From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935542Ab2JXUZz (ORCPT ); Wed, 24 Oct 2012 16:25:55 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:41602 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933652Ab2JXUZy (ORCPT ); Wed, 24 Oct 2012 16:25:54 -0400 Date: Wed, 24 Oct 2012 13:25:52 -0700 From: Andrew Morton To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , Andrea Arcangeli , linux-mm@kvack.org, Andi Kleen , "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 10/10] thp: implement refcounting for huge zero page Message-Id: <20121024132552.5f9a5f5b.akpm@linux-foundation.org> In-Reply-To: <20121024194552.GA24460@otc-wbsnb-06> References: <1350280859-18801-1-git-send-email-kirill.shutemov@linux.intel.com> <1350280859-18801-11-git-send-email-kirill.shutemov@linux.intel.com> <20121018164502.b32791e7.akpm@linux-foundation.org> <20121018235941.GA32397@shutemov.name> <20121023063532.GA15870@shutemov.name> <20121022234349.27f33f62.akpm@linux-foundation.org> <20121023070018.GA18381@otc-wbsnb-06> <20121023155915.7d5ef9d1.akpm@linux-foundation.org> <20121023233801.GA21591@shutemov.name> <20121024122253.5ecea992.akpm@linux-foundation.org> <20121024194552.GA24460@otc-wbsnb-06> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 24 Oct 2012 22:45:52 +0300 "Kirill A. Shutemov" wrote: > On Wed, Oct 24, 2012 at 12:22:53PM -0700, Andrew Morton wrote: > > > > I'm thinking that such a workload would be the above dd in parallel > > with a small app which touches the huge page and then exits, then gets > > executed again. That "small app" sounds realistic to me. Obviously > > one could exercise the zero page's refcount at higher frequency with a > > tight map/touch/unmap loop, but that sounds less realistic. It's worth > > trying that exercise as well though. > > > > Or do something else. But we should try to probe this code's > > worst-case behaviour, get an understanding of its effects and then > > decide whether any such workload is realisic enough to worry about. > > Okay, I'll try few memory pressure scenarios. Thanks. > Meanwhile, could you take patches 01-09? Patch 09 implements simpler > allocation scheme. It would be nice to get all other code tested. > Or do you see any other blocker? I think I would take them all, to get them tested while we're still poking at the code. It's a matter of getting my lazy ass onto reviewing the patches. The patches have a disturbing lack of reviewed-by's, acked-by's and tested-by's on them. Have any other of the MM lazy asses actually spent some time with them yet?