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| author | Aaro Koskinen <Aaro.Koskinen@nokia.com> | 2009-03-04 10:07:41 -0800 |
|---|---|---|
| committer | Tony Lindgren <tony@atomide.com> | 2009-03-04 10:07:41 -0800 |
| commit | 80ea3bac3a47bc73efa334d0dd57099d0ff14216 (patch) | |
| tree | 2312b3917a7ac97bfe59d0419122714a118cbcc3 /Documentation/rt-mutex-design.txt | |
| parent | 87d99d6f7ee3ec73b2b0212427b173502ec9d6cb (diff) | |
| download | kernel-crypto-80ea3bac3a47bc73efa334d0dd57099d0ff14216.tar.gz kernel-crypto-80ea3bac3a47bc73efa334d0dd57099d0ff14216.tar.xz kernel-crypto-80ea3bac3a47bc73efa334d0dd57099d0ff14216.zip | |
ARM: OMAP: sched_clock() corrected
After my OMAP3 board has been running for a while, I'm seeing weird
latency traces like this:
sh-1574 0d.h2 153us : do_timer (tick_do_update_jiffies64)
sh-1574 0d.h2 153us : update_wall_time (do_timer)
sh-1574 0d.h2 153us!: omap_32k_read (update_wall_time)
sh-1574 0d.h2 1883us : update_xtime_cache (update_wall_time)
sh-1574 0d.h2 1883us : clocksource_get_next (update_wall_time)
sh-1574 0d.h2 1883us+: _spin_lock_irqsave (clocksource_get_next)
and after a while:
sh-17818 0d.h3 153us : do_timer (tick_do_update_jiffies64)
sh-17818 0d.h3 153us : update_wall_time (do_timer)
sh-17818 0d.h3 153us!: omap_32k_read (update_wall_time)
sh-17818 0d.h3 1915us : update_xtime_cache (update_wall_time)
sh-17818 0d.h3 1915us+: clocksource_get_next (update_wall_time)
sh-17818 0d.h3 1945us : _spin_lock_irqsave (clocksource_get_next)
Turns out that sched_clock() is using cyc2ns(), which returns NTP
adjusted time. The sched_clock() frequency should not be adjusted. The
patch deletes omap_32k_ticks_to_nsecs() and rewrites sched_clock()
to do the conversion using the constant multiplier.
Signed-off-by: Aaro Koskinen <Aaro.Koskinen@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Diffstat (limited to 'Documentation/rt-mutex-design.txt')
0 files changed, 0 insertions, 0 deletions