Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262696AbUCEUdB (ORCPT ); Fri, 5 Mar 2004 15:33:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262698AbUCEUdB (ORCPT ); Fri, 5 Mar 2004 15:33:01 -0500 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:8715 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S262696AbUCEUc7 (ORCPT ); Fri, 5 Mar 2004 15:32:59 -0500 Date: Fri, 5 Mar 2004 21:33:40 +0100 From: Andrea Arcangeli To: Jamie Lokier Cc: Andrew Morton , peter@mysql.com, riel@redhat.com, mbligh@aracnet.com, linux-kernel@vger.kernel.org Subject: Re: 2.4.23aa2 (bugfixes and important VM improvements for the high end) Message-ID: <20040305203340.GU4922@dualathlon.random> References: <20040228072926.GR8834@dualathlon.random> <20040229014357.GW8834@dualathlon.random> <1078370073.3403.759.camel@abyss.local> <20040303193343.52226603.akpm@osdl.org> <1078371876.3403.810.camel@abyss.local> <20040303200704.17d81bda.akpm@osdl.org> <20040304045212.GG4922@dualathlon.random> <20040303211042.33cd15ce.akpm@osdl.org> <20040305201954.GB7254@mail.shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040305201954.GB7254@mail.shareable.org> User-Agent: Mutt/1.4.1i X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 979 Lines: 19 On Fri, Mar 05, 2004 at 08:19:55PM +0000, Jamie Lokier wrote: > Andrew Morton wrote: > > We believe that this could cause misbehaviour of such things as the > > boehm garbage collector. This patch provides the mprotect() atomicity by > > performing all userspace copies under page_table_lock. > > Can you use a read-write lock, so that userspace copies only need to > take the lock for reading? That doesn't eliminate cacheline bouncing > but does eliminate the serialisation. normally the bouncing would be the only overhead, but here I also think the serialization is a significant factor of the contention because the critical section is taking lots of time. So I would expect some improvement by using a read/write lock. - 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/