[linux-audio-dev] timesetevent alternative
sbenno at gardena.net
Sun May 8 16:22:46 UTC 2005
But what's the exact behaviour in 2.6 kernels then ?
Does nanosleep() provide non-busywait usec precision using hires timers,
or does it simply do the same as usleep() ?
Eg providing only 1/HZ precison.
Lee Revell wrote:
>>nanosleep() might be a bit more precise than usleep() but for low sleep
>>values ( AFAIK < 2msec ) it
>>busywaits when you run your app SCHED_FIFO which in the case of
>>sustained streams of low sleep values
>>could chew up all the CPU, not idea for real time audio apps.
>Not anymore. From man 2 nanosleep:
> Old behaviour
> In order to support applications requiring much more precise
>pauses (e.g., in order to control some time-critical hardware),
>nanosleep would handle pauses of up
> to 2 ms by busy waiting with microsecond precision when called
>from a process scheduled under a real-time policy like SCHED_FIFO or
>SCHED_RR. This special
> extension was removed in kernel 2.5.39, hence is still present in
>current 2.4 kernels, but not in 2.6 kernels.
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