tsc.c

Go to the documentation of this file.

// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <linux/types.h>

#include "tsc.h"

u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
{
    u64 t, quot, rem;

    t = ns - tc->time_zero;
    quot = t / tc->time_mult;
    rem  = t % tc->time_mult;
    return (quot << tc->time_shift) +
           (rem << tc->time_shift) / tc->time_mult;
}

u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
{
    u64 quot, rem;

    quot = cyc >> tc->time_shift;
    rem  = cyc & (((u64)1 << tc->time_shift) - 1);
    return tc->time_zero + quot * tc->time_mult +
           ((rem * tc->time_mult) >> tc->time_shift);
}

u64 __weak rdtsc(void)
{
    return 0;
}