Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965110AbbESPYf (ORCPT ); Tue, 19 May 2015 11:24:35 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:35222 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933034AbbESPYa (ORCPT ); Tue, 19 May 2015 11:24:30 -0400 Date: Tue, 19 May 2015 17:27:10 +0200 From: Michal Hocko To: Mel Gorman Cc: Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Tejun Heo , cgroups@vger.kernel.org Subject: Re: [PATCH] mm, memcg: Optionally disable memcg by default using Kconfig Message-ID: <20150519152710.GK6203@dhcp22.suse.cz> References: <20150519104057.GC2462@suse.de> <20150519141807.GA9788@cmpxchg.org> <20150519145340.GI6203@dhcp22.suse.cz> <20150519151302.GG2462@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150519151302.GG2462@suse.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1623 Lines: 33 On Tue 19-05-15 16:13:02, Mel Gorman wrote: [...] > :ffffffff811c160f: je ffffffff811c1630 > :ffffffff811c1611: xor %eax,%eax > :ffffffff811c1613: xor %ebx,%ebx > 1 1.7e-05 :ffffffff811c1615: mov %rbx,(%r12) > 7 1.2e-04 :ffffffff811c1619: add $0x10,%rsp > 1211 0.0203 :ffffffff811c161d: pop %rbx > 5 8.4e-05 :ffffffff811c161e: pop %r12 > 5 8.4e-05 :ffffffff811c1620: pop %r13 > 1249 0.0210 :ffffffff811c1622: pop %r14 > 7 1.2e-04 :ffffffff811c1624: pop %rbp > 5 8.4e-05 :ffffffff811c1625: retq > :ffffffff811c1626: nopw %cs:0x0(%rax,%rax,1) > 295 0.0050 :ffffffff811c1630: mov (%rdi),%rax > 160703 2.6973 :ffffffff811c1633: mov %edx,%r13d Huh, what? Even if this was off by one and the preceding instruction has consumed the time. This would be reading from page->flags but the page should be hot by the time we got here, no? > #### MEL: I was surprised to see this atrocity. It's a PageSwapCache check > #### /usr/src/linux-4.0-vanilla/./arch/x86/include/asm/bitops.h:311 > #### /usr/src/linux-4.0-vanilla/include/linux/page-flags.h:261 > #### /usr/src/linux-4.0-vanilla/mm/memcontrol.c:5473 -- Michal Hocko SUSE Labs -- 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/