linux-kernel - Re: [PATCH 1/2] perf tools: add 'perf irq' to measure the hardware interrupts

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Date:   Thu, 14 Jan 2021 15:29:52 +0800
From:   Bixuan Cui <cuibixuan@...wei.com>
To:     Alexei Budankov <abudankov@...wei.com>, <peterz@...radead.org>,
        <mingo@...hat.com>, <acme@...nel.org>, <mark.rutland@....com>,
        <alexander.shishkin@...ux.intel.com>, <jolsa@...hat.com>,
        <namhyung@...nel.org>, <linux-kernel@...r.kernel.org>
CC:     <john.wanghui@...wei.com>
Subject: Re: [PATCH 1/2] perf tools: add 'perf irq' to measure the hardware
 interrupts



On 2021/1/13 3:50, Alexei Budankov wrote:
> Hi Bixuan,
> 
> On 12.01.2021 15:55, Bixuan Cui wrote:
>> Add 'perf irq' to trace/measure the hardware interrupts.
>>
>> Now three functions are provided:
>>   1. 'perf irq record <command>' to record the irq handler events.
>>   2. 'perf irq script' to see a detailed trace of the workload that
>>    was recorded.
>>   3. 'perf irq timeconsume' to calculate the time consumed by each
>>    hardware interrupt processing function.
>>
>> Signed-off-by: Bixuan Cui <cuibixuan@...wei.com>
> Thanks for the patches. There is still something that could be improved.
> 
>> ---
>>  tools/perf/Build         |   1 +
>>  tools/perf/builtin-irq.c | 288 +++++++++++++++++++++++++++++++++++++++
>>  tools/perf/builtin.h     |   1 +
>>  tools/perf/perf.c        |   1 +
>>  4 files changed, 291 insertions(+)
>>  create mode 100644 tools/perf/builtin-irq.c
>>
> <SNIP>
> 
>> +
>> +static int __cmd_record(int argc, const char **argv)
>> +{
>> +	unsigned int rec_argc, i, j;
>> +	const char **rec_argv;
>> +	const char * const record_args[] = {
>> +		"record",
>> +		"-a",
> I see it works also like this:
> 
> sudo perf record -p PID -c 1 -e irq:irq_handler_entry,irq:irq_handler_exit
> sudo perf record -R -c 1 -e irq:irq_handler_entry,irq:irq_handler_exit -- find /
> 
> This -a option jointly with -p option could be made configurable from
> the command line for perf irq mode.
That's true. We can add a series of commands for 'perf irq',such as record, script and report.
So I kept the 'perf irq record'.

> 
>> +		"-R",
>> +		"-m", "1024",
> Do you see data losses with default buffer size of 512KB
> when capturing trace in your specific use case?
> 
> If not then this -m could be avoided or made configurable
> if you still need it.
Thank you for your advice, I will delete it.