netdev - Re: [PATCH v4 bpf-next 1/4] bpftool: introduce "prog profile" command

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Message-ID: <5BAF92A4-6CE4-4578-8481-96678D4E1201@fb.com>
Date:   Thu, 5 Mar 2020 20:03:02 +0000
From:   Song Liu <songliubraving@...com>
To:     Jiri Olsa <jolsa@...hat.com>
CC:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "Quentin Monnet" <quentin@...valent.com>,
        Kernel Team <Kernel-team@...com>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "arnaldo.melo@...il.com" <arnaldo.melo@...il.com>,
        "jolsa@...nel.org" <jolsa@...nel.org>
Subject: Re: [PATCH v4 bpf-next 1/4] bpftool: introduce "prog profile" command



> On Mar 4, 2020, at 12:38 PM, Jiri Olsa <jolsa@...hat.com> wrote:
> 
> On Wed, Mar 04, 2020 at 10:07:07AM -0800, Song Liu wrote:
> 
> SNIP
> 
>> +
>> +#include "profiler.skel.h"
>> +
>> +#define SAMPLE_PERIOD  0x7fffffffffffffffULL
>> +struct profile_metric {
>> +	const char *name;
>> +	struct bpf_perf_event_value val;
>> +	struct perf_event_attr attr;
>> +	bool selected;
>> +
>> +	/* calculate ratios like instructions per cycle */
>> +	const int ratio_metric; /* 0 for N/A, 1 for index 0 (cycles) */
>> +	const char *ratio_desc;
>> +	const float ratio_mul;
>> +} metrics[] = {
>> +	{
>> +		.name = "cycles",
>> +		.attr = {
>> +			.sample_period = SAMPLE_PERIOD,
> 
> I don't think you need to set sample_period for counting.. why?
> 
>> +			.type = PERF_TYPE_HARDWARE,
>> +			.config = PERF_COUNT_HW_CPU_CYCLES,
> 
> you could also add .exclude_user = 1

Fixed this in v5. Thanks!
Song