From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 12 Nov 2007 16:37:28 -0800 (PST) From: Christoph Lameter Subject: Re: [patch 3/6] mm: speculative get page In-Reply-To: <20071113003525.GD30650@wotan.suse.de> Message-ID: References: <20071111084556.GC19816@wotan.suse.de> <20071111085004.GF19816@wotan.suse.de> <20071113003525.GD30650@wotan.suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Andrew Morton , Linus Torvalds , Peter Zijlstra , Hugh Dickins , Linux Memory Management List List-ID: On Tue, 13 Nov 2007, Nick Piggin wrote: > > Good idea. That avoids another page bit. > > Yeah, it's Hugh's good idea. It avoids smp_rmb() in the find_get_page > path as well, which will be helpful at least for things like powerpc > and ia64, if not x86. At one single atomic operation to lookup and take > a reference on a pagecache page, I think it is approaching the fastest > possible implementation ;) Well I hope all locations that do get_page_unless_zero are aware that a failure does not mean that the page is being freed. > > Looks okay but I think you could remove the earlier performance check. We > > already modified the page struct by obtaining the page lock so we hold it > > exclusively. And the failure rate here is typicalyvery low. > > It's up to you. Honestly, I don't have good test facilities for page > migration. If it's all the same to you, do you mind if we leave it like > this, and then you can change it in future? Ok. Lee will likely get to that ;-). -- 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