> On Apr 28, 2020, at 9:57 PM, Alexei Starovoitov
> <alexei.starovoi...@gmail.com> wrote:
>
> On Tue, Apr 28, 2020 at 08:58:41PM -0700, Song Liu wrote:
>> +
>> + skel = test_enable_stats__open_and_load();
>> + if (CHECK(!skel, "skel_open_and_load", "skeleton open/load failed\n"))
>> + return;
>> +
>> + stats_fd = bpf_enable_stats(BPF_STATS_RUNTIME_CNT);
>
> Just realized that the name is wrong.
> The stats are enabling run_cnt and run_time_ns.
> runtime_cnt sounds like 'snark' from 'The Hunting of the Snark' :)
> May be BPF_STATS_RUN_TIME ?
Will fix.
[...]
>> +
>> + CHECK(info.run_cnt != count, "check_run_cnt_valid",
>> + "invalid run_cnt stats\n");
>
> what happens if there are other syscalls during for(i<100) loop?
> The count will still match, right?
> Then why 100 ? and why usleep() at all?
> test_enable_stats__attach() will generate at least one syscall.
We don't really need usleep. I was thinking if it matches after
many calls it really matches... I will remove it.
>
>> +
>> +cleanup:
>> + test_enable_stats__destroy(skel);
>> + close(stats_fd);
>
> May be close(stats_fd) first.
> Then test_enable_stats__attach(skel); again.
> Generate few more syscalls and check that 'count' incrementing,
> but info.run_cnt doesnt ?
> That check assumes that sysctl is off. Overkill?
I thought about this. However, close(stats_fd) cannot guarantee
the stats is not enabled by other fd or the sysctl. I think this
will generate noise on specific systems.
Thanks,
Song
