From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx198.postini.com [74.125.245.198]) by kanga.kvack.org (Postfix) with SMTP id 7C8646B0033 for ; Tue, 3 Sep 2013 18:47:49 -0400 (EDT) Date: Tue, 3 Sep 2013 18:47:31 -0400 From: Johannes Weiner Subject: Re: [PATCH RESEND] mm/vmscan : use vmcan_swappiness( ) basing on MEMCG config to elimiate unnecessary runtime cost Message-ID: <20130903224731.GC1412@cmpxchg.org> References: <20130826133658.GA357@larmbr-lcx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130826133658.GA357@larmbr-lcx> Sender: owner-linux-mm@kvack.org List-ID: To: larmbr Cc: linux-mm@kvack.org, mhocko@suse.cz, bsingharora@gmail.com, kamezawa.hiroyu@jp.fujitsu.com, akpm@linux-foundation.org, mgorman@suse.de, riel@redhat.com, linux-kernel@vger.kernel.org On Mon, Aug 26, 2013 at 09:36:58PM +0800, larmbr wrote: > Currently, we get the vm_swappiness via vmscan_swappiness(), which > calls global_reclaim() to check if this is a global reclaim. > > Besides, the current implementation of global_reclaim() always returns > true for the !CONFIG_MEGCG case, and judges the other case by checking > whether scan_control->target_mem_cgroup is null or not. > > Thus, we could just use two versions of vmscan_swappiness() based on > MEMCG Kconfig , to eliminate the unnecessary run-time cost for > the !CONFIG_MEMCG at all, and to squash all memcg-related checking > into the CONFIG_MEMCG version. The compiler can easily detect that global_reclaim() always returns true for !CONFIG_MEMCG during compile time and not even generate a branch for this. > 2 files changed, 12 insertions(+), 3 deletions(-) You're adding more code for now gain. -- 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