linux-kernel - Re: [PATCH 2/3] mm, compaction: export tracepoints zone names to userspace

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Date:	Mon, 31 Aug 2015 17:02:38 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Ingo Molnar <mingo@...hat.com>, Mel Gorman <mgorman@...e.de>,
	David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH 2/3] mm, compaction: export tracepoints zone names to
 userspace

On 08/31/2015 04:58 PM, Steven Rostedt wrote:
> On Thu, 27 Aug 2015 17:24:03 +0200
> Vlastimil Babka <vbabka@...e.cz> wrote:
>
>> Some compaction tracepoints use zone->name to print which zone is being
>> compacted. This works for in-kernel printing, but not userspace trace printing
>> of raw captured trace such as via trace-cmd report.
>>
>> This patch uses zone_idx() instead of zone->name as the raw value, and when
>> printing, converts the zone_type to string using the appropriate EM() macros
>> and some ugly tricks to overcome the problem that half the values depend on
>> CONFIG_ options and one does not simply use #ifdef inside of #define.
>>
>> trace-cmd output before:
>> transhuge-stres-4235  [000]   453.149280: mm_compaction_finished: node=0
>> zone=ffffffff81815d7a order=9 ret=partial
>>
>> after:
>> transhuge-stres-4235  [000]   453.149280: mm_compaction_finished: node=0
>> zone=Normal   order=9 ret=partial
>>
>> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
>> Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
>> Cc: Steven Rostedt <rostedt@...dmis.org>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Mel Gorman <mgorman@...e.de>
>> Cc: David Rientjes <rientjes@...gle.com>
>> ---
>>   include/trace/events/compaction.h | 38 ++++++++++++++++++++++++++++++++------
>>   1 file changed, 32 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/trace/events/compaction.h b/include/trace/events/compaction.h
>> index 1275a55..8daa8fa 100644
>> --- a/include/trace/events/compaction.h
>> +++ b/include/trace/events/compaction.h
>> @@ -18,6 +18,31 @@
>>   	EM( COMPACT_NO_SUITABLE_PAGE,	"no_suitable_page")	\
>>   	EMe(COMPACT_NOT_SUITABLE_ZONE,	"not_suitable_zone")
>>
>> +#ifdef CONFIG_ZONE_DMA
>> +#define IFDEF_ZONE_DMA(X) X
>> +#else
>> +#define IFDEF_ZONE_DMA(X)
>> +#endif
>> +
>> +#ifdef CONFIG_ZONE_DMA32
>> +#define IFDEF_ZONE_DMA32(X) X
>> +#else
>> +#define IFDEF_ZONE_DMA32(X)
>> +#endif
>> +
>> +#ifdef CONFIG_ZONE_HIGHMEM_
>> +#define IFDEF_ZONE_HIGHMEM(X) X
>> +#else
>> +#define IFDEF_ZONE_HIGHMEM(X)
>> +#endif
>> +
>> +#define ZONE_TYPE						\
>> +	IFDEF_ZONE_DMA(		EM (ZONE_DMA,	 "DMA"))	\
>> +	IFDEF_ZONE_DMA32(	EM (ZONE_DMA32,	 "DMA32"))	\
>> +				EM (ZONE_NORMAL, "Normal")	\
>> +	IFDEF_ZONE_HIGHMEM(	EM (ZONE_HIGHMEM,"HighMem"))	\
>> +				EMe(ZONE_MOVABLE,"Movable")
>> +
>
> Hmm, have you tried to compile this with CONFIG_ZONE_HIGHMEM disabled,
> and CONFIG_ZONE_DMA and/or CONFIG_ZONE_DMA32 enabled?

Yep, that's standard x86_64 situation (highmem disabled, dma+dma32 enabled).

> The EMe() macro must come last, as it doesn't have the ending comma and
> the __print_symbolic() can fail to compile due to it.

Thanks to ZONE_MOVABLE being unconditional, EMe(ZONE_MOVABLE...) is 
always last. Otherwise the macros would get even more ugly...

> -- Steve
>
>
>>   /*
>>    * First define the enums in the above macros to be exported to userspace
>>    * via TRACE_DEFINE_ENUM().
>> @@ -28,6 +53,7 @@

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