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Date: Fri, 19 Feb 2016 10:39:10 +0900 From: Joonsoo Kim <js1304@...il.com> To: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com> Cc: 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 2016-02-19 9:34 GMT+09:00 Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>: > 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 <linux/atomic.h> >> > #include <linux/mm_types.h> >> > #include <linux/page-flags.h> >> > +#include <linux/tracepoint-defs.h> >> > + >> > +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_<tracepoint>_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: It's very natural thing so I'm not sure it is worth mentioning. > 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); It is what I did in v1. Thanks.
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