diff options
Diffstat (limited to 'usr/src/uts/common/os/timers.c')
| -rw-r--r-- | usr/src/uts/common/os/timers.c | 49 |
1 files changed, 37 insertions, 12 deletions
diff --git a/usr/src/uts/common/os/timers.c b/usr/src/uts/common/os/timers.c index 61acc6cf97..53be806026 100644 --- a/usr/src/uts/common/os/timers.c +++ b/usr/src/uts/common/os/timers.c @@ -22,6 +22,7 @@ /* * Copyright 2010 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. + * Copyright 2016 Joyent, Inc. */ /* @@ -1172,6 +1173,14 @@ timespectohz64(timespec_t *tv) void hrt2ts(hrtime_t hrt, timestruc_t *tsp) { +#if defined(__amd64) + /* + * The cleverness explained above is unecessary on x86_64 CPUs where + * modern compilers are able to optimize down to faster operations. + */ + tsp->tv_sec = hrt / NANOSEC; + tsp->tv_nsec = hrt % NANOSEC; +#else uint32_t sec, nsec, tmp; tmp = (uint32_t)(hrt >> 30); @@ -1193,20 +1202,28 @@ hrt2ts(hrtime_t hrt, timestruc_t *tsp) } tsp->tv_sec = (time_t)sec; tsp->tv_nsec = nsec; +#endif /* defined(__amd64) */ } /* * Convert from timestruc_t to hrtime_t. - * - * The code below is equivalent to: - * - * hrt = tsp->tv_sec * NANOSEC + tsp->tv_nsec; - * - * but requires no integer multiply. */ hrtime_t ts2hrt(const timestruc_t *tsp) { +#if defined(__amd64) || defined(__i386) + /* + * On modern x86 CPUs, the simple version is faster. + */ + return ((tsp->tv_sec * NANOSEC) + tsp->tv_nsec); +#else + /* + * The code below is equivalent to: + * + * hrt = tsp->tv_sec * NANOSEC + tsp->tv_nsec; + * + * but requires no integer multiply. + */ hrtime_t hrt; hrt = tsp->tv_sec; @@ -1215,6 +1232,7 @@ ts2hrt(const timestruc_t *tsp) hrt = (hrt << 7) - hrt - hrt - hrt; hrt = (hrt << 9) + tsp->tv_nsec; return (hrt); +#endif /* defined(__amd64) || defined(__i386) */ } /* @@ -1246,6 +1264,13 @@ tv2hrt(struct timeval *tvp) void hrt2tv(hrtime_t hrt, struct timeval *tvp) { +#if defined(__amd64) + /* + * Like hrt2ts, the simple version is faster on x86_64. + */ + tvp->tv_sec = hrt / NANOSEC; + tvp->tv_usec = (hrt % NANOSEC) / (NANOSEC / MICROSEC); +#else uint32_t sec, nsec, tmp; uint32_t q, r, t; @@ -1267,17 +1292,17 @@ hrt2tv(hrtime_t hrt, struct timeval *tvp) sec++; } tvp->tv_sec = (time_t)sec; -/* - * this routine is very similar to hr2ts, but requires microseconds - * instead of nanoseconds, so an interger divide by 1000 routine - * completes the conversion - */ + /* + * this routine is very similar to hr2ts, but requires microseconds + * instead of nanoseconds, so an interger divide by 1000 routine + * completes the conversion + */ t = (nsec >> 7) + (nsec >> 8) + (nsec >> 12); q = (nsec >> 1) + t + (nsec >> 15) + (t >> 11) + (t >> 14); q = q >> 9; r = nsec - q*1000; tvp->tv_usec = q + ((r + 24) >> 10); - +#endif /* defined(__amd64) */ } int |