From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx155.postini.com [74.125.245.155]) by kanga.kvack.org (Postfix) with SMTP id 58B9F6B002B for ; Mon, 17 Dec 2012 08:58:43 -0500 (EST) Received: by mail-ob0-f169.google.com with SMTP id v19so6298384obq.14 for ; Mon, 17 Dec 2012 05:58:42 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20121212201529.GD16230@one.firstfloor.org> References: <1355331819-8728-1-git-send-email-js1304@gmail.com> <0000013b90beeb93-87f65a09-0cc3-419f-be26-5271148cb947-000000@email.amazonses.com> <20121212201529.GD16230@one.firstfloor.org> Date: Mon, 17 Dec 2012 22:58:42 +0900 Message-ID: Subject: Re: [PATCH] mm: introduce numa_zero_pfn From: JoonSoo Kim Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Andi Kleen Cc: Christoph Lameter , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" 2012/12/13 Andi Kleen : >> I would expect a processor to fetch the zero page cachelines from the l3 >> cache from other sockets avoiding memory transactions altogether. The zero >> page is likely in use somewhere so no typically no memory accesses should >> occur in a system. > > It depends on how effectively the workload uses the caches. If something > is a cache pig of the L3 cache, then even shareable cache lines may need > to be refetched regularly. > > But if your workloads spends a significant part of its time reading > from zero page read only data there is something wrong with the workload. > > I would do some data profiling first to really prove that is the case. Okay. I didn't know about L3 cache, before. Now, I think that I need some data profiling! Thanks for comment. -- 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