Re: [Qemu-devel] [PATCH 1/2] audio: honor QEMU_AUDIO_TIMER_PERIOD instead of waking up every *nano* second

[Alex Bligh]

On 9 Oct 2013, at 20:42, Hans de Goede wrote:

> Now that we no longer have MIN_REARM_TIMER_NS a bug in the audio subsys has
> clearly shown it self by trying to make a timer fire every nano second.
> 
> Note we have a similar problem in 1.6, 1.5 and older but there
> MIN_REARM_TIMER_NS limits the wakeups caused by audio being active to
> 4000 times / second. This still causes a host cpu load of 50 % for simply
> playing audio, where as with this patch git master is at 13%, so we should
> backport this to 1.5 and 1.6 too.
> 
> Note this will not apply to 1.5 and 1.6 as is.
> 
> Cc: address@hidden
> Signed-off-by: Hans de Goede <address@hidden>
> ---
> audio/audio.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/audio/audio.c b/audio/audio.c
> index af4cdf6..b3db679 100644
> --- a/audio/audio.c
> +++ b/audio/audio.c
> @@ -1124,7 +1124,8 @@ static int audio_is_timer_needed (void)
> static void audio_reset_timer (AudioState *s)
> {
>     if (audio_is_timer_needed ()) {
> -        timer_mod (s->ts, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + 1);
> +        timer_mod (s->ts,
> +            qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + conf.period.ticks);

This assumes conf.period.ticks is in nanoseconds. That seems wrong.
Suggest multiplying by SCALE_US or SCALE_MS.

Alex

>     }
>     else {
>         timer_del (s->ts);
> -- 
> 1.8.3.1
> 
> 
> 

-- 
Alex Bligh