From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f171.google.com (mail-pf0-f171.google.com [209.85.192.171]) by kanga.kvack.org (Postfix) with ESMTP id D60886B0298 for ; Thu, 18 Feb 2016 19:33:04 -0500 (EST) Received: by mail-pf0-f171.google.com with SMTP id x65so40647983pfb.1 for ; Thu, 18 Feb 2016 16:33:04 -0800 (PST) Received: from mail-pa0-x22b.google.com (mail-pa0-x22b.google.com. [2607:f8b0:400e:c03::22b]) by mx.google.com with ESMTPS id r15si12538045pfr.8.2016.02.18.16.33.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Feb 2016 16:33:04 -0800 (PST) Received: by mail-pa0-x22b.google.com with SMTP id fl4so39986797pad.0 for ; Thu, 18 Feb 2016 16:33:04 -0800 (PST) Date: Fri, 19 Feb 2016 09:34:21 +0900 From: Sergey Senozhatsky Subject: Re: [PATCH 2/2] mm/page_ref: add tracepoint to track down page reference manipulation Message-ID: <20160219003421.GA587@swordfish> References: <1455505490-12376-1-git-send-email-iamjoonsoo.kim@lge.com> <1455505490-12376-2-git-send-email-iamjoonsoo.kim@lge.com> <20160218092926.083ca007@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160218092926.083ca007@gandalf.local.home> Sender: owner-linux-mm@kvack.org List-ID: To: Steven Rostedt Cc: js1304@gmail.com, Andrew Morton , Michal Nazarewicz , Minchan Kim , Mel Gorman , Vlastimil Babka , "Kirill A. Shutemov" , Sergey Senozhatsky , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Joonsoo Kim On (02/18/16 09:29), Steven Rostedt wrote: > > diff --git a/include/linux/page_ref.h b/include/linux/page_ref.h > > index 534249c..fd6d9a5 100644 > > --- a/include/linux/page_ref.h > > +++ b/include/linux/page_ref.h > > @@ -1,6 +1,54 @@ > > #include > > #include > > #include > > +#include > > + > > +extern struct tracepoint __tracepoint_page_ref_set; > > +extern struct tracepoint __tracepoint_page_ref_mod; > > +extern struct tracepoint __tracepoint_page_ref_mod_and_test; > > +extern struct tracepoint __tracepoint_page_ref_mod_and_return; > > +extern struct tracepoint __tracepoint_page_ref_mod_unless; > > +extern struct tracepoint __tracepoint_page_ref_freeze; > > +extern struct tracepoint __tracepoint_page_ref_unfreeze; > > + > > +#ifdef CONFIG_DEBUG_PAGE_REF > > Please add a comment here. Something to the effect of: > > /* > * Ideally we would want to use the trace__enabled() helper > * functions. But due to include header file issues, that is not > * feasible. Instead we have to open code the static key functions. > * > * See trace_##name##_enabled(void) in include/linux/tracepoint.h > */ > not sure if it's worth mentioning in the comment, but the other concern here is the performance impact of an extra function call, I believe. otherwise, Joonsoo would just do: in include/linux/page_ref.h static inline void set_page_count(struct page *page, int v) { atomic_set(&page->_count, v); __page_ref_set(page, v); } ... and in mm/debug_page_ref.c void __page_ref_set(struct page *page, int v) { if (trace_page_ref_set_enabled()) trace_page_ref_set(page, v); } EXPORT_SYMBOL(__page_ref_set); EXPORT_TRACEPOINT_SYMBOL(page_ref_set); ... -ss -- 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