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Date:   Wed, 29 Mar 2023 22:11:24 +0530
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Subject: Re: v4: Re: [PATCH v7 00/15] coresight: Add new API to allocate trace
 source ID values
Content-Language: en-US
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mike Leach <mike.leach@linaro.org>, mathieu.poirier@linaro.org,
        peterz@infradead.org, mingo@redhat.com,
        linux-perf-users@vger.kernel.org, leo.yan@linaro.org,
        quic_jinlmao@quicinc.com, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, James Clark <james.clark@arm.com>
References: <20230116124928.5440-1-mike.leach@linaro.org>
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 <2864f28e-dd2f-5a9c-922f-5c044a864beb@arm.com>
 <e3df35fe-a00d-69ec-32ee-53c949909cab@arm.com>
 <6a71acac-c478-6e5d-3165-4ba9526614db@arm.com>
 <5556dc65-79ef-e8d2-e5b4-046594af78ea@os.amperecomputing.com>
 <ZCQ65pLbikC83Jqf@kernel.org>
From:   Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
In-Reply-To: <ZCQ65pLbikC83Jqf@kernel.org>
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On 29-03-2023 06:49 pm, Arnaldo Carvalho de Melo wrote:
> Em Wed, Mar 29, 2023 at 09:44:47AM +0530, Ganapatrao Kulkarni escreveu:
>> Hi Mike,
>>
>> On 27-02-2023 03:56 pm, Suzuki K Poulose wrote:
>>> Mike,
>>>
>>> Please could you send all the perf tool related patches as a seperate
>>> series, with all the tags to Arnaldo directly at -rc1.
>>>
>>> Please add a cover letter explaining that the kernel changes are
>>> available upstream.
>>
>> Looks like, Perf tool patches corresponding to dynamic trace id are not yet
>> merged in to perf-tools-next.
>>
>> Without these patches, the mainline perf tool breaks for the coresight for
>> higher cores.
> 
> I'm pushing what I have to tmp.perf-tools-next while this + other
> changes goes thru my container set build tests.

Thanks Arnaldo!
> 
> - Arnaldo
>   
>>>
>>> Kind regards
>>> Suzuki
>>>
>>> On 20/02/2023 16:24, Suzuki K Poulose wrote:
>>>> Arnaldo
>>>>
>>>> Gentle ping
>>>>
>>>>
>>>> On 31/01/2023 11:49, Suzuki K Poulose wrote:
>>>>> Hi Arnaldo
>>>>>
>>>>> On 24/01/2023 11:36, Suzuki K Poulose wrote:
>>>>>> Hi Arnaldo
>>>>>>
>>>>>> Gentle ping.
>>>>>>
>>>>>> On 19/01/2023 12:00, Suzuki K Poulose wrote:
>>>>>>> Hi Arnaldo,
>>>>>>>
>>>>>>> On 16/01/2023 12:49, Mike Leach wrote:
>>>>>>>> The current method for allocating trace source ID
>>>>>>>> values to sources is
>>>>>>>> to use a fixed algorithm for CPU based sources of
>>>>>>>> (cpu_num * 2 + 0x10).
>>>>>>>> The STM is allocated ID 0x1.
>>>>>>>>
>>>>>>>> This fixed algorithm is used in both the CoreSight
>>>>>>>> driver code, and by
>>>>>>>> perf when writing the trace metadata in the AUXTRACE_INFO record.
>>>>>>>>
>>>>>>>> The method needs replacing as currently:-
>>>>>>>> 1. It is inefficient in using available IDs.
>>>>>>>> 2. Does not scale to larger systems with many cores and the algorithm
>>>>>>>> has no limits so will generate invalid trace IDs for cpu number > 44.
>>>>>>>>
>>>>>>>> Additionally requirements to allocate additional system IDs on some
>>>>>>>> systems have been seen.
>>>>>>>>
>>>>>>>> This patch set  introduces an API that allows the
>>>>>>>> allocation of trace IDs
>>>>>>>> in a dynamic manner.
>>>>>>>>
>>>>>>>> Architecturally reserved IDs are never allocated, and the system is
>>>>>>>> limited to allocating only valid IDs.
>>>>>>>>
>>>>>>>> Each of the current trace sources ETM3.x, ETM4.x and
>>>>>>>> STM is updated to use
>>>>>>>> the new API.
>>>>>>>>
>>>>>>>> For the ETMx.x devices IDs are allocated on certain events
>>>>>>>> a) When using sysfs, an ID will be allocated on
>>>>>>>> hardware enable, or a read of
>>>>>>>> sysfs TRCTRACEID register and freed when the sysfs reset is written.
>>>>>>>>
>>>>>>>> b) When using perf, ID is allocated on during setup
>>>>>>>> AUX event, and freed on
>>>>>>>> event free. IDs are communicated using the AUX_OUTPUT_HW_ID packet.
>>>>>>>> The ID allocator is notified when perf sessions start and stop
>>>>>>>> so CPU based IDs are kept constant throughout any perf session.
>>>>>>>>
>>>>>>>>
>>>>>>>> Note: This patchset breaks some backward
>>>>>>>> compatibility for perf record and
>>>>>>>> perf report.
>>>>>>>>
>>>>>>>> The version of the AUXTRACE_INFO has been updated to
>>>>>>>> reflect the fact that
>>>>>>>> the trace source IDs are generated differently. This will
>>>>>>>> mean older versions of perf report cannot decode the newer file.
>>>>>>>>
>>>>>>>> Appies to coresight/next
>>>>>>>>
>>>>>>
>>>>>> ...
>>>>>>
>>>>>>>> Mike Leach (15):
>>>>>>>>     coresight: trace-id: Add API to dynamically assign Trace ID values
>>>>>>>>     coresight: Remove obsolete Trace ID unniqueness checks
>>>>>>>>     coresight: perf: traceid: Add perf ID allocation and notifiers
>>>>>>>>     coresight: stm: Update STM driver to use Trace ID API
>>>>>>>>     coresight: etm4x: Update ETM4 driver to use Trace ID API
>>>>>>>>     coresight: etm3x: Update ETM3 driver to use Trace ID API
>>>>>>>>     coresight: etmX.X: stm: Remove trace_id() callback
>>>>>>>>     coresight: trace id: Remove legacy get trace ID function.
>>>>>>>>     perf: cs-etm: Move mapping of Trace ID and cpu
>>>>>>>> into helper function
>>>>>>>>     perf: cs-etm: Update record event to use new Trace ID protocol
>>>>>>>>     kernel: events: Export perf_report_aux_output_id()
>>>>>>>>     perf: cs-etm: Handle PERF_RECORD_AUX_OUTPUT_HW_ID packet
>>>>>>>>     coresight: events: PERF_RECORD_AUX_OUTPUT_HW_ID used for Trace ID
>>>>>>>>     coresight: trace-id: Add debug & test macros to
>>>>>>>> Trace ID allocation
>>>>>>>>     coresight: etm3x: docs: Alter sysfs documentation
>>>>>>>> for trace id updates
>>>>>>>
>>>>>>> I have pushed the kernel patches on this series to
>>>>>>> coresight tree next[0].
>>>>>>>
>>>>>>> I will be sending them out to Greg for v6.3. Please
>>>>>>> could you queue the
>>>>>>> perf tool changes in the series ? i.e., Patches 9,10 and 12.
>>>>>>>
>>>>>>>
>>>>>>> [0] https://git.kernel.org/pub/scm/linux/kernel/git/coresight/linux.git/log/?h=next
>>>>>>>
>>>>>>
>>>>>> Please could you pick up the perf tool changes above ?
>>>>>
>>>>> Please could you confirm if you are able to queue the perf tool
>>>>> changes ? Or would you like me route it via coresight tree ?
>>>>>
>>>>> Kind regards
>>>>> Suzuki
>>>>>
>>>>
>>>>
>>>> Suzuki
>>>>
>>>
>>
>> Thanks,
>> Ganapat
>>
>

Thanks,
Ganapat