From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756609AbZDVUeq (ORCPT ); Wed, 22 Apr 2009 16:34:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754443AbZDVUee (ORCPT ); Wed, 22 Apr 2009 16:34:34 -0400 Received: from smtp-out.google.com ([216.239.45.13]:49921 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751688AbZDVUed (ORCPT ); Wed, 22 Apr 2009 16:34:33 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=kticdTxqoKuvAhaz1tn8vOcGNEM6TZXfZwou4mH0kS6vnWvaIwXsO6D6qGJJvmksA SnHx504TxdE8ohnuEg4cw== Date: Wed, 22 Apr 2009 13:34:27 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Lee Schermerhorn cc: Mel Gorman , Linux Memory Management List , KOSAKI Motohiro , Christoph Lameter , Nick Piggin , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra , Pekka Enberg , Andrew Morton Subject: Re: [PATCH 16/22] Do not setup zonelist cache when there is only one node In-Reply-To: <1240432339.22694.64.camel@lts-notebook> Message-ID: References: <1240408407-21848-1-git-send-email-mel@csn.ul.ie> <1240408407-21848-17-git-send-email-mel@csn.ul.ie> <1240432339.22694.64.camel@lts-notebook> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 22 Apr 2009, Lee Schermerhorn wrote: > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > index 7f45de1..e59bb80 100644 > > > --- a/mm/page_alloc.c > > > +++ b/mm/page_alloc.c > > > @@ -1467,8 +1467,11 @@ this_zone_full: > > > if (NUMA_BUILD) > > > zlc_mark_zone_full(zonelist, z); > > > > If zonelist caching is never used for UMA machines, why should they ever > > call zlc_mark_zone_full()? It will always dereference > > zonelist->zlcache_ptr and immediately return without doing anything. > > > > Wouldn't it better to just add > > > > if (num_online_nodes() == 1) > > continue; > > > > right before this call to zlc_mark_zone_full()? This should compile out > > the remainder of the loop for !CONFIG_NUMA kernels anyway. > > Shouldn't it already do that? NUMA_BUILD is defined as 0 when > !CONFIG_NUMA to avoid #ifdef's in the code while still allowing compiler > error checking in the dead code. > Yeah, but adding the check on num_online_nodes() also prevents needlessly calling zlc_mark_zone_full() on CONFIG_NUMA kernels when running on an UMA machine. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 154BA6B0105 for ; Wed, 22 Apr 2009 16:34:03 -0400 (EDT) Received: from zps19.corp.google.com (zps19.corp.google.com [172.25.146.19]) by smtp-out.google.com with ESMTP id n3MKYTo3017106 for ; Wed, 22 Apr 2009 21:34:30 +0100 Received: from rv-out-0708.google.com (rvfc5.prod.google.com [10.140.180.5]) by zps19.corp.google.com with ESMTP id n3MKYR2e026724 for ; Wed, 22 Apr 2009 13:34:28 -0700 Received: by rv-out-0708.google.com with SMTP id c5so139217rvf.14 for ; Wed, 22 Apr 2009 13:34:27 -0700 (PDT) Date: Wed, 22 Apr 2009 13:34:27 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH 16/22] Do not setup zonelist cache when there is only one node In-Reply-To: <1240432339.22694.64.camel@lts-notebook> Message-ID: References: <1240408407-21848-1-git-send-email-mel@csn.ul.ie> <1240408407-21848-17-git-send-email-mel@csn.ul.ie> <1240432339.22694.64.camel@lts-notebook> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Lee Schermerhorn Cc: Mel Gorman , Linux Memory Management List , KOSAKI Motohiro , Christoph Lameter , Nick Piggin , Linux Kernel Mailing List , Lin Ming , Zhang Yanmin , Peter Zijlstra , Pekka Enberg , Andrew Morton List-ID: On Wed, 22 Apr 2009, Lee Schermerhorn wrote: > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > index 7f45de1..e59bb80 100644 > > > --- a/mm/page_alloc.c > > > +++ b/mm/page_alloc.c > > > @@ -1467,8 +1467,11 @@ this_zone_full: > > > if (NUMA_BUILD) > > > zlc_mark_zone_full(zonelist, z); > > > > If zonelist caching is never used for UMA machines, why should they ever > > call zlc_mark_zone_full()? It will always dereference > > zonelist->zlcache_ptr and immediately return without doing anything. > > > > Wouldn't it better to just add > > > > if (num_online_nodes() == 1) > > continue; > > > > right before this call to zlc_mark_zone_full()? This should compile out > > the remainder of the loop for !CONFIG_NUMA kernels anyway. > > Shouldn't it already do that? NUMA_BUILD is defined as 0 when > !CONFIG_NUMA to avoid #ifdef's in the code while still allowing compiler > error checking in the dead code. > Yeah, but adding the check on num_online_nodes() also prevents needlessly calling zlc_mark_zone_full() on CONFIG_NUMA kernels when running on an UMA machine. -- 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