linux-kernel - Re: [RFC v3 01/17] perf kwork: New tool

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Date:   Thu, 28 Jul 2022 19:48:53 +0800
From:   Yang Jihong <yangjihong1@...wei.com>
To:     Namhyung Kim <namhyung@...nel.org>
CC:     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@...nel.org>, "Paul Clarke" <pc@...ibm.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>
Subject: Re: [RFC v3 01/17] perf kwork: New tool

Hello Namhyung,

On 2022/7/28 7:33, Namhyung Kim wrote:
> Hello,
> 
> On Fri, Jul 8, 2022 at 6:53 PM Yang Jihong <yangjihong1@...wei.com> wrote:
>>
>> The perf-kwork tool is used to trace time properties of kernel work
>> (such as irq, softirq, and workqueue), including runtime, latency,
>> and timehist, using the infrastructure in the perf tools to allow
>> tracing extra targets.
>>
>> This is the first commit to reuse perf_record framework code to
>> implement a simple record function, kwork is not supported currently.
>>
>> Test cases:
>>
>>    # perf
>>
>>     usage: perf [--version] [--help] [OPTIONS] COMMAND [ARGS]
>>
>>     The most commonly used perf commands are:
>>    <SNIP>
>>       iostat          Show I/O performance metrics
>>       kallsyms        Searches running kernel for symbols
>>       kmem            Tool to trace/measure kernel memory properties
>>       kvm             Tool to trace/measure kvm guest os
>>       kwork           Tool to trace/measure kernel work properties (latencies)
>>       list            List all symbolic event types
>>       lock            Analyze lock events
>>       mem             Profile memory accesses
>>       record          Run a command and record its profile into perf.data
>>    <SNIP>
>>     See 'perf help COMMAND' for more information on a specific command.
>>
>>    # perf kwork
>>
>>     Usage: perf kwork [<options>] {record}
>>
>>        -D, --dump-raw-trace  dump raw trace in ASCII
>>        -f, --force           don't complain, do it
>>        -k, --kwork <kwork>   list of kwork to profile
>>        -v, --verbose         be more verbose (show symbol address, etc)
>>
>>    # perf kwork record -- sleep 1
>>    [ perf record: Woken up 0 times to write data ]
>>    [ perf record: Captured and wrote 1.787 MB perf.data ]
>>
>> Signed-off-by: Yang Jihong <yangjihong1@...wei.com>
>> ---
> [SNIP]
>> +
>> +static int perf_kwork__record(struct perf_kwork *kwork,
>> +                             int argc, const char **argv)
>> +{
>> +       const char **rec_argv;
>> +       unsigned int rec_argc, i, j;
>> +       struct kwork_class *class;
>> +
>> +       const char *const record_args[] = {
>> +               "record",
>> +               "-a",
>> +               "-R",
>> +               "-m", "1024",
>> +               "-c", "1",
> 
> Please consider adding '--synth task' to skip costly synthesis
> if you don't need user space symbols.
> 
Yes, we don't need user space symbols now, I'll add this option in next 
fix patch,thanks for your suggestion.

Regards,
Jihong
> .
>