfire@mail.ru> Subject: Re: Rik`s ac12-pmap2 vs ac12-vanilla perfcomp Date: Sun, 2 Sep 2001 19:51:50 +0200 X-Mailer: KMail [version 1.3.1] Cc: linux-kernel@vger.kernel.org In-Reply-To: <200109022146.f82LkS904034@-f> In-Reply-To: <200109022146.f82LkS904034@-f> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: <20010902174454Z16091-32383+3013@humbolt.nl.linux.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On September 2, 2001 11:46 pm, Samium Gromoff wrote: > Daniel Phillips wrote: > > > One thing that goes away with rmaps is the need to scan process page tables. > > It's possible that this takes enough load off L1 cache to produce the effects > > I feel like that. > actually there was a fear that the overhead of reverse map maintenance > will overthrow the gain on low loads, but in my case this isnt an issue. Rik's patch can be optimized a lot by using a direct pointer to the pte in the nonshared case, and perhaps a null rmap pointer in the kernel-only case (e.g., page cache). If the non-optimized version is already performing better than the traditional approach it's a very good sign. This needs careful confirmation. Measurements where you force your system into continuous swapping would be very interesting. -- Daniel