On Mon, 15 Mar 2021 08:18:29 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx> wrote:
> If there is information for TSC to nanoseconds conversion in the trace
> file metadata, use it to recalculate the timestamps of all events.
>
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
> ---
> lib/trace-cmd/trace-input.c | 28 ++++++++++++++++++++++++----
> 1 file changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
> index 65081007..dc9ac1d3 100644
> --- a/lib/trace-cmd/trace-input.c
> +++ b/lib/trace-cmd/trace-input.c
> @@ -1276,17 +1276,37 @@ static unsigned long long timestamp_correct(unsigned long long ts,
> &host->ts_samples[mid+1]);
> }
>
I would add a comment saying that the below function was taken from the
Linux kernel.
-- Steve
> +static unsigned long long mul_u64_u32_shr(unsigned long long a,
> + unsigned long long mul, unsigned int shift)
> +{
> + unsigned int ah, al;
> + unsigned long long ret;
> +
> + al = a;
> + ah = a >> 32;
> +
> + ret = (al * mul) >> shift;
> + if (ah)
> + ret += (ah * mul) << (32 - shift);
> +
> + return ret;
> +}
> +
> static unsigned long long timestamp_calc(unsigned long long ts,
> struct tracecmd_input *handle)
> {
> - unsigned long long tstamp;
> + unsigned long long t;
>
> - tstamp = timestamp_correct(ts, handle);
> + t = timestamp_correct(ts, handle);
>
> if (handle->ts2secs)
> - tstamp *= handle->ts2secs;
> + t *= handle->ts2secs;
> + else if (handle->tsc_calc.mult) {
> + t = mul_u64_u32_shr(t, handle->tsc_calc.mult, handle->tsc_calc.shift);
> + t += handle->tsc_calc.offset;
> + }
>
> - return tstamp;
> + return t;
> }
>
> /*
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