Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752564Ab2KTVtf (ORCPT ); Tue, 20 Nov 2012 16:49:35 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:39289 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751462Ab2KTVte (ORCPT ); Tue, 20 Nov 2012 16:49:34 -0500 Date: Tue, 20 Nov 2012 13:49:32 -0800 From: Andrew Morton To: David Rientjes Cc: Johannes Weiner , Michal Hocko , KAMEZAWA Hiroyuki , Hugh Dickins , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch] mm, memcg: avoid unnecessary function call when memcg is disabled Message-Id: <20121120134932.055bc192.akpm@linux-foundation.org> In-Reply-To: References: 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 Content-Length: 1524 Lines: 40 On Mon, 19 Nov 2012 17:44:34 -0800 (PST) David Rientjes wrote: > While profiling numa/core v16 with cgroup_disable=memory on the command > line, I noticed mem_cgroup_count_vm_event() still showed up as high as > 0.60% in perftop. > > This occurs because the function is called extremely often even when memcg > is disabled. > > To fix this, inline the check for mem_cgroup_disabled() so we avoid the > unnecessary function call if memcg is disabled. > > ... > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -181,7 +181,14 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, > gfp_t gfp_mask, > unsigned long *total_scanned); > > -void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx); > +void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx); > +static inline void mem_cgroup_count_vm_event(struct mm_struct *mm, > + enum vm_event_item idx) > +{ > + if (mem_cgroup_disabled() || !mm) > + return; > + __mem_cgroup_count_vm_event(mm, idx); > +} Does the !mm case occur frequently enough to justify inlining it, or should that test remain out-of-line? -- 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/