Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263079AbUKTBe5 (ORCPT ); Fri, 19 Nov 2004 20:34:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263067AbUKTBam (ORCPT ); Fri, 19 Nov 2004 20:30:42 -0500 Received: from zeus.kernel.org ([204.152.189.113]:26840 "EHLO zeus.kernel.org") by vger.kernel.org with ESMTP id S263079AbUKTB3w (ORCPT ); Fri, 19 Nov 2004 20:29:52 -0500 Date: Fri, 19 Nov 2004 17:29:06 -0800 (PST) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Nick Piggin cc: Linus Torvalds , akpm@osdl.org, Benjamin Herrenschmidt , Hugh Dickins , linux-mm@kvack.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: page fault scalability patch V11 [0/7]: overview In-Reply-To: <419E98E7.1080402@yahoo.com.au> Message-ID: References: <419D581F.2080302@yahoo.com.au> <419D5E09.20805@yahoo.com.au> <1100848068.25520.49.camel@gaston> <419E98E7.1080402@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1106 Lines: 24 On Sat, 20 Nov 2004, Nick Piggin wrote: > I think this sounds like it might be a good idea. I prefer it to having > the unbounded error of sloppy rss (as improbable as it may be in practice). It may also be faster since the processors can have exclusive cache lines. This means we need to move rss into the task struct. But how does one get from mm struct to task struct? current is likely available most of the time. Is that always the case? > The per thread rss may wrap (maybe not 64-bit counters), but even so, > the summation over all threads should still end up being correct I > think. Note though that the mmap_sem is no protection. It is a read lock and may be held by multiple processes while incrementing and decrementing rss. This is likely reducing the number of collisions significantly but it wont be a guarantee like locking or atomic ops. - 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/