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Message-ID: <cb7c6deb-e4a1-95fa-b0d2-e4405f644e63@arm.com>
Date: Mon, 1 Feb 2021 19:40:45 +0200
From: James Clark <james.clark@....com>
To: Leo Yan <leo.yan@...aro.org>
Cc: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
John Garry <john.garry@...wei.com>,
Will Deacon <will@...nel.org>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Al Grant <al.grant@....com>,
Andre Przywara <andre.przywara@....com>,
Wei Li <liwei391@...wei.com>,
Tan Xiaojun <tanxiaojun@...wei.com>,
Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 8/8] perf arm-spe: Set thread TID
On 31/01/2021 14:01, Leo Yan wrote:
> Option 1: by merging patches 07/08 and 08/08, we can firstly support PID
> tracing for root namespace, and later we can extend to support PID
> tracing in container (and in VMs).
>
> Option 2: we can use the software method to establish PID for SPE
> trace, which can base on kernel's events PERF_RECORD_SWITCH /
> PERF_RECORD_SWITCH_CPU_WIDE and check context switch ip.
>
> To be honest, I am a bit concern for option 1 for later might
> introduce regression when later support PID for containers (and VMs).
> If you have a plan for option 1, I think it's good to record current
> limitation and the plan for next step in the commit log, so we can merge
> this patch at this time and later extend for containers.
>
> Otherwise, we need to consider how to implement the PID tracing with
> option 2. If it is the case, we should firstly only merge patches
> 01 ~ 06 for data source enabling. How about you think for this?
In my opinion we should do option 1 and use what is there at the moment. That
gets users 90% of the functionality right now.
I plan to look at option 2 at some point, and it can always be added on top of
option 1 or replace what is there. But I don't know when I would get to it or
how long it will take.
James
>
>> Signed-off-by: Leo Yan <leo.yan@...aro.org>
>> Signed-off-by: James Clark <james.clark@....com>
>
> Besides for techinical question, you could add your "Co-developed-by"
> tags for patches 06, 07, 08/08, which you have took time to refin them.
>
> Thanks you for kindly efforts.
>
> [1] https://lore.kernel.org/patchwork/patch/1353286/
>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
>> Cc: Jiri Olsa <jolsa@...hat.com>
>> Cc: Namhyung Kim <namhyung@...nel.org>
>> Cc: John Garry <john.garry@...wei.com>
>> Cc: Will Deacon <will@...nel.org>
>> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
>> Cc: Al Grant <al.grant@....com>
>> Cc: Andre Przywara <andre.przywara@....com>
>> Cc: Wei Li <liwei391@...wei.com>
>> Cc: Tan Xiaojun <tanxiaojun@...wei.com>
>> Cc: Adrian Hunter <adrian.hunter@...el.com>
>> ---
>> tools/perf/util/arm-spe.c | 75 ++++++++++++++++++++++++++-------------
>> 1 file changed, 50 insertions(+), 25 deletions(-)
>>
>> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
>> index 27a0b9dfe22d..9828fad7e516 100644
>> --- a/tools/perf/util/arm-spe.c
>> +++ b/tools/perf/util/arm-spe.c
>> @@ -223,6 +223,46 @@ static inline u8 arm_spe_cpumode(struct arm_spe *spe, u64 ip)
>> PERF_RECORD_MISC_USER;
>> }
>>
>> +static void arm_spe_set_pid_tid_cpu(struct arm_spe *spe,
>> + struct auxtrace_queue *queue)
>> +{
>> + struct arm_spe_queue *speq = queue->priv;
>> + pid_t tid;
>> +
>> + tid = machine__get_current_tid(spe->machine, speq->cpu);
>> + if (tid != -1) {
>> + speq->tid = tid;
>> + thread__zput(speq->thread);
>> + } else
>> + speq->tid = queue->tid;
>> +
>> + if ((!speq->thread) && (speq->tid != -1)) {
>> + speq->thread = machine__find_thread(spe->machine, -1,
>> + speq->tid);
>> + }
>> +
>> + if (speq->thread) {
>> + speq->pid = speq->thread->pid_;
>> + if (queue->cpu == -1)
>> + speq->cpu = speq->thread->cpu;
>> + }
>> +}
>> +
>> +static int arm_spe_set_tid(struct arm_spe_queue *speq, pid_t tid)
>> +{
>> + int err;
>> + struct arm_spe *spe = speq->spe;
>> + struct auxtrace_queue *queue;
>> +
>> + err = machine__set_current_tid(spe->machine, speq->cpu, tid, tid);
>> + if (err)
>> + return err;
>> +
>> + queue = &speq->spe->queues.queue_array[speq->queue_nr];
>> + arm_spe_set_pid_tid_cpu(speq->spe, queue);
>> + return 0;
>> +}
>> +
>> static void arm_spe_prep_sample(struct arm_spe *spe,
>> struct arm_spe_queue *speq,
>> union perf_event *event,
>> @@ -431,6 +471,7 @@ static int arm_spe_sample(struct arm_spe_queue *speq)
>> static int arm_spe_run_decoder(struct arm_spe_queue *speq, u64 *timestamp)
>> {
>> struct arm_spe *spe = speq->spe;
>> + const struct arm_spe_record *record;
>> int ret;
>>
>> if (!spe->kernel_start)
>> @@ -450,6 +491,11 @@ static int arm_spe_run_decoder(struct arm_spe_queue *speq, u64 *timestamp)
>> if (ret < 0)
>> continue;
>>
>> + record = &speq->decoder->record;
>> + ret = arm_spe_set_tid(speq, record->context_id);
>> + if (ret)
>> + return ret;
>> +
>> ret = arm_spe_sample(speq);
>> if (ret)
>> return ret;
>> @@ -500,6 +546,10 @@ static int arm_spe__setup_queue(struct arm_spe *spe,
>>
>> record = &speq->decoder->record;
>>
>> + ret = arm_spe_set_tid(speq, record->context_id);
>> + if (ret)
>> + return ret;
>> +
>> speq->timestamp = record->timestamp;
>> ret = auxtrace_heap__add(&spe->heap, queue_nr, speq->timestamp);
>> if (ret)
>> @@ -552,31 +602,6 @@ static bool arm_spe__is_timeless_decoding(struct arm_spe *spe)
>> return timeless_decoding;
>> }
>>
>> -static void arm_spe_set_pid_tid_cpu(struct arm_spe *spe,
>> - struct auxtrace_queue *queue)
>> -{
>> - struct arm_spe_queue *speq = queue->priv;
>> - pid_t tid;
>> -
>> - tid = machine__get_current_tid(spe->machine, speq->cpu);
>> - if (tid != -1) {
>> - speq->tid = tid;
>> - thread__zput(speq->thread);
>> - } else
>> - speq->tid = queue->tid;
>> -
>> - if ((!speq->thread) && (speq->tid != -1)) {
>> - speq->thread = machine__find_thread(spe->machine, -1,
>> - speq->tid);
>> - }
>> -
>> - if (speq->thread) {
>> - speq->pid = speq->thread->pid_;
>> - if (queue->cpu == -1)
>> - speq->cpu = speq->thread->cpu;
>> - }
>> -}
>> -
>> static int arm_spe_process_queues(struct arm_spe *spe, u64 timestamp)
>> {
>> unsigned int queue_nr;
>> --
>> 2.28.0
>>
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