linux-kernel - Re: [PATCH v5 01/17] perf: Add SNOOP

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Date:   Wed, 20 Jul 2022 15:46:49 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Leo Yan <leo.yan@...aro.org>, Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        James Clark <james.clark@....com>,
        German Gomez <german.gomez@....com>,
        Ali Saidi <alisaidi@...zon.com>, Joe Mario <jmario@...hat.com>,
        Adam Li <adam.li@...erecomputing.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Kajol Jain <kjain@...ux.ibm.com>
Subject: Re: [PATCH v5 01/17] perf: Add SNOOP_PEER flag to perf mem data
 struct

Em Wed, Jul 20, 2022 at 03:45:51PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Sat, Jun 04, 2022 at 12:28:04PM +0800, Leo Yan escreveu:
> > From: Ali Saidi <alisaidi@...zon.com>
> > 
> > Add a flag to the perf mem data struct to signal that a request caused a
> > cache-to-cache transfer of a line from a peer of the requestor and
> > wasn't sourced from a lower cache level.  The line being moved from one
> > peer cache to another has latency and performance implications. On Arm64
> > Neoverse systems the data source can indicate a cache-to-cache transfer
> > but not if the line is dirty or clean, so instead of overloading HITM
> > define a new flag that indicates this type of transfer.
> > 
> > Signed-off-by: Ali Saidi <alisaidi@...zon.com>
> > Reviewed-by: Leo Yan <leo.yan@...aro.org>
> > Reviewed-by: Kajol Jain<kjain@...ux.ibm.com>
> 
> Hey, any knews about this going upstream? PeterZ?

Just took a look and it isn't in tip/master.

- Arnaldo
 
> > ---
> >  include/uapi/linux/perf_event.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> > index d37629dbad72..7b88bfd097dc 100644
> > --- a/include/uapi/linux/perf_event.h
> > +++ b/include/uapi/linux/perf_event.h
> > @@ -1310,7 +1310,7 @@ union perf_mem_data_src {
> >  #define PERF_MEM_SNOOP_SHIFT	19
> >  
> >  #define PERF_MEM_SNOOPX_FWD	0x01 /* forward */
> > -/* 1 free */
> > +#define PERF_MEM_SNOOPX_PEER	0x02 /* xfer from peer */
> >  #define PERF_MEM_SNOOPX_SHIFT  38
> >  
> >  /* locked instruction */
> > -- 
> > 2.25.1
> 
> -- 
> 
> - Arnaldo

-- 

- Arnaldo