Re: v4: Re: [PATCH v7 00/15] coresight: Add new API to allocate trace source ID values

From: Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
To: Suzuki K Poulose <suzuki.poulose@arm.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mike Leach <mike.leach@linaro.org>
Cc: 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>
Subject: Re: v4: Re: [PATCH v7 00/15] coresight: Add new API to allocate trace source ID values
Date: Wed, 29 Mar 2023 09:44:47 +0530	[thread overview]
Message-ID: <5556dc65-79ef-e8d2-e5b4-046594af78ea@os.amperecomputing.com> (raw)
In-Reply-To: <6a71acac-c478-6e5d-3165-4ba9526614db@arm.com>

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.

> 
> 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