From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx150.postini.com [74.125.245.150]) by kanga.kvack.org (Postfix) with SMTP id 9DC396B0037 for ; Fri, 22 Mar 2013 03:25:37 -0400 (EDT) Received: by mail-ee0-f54.google.com with SMTP id c41so2143455eek.13 for ; Fri, 22 Mar 2013 00:25:35 -0700 (PDT) Date: Fri, 22 Mar 2013 08:25:32 +0100 From: Ingo Molnar Subject: Re: [patch] mm: speedup in __early_pfn_to_nid Message-ID: <20130322072532.GC10608@gmail.com> References: <20130318155619.GA18828@sgi.com> <20130321105516.GC18484@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Russ Anderson , linux-mm@kvack.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com * David Rientjes wrote: > On Thu, 21 Mar 2013, Ingo Molnar wrote: > > > > Index: linux/mm/page_alloc.c > > > =================================================================== > > > --- linux.orig/mm/page_alloc.c 2013-03-18 10:52:11.510988843 -0500 > > > +++ linux/mm/page_alloc.c 2013-03-18 10:52:14.214931348 -0500 > > > @@ -4161,10 +4161,19 @@ int __meminit __early_pfn_to_nid(unsigne > > > { > > > unsigned long start_pfn, end_pfn; > > > int i, nid; > > > + static unsigned long last_start_pfn, last_end_pfn; > > > + static int last_nid; > > > > Please move these globals out of function local scope, to make it more > > apparent that they are not on-stack. I only noticed it in the second pass. > > The way they're currently defined places these in meminit.data as > appropriate; if they are moved out, please make sure to annotate their > definitions with __meminitdata. I'm fine with having them within the function as well in this special case, as long as a heavy /* NOTE: ... */ warning is put before them - which explains why these SMP-unsafe globals are safe. ( That warning will also act as a visual delimiter that breaks the normally confusing and misleading 'globals mixed amongst stack variables' pattern. ) Thanks, Ingo -- 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