diff options
Diffstat (limited to 'tools/perf/arch/x86/util/tsc.c')
-rw-r--r-- | tools/perf/arch/x86/util/tsc.c | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/tools/perf/arch/x86/util/tsc.c b/tools/perf/arch/x86/util/tsc.c new file mode 100644 index 0000000..9570c2b --- /dev/null +++ b/tools/perf/arch/x86/util/tsc.c @@ -0,0 +1,59 @@ +#include <stdbool.h> +#include <errno.h> + +#include <linux/perf_event.h> + +#include "../../perf.h" +#include "../../util/types.h" +#include "../../util/debug.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 & ((1 << tc->time_shift) - 1); + return tc->time_zero + quot * tc->time_mult + + ((rem * tc->time_mult) >> tc->time_shift); +} + +int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc, + struct perf_tsc_conversion *tc) +{ + bool cap_usr_time_zero; + u32 seq; + int i = 0; + + while (1) { + seq = pc->lock; + rmb(); + tc->time_mult = pc->time_mult; + tc->time_shift = pc->time_shift; + tc->time_zero = pc->time_zero; + cap_usr_time_zero = pc->cap_usr_time_zero; + rmb(); + if (pc->lock == seq && !(seq & 1)) + break; + if (++i > 10000) { + pr_debug("failed to get perf_event_mmap_page lock\n"); + return -EINVAL; + } + } + + if (!cap_usr_time_zero) + return -EOPNOTSUPP; + + return 0; +} |