Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752247AbcCGEUi (ORCPT ); Sun, 6 Mar 2016 23:20:38 -0500 Received: from LGEAMRELO11.lge.com ([156.147.23.51]:35251 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752077AbcCGEUT (ORCPT ); Sun, 6 Mar 2016 23:20:19 -0500 X-Original-SENDERIP: 156.147.1.126 X-Original-MAILFROM: iamjoonsoo.kim@lge.com X-Original-SENDERIP: 10.177.222.138 X-Original-MAILFROM: iamjoonsoo.kim@lge.com Date: Mon, 7 Mar 2016 13:20:55 +0900 From: Joonsoo Kim To: Andrew Morton Cc: Vlastimil Babka , Michal Nazarewicz , Minchan Kim , Mel Gorman , "Kirill A. Shutemov" , Sergey Senozhatsky , Steven Rostedt , Linux Memory Management List , LKML , linux-api@vger.kernel.org Subject: Re: [PATCH v4 2/2] mm/page_ref: add tracepoint to track down page reference manipulation Message-ID: <20160307042054.GA24602@js1304-P5Q-DELUXE> References: <1456448282-897-1-git-send-email-iamjoonsoo.kim@lge.com> <1456448282-897-2-git-send-email-iamjoonsoo.kim@lge.com> <56D71BB2.5060503@suse.cz> <20160304120439.a38a15e0fe5b989fe5b8edfc@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160304120439.a38a15e0fe5b989fe5b8edfc@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2802 Lines: 70 On Fri, Mar 04, 2016 at 12:04:39PM -0800, Andrew Morton wrote: > On Thu, 3 Mar 2016 16:43:49 +0900 Joonsoo Kim wrote: > > > > Acked-by: Vlastimil Babka > > > > > >> +config DEBUG_PAGE_REF > > >> + bool "Enable tracepoint to track down page reference manipulation" > > >> + depends on DEBUG_KERNEL > > >> + depends on TRACEPOINTS > > >> + ---help--- > > >> + This is the feature to add tracepoint for tracking down page > > >> reference > > >> + manipulation. This tracking is useful to diagnosis functional > > >> failure > > >> + due to migration failure caused by page reference mismatch. Be > > > > > > > > > OK. > > > > > >> + careful to turn on this feature because it could bloat some > > >> kernel > > >> + text. In my configuration, it bloats 30 KB. Although kernel text > > >> will > > >> + be bloated, there would be no runtime performance overhead if > > >> + tracepoint isn't enabled thanks to jump label. > > > > > > > > > I would just write something like: > > > > > > Enabling this feature adds about 30 KB to the kernel code, but runtime > > > performance overhead is virtually none until the tracepoints are actually > > > enabled. > > > > Okay, better! > > Andrew, do you want fixup patch from me or could you simply handle it? > > > > This? Yep! Thanks! > > --- a/mm/Kconfig.debug~mm-page_ref-add-tracepoint-to-track-down-page-reference-manipulation-fix-3-fix > +++ a/mm/Kconfig.debug > @@ -82,10 +82,9 @@ config DEBUG_PAGE_REF > depends on DEBUG_KERNEL > depends on TRACEPOINTS > ---help--- > - This is the feature to add tracepoint for tracking down page reference > - manipulation. This tracking is useful to diagnosis functional failure > - due to migration failure caused by page reference mismatch. Be > - careful to turn on this feature because it could bloat some kernel > - text. In my configuration, it bloats 30 KB. Although kernel text will > - be bloated, there would be no runtime performance overhead if > - tracepoint isn't enabled thanks to jump label. > + This is a feature to add tracepoint for tracking down page reference > + manipulation. This tracking is useful to diagnose functional failure > + due to migration failures caused by page reference mismatches. Be > + careful when enabling this feature because it adds about 30 KB to the > + kernel code. However the runtime performance overhead is virtually > + nil until the tracepoints are actually enabled. > _ > > -- > 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