Hi, Sergey!

Thanks for the patch!

LGTM after submitting a new issue about investigating CLOCK_REALTIME 
drawbacks

Sergey

On 12/26/25 12:17, Sergey Kaplun wrote:
> This module contains 2 functions:
> - `realtime()` -- returns the time represented by the wall clock.
> - `process_cputime()` -- measures the CPU time instead of elapsed time.
>
> Both functions are implemented via FFI call to the `clock_gettime()`.
> ---
>   perf/utils/clock.lua | 35 +++++++++++++++++++++++++++++++++++
>   1 file changed, 35 insertions(+)
>   create mode 100644 perf/utils/clock.lua
>
> diff --git a/perf/utils/clock.lua b/perf/utils/clock.lua
> new file mode 100644
> index 00000000..cf708194
> --- /dev/null
> +++ b/perf/utils/clock.lua
> @@ -0,0 +1,35 @@
> +local ffi = require('ffi')
> +
> +ffi.cdef[[
> +struct timespec {
> +  long tv_sec; /* Seconds. */
> +  long tv_nsec; /* Nanoseconds. */
> +};
> +
> +int clock_gettime(int clockid, struct timespec *tp);
> +]]
> +
> +local C = ffi.C
> +
> +-- Wall clock.
> +local CLOCK_REALTIME = 0
> +-- CPU time consumed by the process.
> +local CLOCK_PROCESS_CPUTIME_ID = 2
> +
> +-- All functions below returns the corresponding elapsed time in
> +-- seconds.
> +local M = {}
> +
> +local timespec = ffi.new('struct timespec[1]')
> +
> +function M.realtime()
> +  C.clock_gettime(CLOCK_REALTIME, timespec)
> +  return tonumber(timespec[0].tv_sec) + tonumber(timespec[0].tv_nsec) / 1e9
> +end
> +
> +function M.process_cputime()
> +  C.clock_gettime(CLOCK_PROCESS_CPUTIME_ID, timespec)
> +  return tonumber(timespec[0].tv_sec) + tonumber(timespec[0].tv_nsec) / 1e9
> +end
> +
> +return M