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

[Vlastimil Babka]

On 08/31/2015 04:58 PM, Steven Rostedt wrote:
> On Thu, 27 Aug 2015 17:24:03 +0200
> Vlastimil Babka <vbabka@xxxxxxx> 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@xxxxxxx>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: Mel Gorman <mgorman@xxxxxxx>
> > Cc: David Rientjes <rientjes@xxxxxxxxxx>
> > ---
> >   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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