From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 6C94E6B003D for ; Mon, 23 Mar 2009 11:21:34 -0400 (EDT) Date: Mon, 23 Mar 2009 17:29:54 +0100 From: Ingo Molnar Subject: Re: [aarcange@redhat.com: [PATCH] fork vs gup(-fast) fix] Message-ID: <20090323162954.GB4192@elte.hu> References: <20090318105735.BD17.A69D9226@jp.fujitsu.com> <20090322205249.6801.A69D9226@jp.fujitsu.com> <20090323091056.69DF.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090323091056.69DF.A69D9226@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Nick Piggin , Linus Torvalds , Andrea Arcangeli , Benjamin Herrenschmidt , Nick Piggin , Hugh Dickins , KAMEZAWA Hiroyuki , linux-mm@kvack.org List-ID: * KOSAKI Motohiro wrote: > > following patch is my v2 approach. > > it survive Andrea's three dio test-case. > > > > [...] > Frankly, linus sugessted to insert one branch into do_wp_page(), > but I remove one branch from gup_fast. > > I think it's good performance trade-off. but if anybody hate my > approach, I'll drop my chicken heart and try to linus suggested > way. We started out with a difficult corner case problem (for an arguably botched syscall promise we made to user-space many moons ago), and an invasive and unmaintainable looking patch: 8 files changed, 342 insertions(+), 77 deletions(-) And your v2 is now: 9 files changed, 66 insertions(+), 21 deletions(-) ... and it is also speeding up fast-gup. Which is a marked improvement IMO. Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org