From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754350Ab0CWSOt (ORCPT ); Tue, 23 Mar 2010 14:14:49 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:57948 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754247Ab0CWSOr (ORCPT ); Tue, 23 Mar 2010 14:14:47 -0400 Date: Tue, 23 Mar 2010 11:13:51 -0700 From: Andrew Morton To: Ingo Molnar Cc: Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bugzilla-daemon@bugzilla.kernel.org, bugme-daemon@bugzilla.kernel.org, ant.starikov@gmail.com, Peter Zijlstra Subject: Re: [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression in performance Message-Id: <20100323111351.756c8752.akpm@linux-foundation.org> In-Reply-To: <20100323173409.GA24845@elte.hu> References: <20100323102208.512c16cc.akpm@linux-foundation.org> <20100323173409.GA24845@elte.hu> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.9; 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 Tue, 23 Mar 2010 18:34:09 +0100 Ingo Molnar wrote: > > It shows a very brutal amount of page fault invoked mmap_sem spinning > overhead. > Yes. Note that we fall off a cliff at nine threads on a 16-way. As soon as a core gets two threads scheduled onto it? Probably triggered by an MM change, possibly triggered by a sched change which tickled a preexisting MM shortcoming. Who knows. Anton, we have an executable binary in the bugzilla report but it would be nice to also have at least a description of what that code is actually doing. A quick strace shows quite a lot of mprotect activity. A pseudo-code walkthrough, perhaps? Thanks. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 252096B01C5 for ; Tue, 23 Mar 2010 14:14:47 -0400 (EDT) Date: Tue, 23 Mar 2010 11:13:51 -0700 From: Andrew Morton Subject: Re: [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression in performance Message-Id: <20100323111351.756c8752.akpm@linux-foundation.org> In-Reply-To: <20100323173409.GA24845@elte.hu> References: <20100323102208.512c16cc.akpm@linux-foundation.org> <20100323173409.GA24845@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Ingo Molnar Cc: Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bugzilla-daemon@bugzilla.kernel.org, bugme-daemon@bugzilla.kernel.org, ant.starikov@gmail.com, Peter Zijlstra List-ID: On Tue, 23 Mar 2010 18:34:09 +0100 Ingo Molnar wrote: > > It shows a very brutal amount of page fault invoked mmap_sem spinning > overhead. > Yes. Note that we fall off a cliff at nine threads on a 16-way. As soon as a core gets two threads scheduled onto it? Probably triggered by an MM change, possibly triggered by a sched change which tickled a preexisting MM shortcoming. Who knows. Anton, we have an executable binary in the bugzilla report but it would be nice to also have at least a description of what that code is actually doing. A quick strace shows quite a lot of mprotect activity. A pseudo-code walkthrough, perhaps? Thanks. -- 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