[pulseaudio-discuss] [PATCH] use CLOCK_MONOTONIC_COARSE to reduce the system call

Arun Raghavan arun.raghavan at collabora.co.uk
Thu Mar 29 21:48:32 PDT 2012


On Thu, 2012-03-29 at 21:31 +0800, Deng Zhenrong wrote:
> According to the description below:
>         http://lkml.org/lkml/2009/7/17/258
> There are two benefits:
> a) it doesn't need to access the hardware.
> b) avoid the syscall by using vdso clock_gettime().
> The cons is the CLOCK_MONOTONIC_COARSE returns the time at the last
> tick.

As Pierre mentions, we actually _want_ high resolution time sources for
our uses. We use these timers to predict when the audio buffer will be
nearing being empty so that we can wake up and fill the buffer again.
Having a coarse timer for this purpose would mean that we can be woken
up late, causing the device to underrun and users to hear glitches.


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