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| /openbmc/linux/drivers/cpufreq/ |
| H A D | pmac64-cpufreq.c | 45a428eb Mon Sep 30 15:44:31 CDT 2013 Aaro Koskinen <aaro.koskinen@iki.fi> cpufreq: pmac64: speed up frequency switch
Some functions on switch path use msleep() which is inaccurate, and
depends on HZ. With HZ=100 msleep(1) takes actually over ten times longer.
Using usleep_range() we get more accurate sleeps.
I measured the "pfunc_slewing_done" polling to take 300us at max (on
2.3GHz dual-processor Xserve G5), so using 500us sleep there should
be fine.
With the patch, g5_switch_freq() duration drops from ~50ms to ~10ms on
Xserve with HZ=100.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
45a428eb Mon Sep 30 15:44:31 CDT 2013 Aaro Koskinen <aaro.koskinen@iki.fi> cpufreq: pmac64: speed up frequency switch
Some functions on switch path use msleep() which is inaccurate, and
depends on HZ. With HZ=100 msleep(1) takes actually over ten times longer.
Using usleep_range() we get more accurate sleeps.
I measured the "pfunc_slewing_done" polling to take 300us at max (on
2.3GHz dual-processor Xserve G5), so using 500us sleep there should
be fine.
With the patch, g5_switch_freq() duration drops from ~50ms to ~10ms on
Xserve with HZ=100.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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