Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761541AbXEPA2Y (ORCPT ); Tue, 15 May 2007 20:28:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758999AbXEPA2S (ORCPT ); Tue, 15 May 2007 20:28:18 -0400 Received: from smtp106.mail.mud.yahoo.com ([209.191.85.216]:36404 "HELO smtp106.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758793AbXEPA2R (ORCPT ); Tue, 15 May 2007 20:28:17 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=oSeNHud+25jQbSTAHZsL5WD0kVmOx3JhFaIu7jlwhKl9pITw+s/dBrl3N1JhiJ/HjuZbDavZ5mtoTOTmB8D7fqmjkX5/BA80Fn5Ea3brT1v1V6BwAHnE0dnzdJIyasYcOpoHWpTkhWMYWHP5mWDryV8LO8LQnScb7NCinUxPG7s= ; X-YMail-OSG: XRQ.afoVM1mIjMlJFMRi6ozZukhsIymADCVlmF3cxpaCCVZMP426AscqPxJZ1o0i7W0fAKw8Rw-- Message-ID: <464A501A.3080209@yahoo.com.au> Date: Wed, 16 May 2007 10:28:10 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Andrew Morton CC: Theodore Tso , Fengguang Wu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Rik van Riel , "linux-ext4@vger.kernel.org" Subject: Re: [PATCH] resolve duplicate flag no for PG_lazyfree References: <379110250.28666@ustc.edu.cn> <20070513224630.3cd0cb54.akpm@linux-foundation.org> <20070514180618.GB9399@thunk.org> <20070514134606.695f087a.akpm@linux-foundation.org> In-Reply-To: <20070514134606.695f087a.akpm@linux-foundation.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1996 Lines: 54 Andrew Morton wrote: > On Mon, 14 May 2007 14:06:19 -0400 > Theodore Tso wrote: > > >>On Sun, May 13, 2007 at 10:46:30PM -0700, Andrew Morton wrote: >> >>>otoh, the intersection between pages which are PageBooked() and pages which >>>are PageLazyFree() should be zreo, so it'd be good to actually formalise >>>this reuse within the ext4 patches. >>> >>>otoh2, PageLazyFree() could have reused PG_owner_priv_1. >>> >>>Rik, Ted: any thoughts? We do need to scrimp on page flags: when we >>>finally run out, we're screwed. >> >>It makes sense to me. PG_lazyfree is currently only in -mm, right? > > > Ah, yes, I got confused, sorry. > > >> I >>don't see it in my git tree. It would probably would be a good idea >>to make sure that we check to add some sanity checking code if it >>isn't there already that PG_lazyfree isn't already set when try to set >>PG_lazyfree (just in case there is a bug in the future which causes >>the should-never-happen case of trying lazy free a PageBooked page). >> > > > Actually, I think the current status of > lazy-freeing-of-memory-through-madv_free.patch is "might not be needed". I > _think_ we've determined that 0a27a14a62921b438bb6f33772690d345a089be6 > sufficiently fixed the perfomance problems we had in there? I think so far we've found that it fixes the MySQL scalability problem, yes. I couldn't see any statistically significant difference with MySQL in my tests with MADV_FREE (versus MADV_DONTNEED). ebizzy is improved a bit at low concurrency but drops off slightly at higher concurrency. But basically, I don't think we've found a good reason to use a page flag and introduce the potential performance regressions that the MADV_FREE patch has. -- SUSE Labs, Novell Inc. - 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/