linux-kernel - Re: [PATCH v2] tools/power turbostat: Increase the limit for fd opened

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Date:   Mon, 27 Nov 2023 20:47:55 -0500
From:   Len Brown <lenb@...nel.org>
To:     Wyes Karny <wyes.karny@....com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Doug Smythies <dsmythies@...us.net>
Subject: Re: [PATCH v2] tools/power turbostat: Increase the limit for fd opened

Applied

Thanks Wyes!

On Tue, Oct 3, 2023 at 1:08 AM Wyes Karny <wyes.karny@....com> wrote:
>
> When running turbostat, a system with 512 cpus reaches the limit for
> maximum number of file descriptors that can be opened. To solve this
> problem, the limit is raised to 2^15, which is a large enough number.
>
> Below data is collected from AMD server systems while running turbostat:
>
> |-----------+-------------------------------|
> | # of cpus | # of opened fds for turbostat |
> |-----------+-------------------------------|
> | 128       | 260                           |
> |-----------+-------------------------------|
> | 192       | 388                           |
> |-----------+-------------------------------|
> | 512       | 1028                          |
> |-----------+-------------------------------|
>
> So, the new max limit would be sufficient up to 2^14 cpus (but this
> also depends on how many counters are enabled).
>
> Reviewed-by: Doug Smythies <dsmythies@...us.net>
> Tested-by: Doug Smythies <dsmythies@...us.net>
> Signed-off-by: Wyes Karny <wyes.karny@....com>
> ---
> v1 -> v2:
> - Take care of already higher rlim_max, rlim_curr
> - Minor tweak in commit text
>
>  tools/power/x86/turbostat/turbostat.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
> index 9a10512e3407..1563a0ae7e4c 100644
> --- a/tools/power/x86/turbostat/turbostat.c
> +++ b/tools/power/x86/turbostat/turbostat.c
> @@ -53,6 +53,8 @@
>  #define        NAME_BYTES 20
>  #define PATH_BYTES 128
>
> +#define MAX_NOFILE 0x8000
> +
>  enum counter_scope { SCOPE_CPU, SCOPE_CORE, SCOPE_PACKAGE };
>  enum counter_type { COUNTER_ITEMS, COUNTER_CYCLES, COUNTER_SECONDS, COUNTER_USEC };
>  enum counter_format { FORMAT_RAW, FORMAT_DELTA, FORMAT_PERCENT };
> @@ -6717,6 +6719,22 @@ void cmdline(int argc, char **argv)
>         }
>  }
>
> +void set_rlimit(void)
> +{
> +       struct rlimit limit;
> +
> +       if (getrlimit(RLIMIT_NOFILE, &limit) < 0)
> +               err(1, "Failed to get rlimit");
> +
> +       if (limit.rlim_max < MAX_NOFILE)
> +               limit.rlim_max = MAX_NOFILE;
> +       if (limit.rlim_cur < MAX_NOFILE)
> +               limit.rlim_cur = MAX_NOFILE;
> +
> +       if (setrlimit(RLIMIT_NOFILE, &limit) < 0)
> +               err(1, "Failed to set rlimit");
> +}
> +
>  int main(int argc, char **argv)
>  {
>         outf = stderr;
> @@ -6729,6 +6747,9 @@ int main(int argc, char **argv)
>
>         probe_sysfs();
>
> +       if (!getuid())
> +               set_rlimit();
> +
>         turbostat_init();
>
>         msr_sum_record();
> --
> 2.34.1
>


-- 
Len Brown, Intel