diff options
Diffstat (limited to 'examples/performance-thread/common/lthread_timer.h')
| -rw-r--r-- | examples/performance-thread/common/lthread_timer.h | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/examples/performance-thread/common/lthread_timer.h b/examples/performance-thread/common/lthread_timer.h index b5e6fb0e..2d147577 100644 --- a/examples/performance-thread/common/lthread_timer.h +++ b/examples/performance-thread/common/lthread_timer.h @@ -42,11 +42,22 @@ static inline uint64_t _ns_to_clks(uint64_t ns) { - unsigned __int128 clkns = rte_get_tsc_hz(); + /* + * clkns needs to be divided by 1E9 to get ns clocks. However, + * dividing by this first would lose a lot of accuracy. + * Dividing after a multiply by ns, could cause overflow of + * uint64_t if ns is about 5 seconds [if we assume a max tsc + * rate of 4GHz]. Therefore we first divide by 1E4, then + * multiply and finally divide by 1E5. This allows ns to be + * values many hours long, without overflow, while still keeping + * reasonable accuracy. + */ + uint64_t clkns = rte_get_tsc_hz() / 1e4; clkns *= ns; - clkns /= 1000000000; - return (uint64_t) clkns; + clkns /= 1e5; + + return clkns; } |