linux-kernel - Re: [PATCH 2/2] mm/page_ref: add tracepoint to track down page reference manipulation

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Message-ID: <20160219021522.GA11625@swordfish>
Date:	Fri, 19 Feb 2016 11:15:22 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Joonsoo Kim <js1304@...il.com>
Cc:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Nazarewicz <mina86@...a86.com>,
	Minchan Kim <minchan@...nel.org>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Vlastimil Babka <vbabka@...e.cz>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Linux Memory Management List <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-api@...r.kernel.org,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH 2/2] mm/page_ref: add tracepoint to track down page
 reference manipulation

On (02/19/16 10:39), Joonsoo Kim wrote:
[..]
> > 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:
> 
> It's very natural thing so I'm not sure it is worth mentioning.

agree.

> > 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);
> 
> It is what I did in v1.

ah... indeed. well, "That was a year ago, how am I suppose to remember"

	-ss