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authorAshwin Chaugule <ashwinc@quicinc.com>2009-09-01 23:03:33 -0400
committerThomas Gleixner <tglx@linutronix.de>2009-09-15 17:09:44 +0200
commit7403f41f19574d6805197e9b97dfa7592003be10 (patch)
tree8d849ac38a64a60fbe06f9f2c8c6b26697fad74f /ipc
parent12e09337fe238981cb0c87543306e23775d1a143 (diff)
downloadop-kernel-dev-7403f41f19574d6805197e9b97dfa7592003be10.zip
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hrtimer: Eliminate needless reprogramming of clock events device
On NOHZ systems the following timers, - tick_nohz_restart_sched_tick (tick_sched_timer) - hrtimer_start (tick_sched_timer) are reprogramming the clock events device far more often than needed. No specific test case was required to observe this effect. This occurres because there was no check to see if the currently removed or restarted hrtimer was: 1) the one which previously armed the clock events device. 2) going to be replaced by another timer which has the same expiry time. Avoid the reprogramming in hrtimer_force_reprogram when the new expiry value which is evaluated from the clock bases is equal to cpu_base->expires_next. This results in faster application startup time by ~4%. [ tglx: simplified initial solution ] Signed-off-by: Ashwin Chaugule <ashwinc@quicinc.com> LKML-Reference: <4AA00165.90609@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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