linux-kernel - Re: [PATCH] perf vendor events arm64: Enable JSON events for ThunderX2 B0

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Message-ID: <2a84ec0e-dc8c-7e2e-64e5-4ea48ba6da49@redhat.com>
Date:   Thu, 15 Mar 2018 11:53:18 -0400
From:   William Cohen <wcohen@...hat.com>
To:     Ganapatrao Kulkarni <gklkml16@...il.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>, mark.rutland@....com,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <Will.Deacon@....com>,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Robert Richter <Robert.Richter@...ium.com>,
        Ingo Molnar <mingo@...hat.com>, jnair@...iumnetworks.com,
        Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>,
        Jiri Olsa <jolsa@...hat.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] perf vendor events arm64: Enable JSON events for
 ThunderX2 B0

On 03/07/2018 11:14 PM, Ganapatrao Kulkarni wrote:
> On Thu, Mar 8, 2018 at 12:01 AM, William Cohen <wcohen@...hat.com> wrote:
>> On 03/07/2018 12:35 PM, Ganapatrao Kulkarni wrote:
>>> Hi Will Cohen,
>>>
>>> On Wed, Mar 7, 2018 at 8:08 PM, Arnaldo Carvalho de Melo
>>> <acme@...nel.org> wrote:
>>>> Em Wed, Mar 07, 2018 at 09:32:05AM -0500, William Cohen escreveu:
>>>>> On 03/07/2018 06:08 AM, Ganapatrao Kulkarni wrote:
>>>>>> There is MIDR change on ThunderX2 B0, adding an entry to mapfile
>>>>>> to enable JSON events for B0.
>>>>>>
>>>>>> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>
>>>>
>>>> Ganapatrao, can you please take this in consideration and if agreeing
>>>> send a v2 patch?
>>>>
>>>> With that I can add an Acked-by: wcohen, Right?
>>>>
>>>> - Arnaldo
>>>>>> ---
>>>>>>  tools/perf/pmu-events/arch/arm64/mapfile.csv | 1 +
>>>>>>  1 file changed, 1 insertion(+)
>>>>>>
>>>>>> diff --git a/tools/perf/pmu-events/arch/arm64/mapfile.csv b/tools/perf/pmu-events/arch/arm64/mapfile.csv
>>>>>> index e61c9ca..93c5d14 100644
>>>>>> --- a/tools/perf/pmu-events/arch/arm64/mapfile.csv
>>>>>> +++ b/tools/perf/pmu-events/arch/arm64/mapfile.csv
>>>>>> @@ -13,4 +13,5 @@
>>>>>>  #
>>>>>>  #Family-model,Version,Filename,EventType
>>>>>>  0x00000000420f5160,v1,cavium,core
>>>>>> +0x00000000430f0af0,v1,cavium,core
>>>>>>  0x00000000410fd03[[:xdigit:]],v1,cortex-a53,core
>>>>>>
>>>>>
>>>>> Hi,
>>>>> Like the cortex-a53 the last digit '0' of the match for the MIDR should be replaced with [[:xdigit:]] to allow for possible future revisions of chip:
>>>
>>> for arm64 implementation,  bits 3:0(Revision) and bits 23:20(Variant)
>>> are ignored/dont-care.
>>
>> Thanks for pointing that out.  See the code masking out those bits in linux/toos/perf/arch/util/header.c. For the ppc64 it just copies the equivalent of the MIDR including the revision bits. Thus, the need for regular expression matching to avoid having to create a new entry for each revision.
> 
> It is same for arm64 too, there is no need to add an entry for every
> revision change,  need to add when part number changes.
> This patch is not intended to add entry for revision change, the fact
> of the matter is that, there  is complete MIDR change (vulcan to
> thunderx2) in B0.
> as per current arm64
> implementation(.tools/perf/arch/arm64/util/header.c), it is not
> required to have any dontcare marking in mapfile for revision/variant
> bits.
> 
> thanks
> Ganapat

Hi Ganapat,

Would it make more sense to pass the MIDR value unmodified and then use regular expressions in mapfile.csv to match the values?  If an event on a particular processor revision is broken or unusable it can be excluded from the list of events with a corrected list of events.  There certainly have been errata listing events that do not work on specific revisions of armv8 processor implementations.

-Will