diff options
| author | Abhilash Jindal <klock.android@gmail.com> | 2015-08-11 12:01:22 -0400 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-09-01 15:51:43 +0200 |
| commit | 72e624de6e6f0d5a638fbc23842aa76ae048e9e7 (patch) | |
| tree | 5752040aa7d5293ce0aa33a122f9900aa1f0fb63 /drivers/cpufreq/speedstep-lib.c | |
| parent | 309d0631cc329ca1051c631c89e0acc9b752cb4d (diff) | |
cpufreq: speedstep-lib: Use monotonic clock
Wall time obtained from do_gettimeofday is susceptible to sudden jumps due to
user setting the time or due to NTP.
Monotonic time is constantly increasing time better suited for comparing two
timestamps.
Signed-off-by: Abhilash Jindal <klock.android@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/speedstep-lib.c')
| -rw-r--r-- | drivers/cpufreq/speedstep-lib.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/drivers/cpufreq/speedstep-lib.c b/drivers/cpufreq/speedstep-lib.c index 4ab7a2156672..15d3214aaa00 100644 --- a/drivers/cpufreq/speedstep-lib.c +++ b/drivers/cpufreq/speedstep-lib.c @@ -386,7 +386,7 @@ unsigned int speedstep_get_freqs(enum speedstep_processor processor, unsigned int prev_speed; unsigned int ret = 0; unsigned long flags; - struct timeval tv1, tv2; + ktime_t tv1, tv2; if ((!processor) || (!low_speed) || (!high_speed) || (!set_state)) return -EINVAL; @@ -415,14 +415,14 @@ unsigned int speedstep_get_freqs(enum speedstep_processor processor, /* start latency measurement */ if (transition_latency) - do_gettimeofday(&tv1); + tv1 = ktime_get(); /* switch to high state */ set_state(SPEEDSTEP_HIGH); /* end latency measurement */ if (transition_latency) - do_gettimeofday(&tv2); + tv2 = ktime_get(); *high_speed = speedstep_get_frequency(processor); if (!*high_speed) { @@ -442,8 +442,7 @@ unsigned int speedstep_get_freqs(enum speedstep_processor processor, set_state(SPEEDSTEP_LOW); if (transition_latency) { - *transition_latency = (tv2.tv_sec - tv1.tv_sec) * USEC_PER_SEC + - tv2.tv_usec - tv1.tv_usec; + *transition_latency = ktime_to_us(ktime_sub(tv2, tv1)); pr_debug("transition latency is %u uSec\n", *transition_latency); /* convert uSec to nSec and add 20% for safety reasons */ |