[LAU] XanMod kernel
Tim E. Real
termtech at rogers.com
Wed Jun 10 00:08:44 CEST 2020
On 6/9/20 5:36 PM, Tim E. Real wrote:
> On 6/9/20 11:27 AM, Jeremy Jongepier wrote:
>> Hello Tim,
>>> My understanding is that ALSA placed a hard-coded limit on the
>>> snd-hrtimer of around 1024Hz a couple of years ago.
>>> The snd-hrtimer used to be able to be set very high frequencies
>>> until one day it wouldn't. I contacted ALSA and they told me
>>> about this new hard-coded limit.
>>> This sent me scrambling to re-order the midi timer preference
>>> in MusE because it seems the RTC timer is now the only timer
>>> that can give you anything above 1024Hz.
>>> Have I got this correct?
>> I checked sound/core/hrtimer.c of a current linux kernel source and I
>> don't see any limits of 1000 or 1024. And when I check on my system with
>> `cat /proc/asound/timers` I see the resolution of the system timer is
>> 1000 µs, so 1 ms (which I think equals the 1000 HZ kernel setting I use)
>> while the HR timer has a resolution of 0.001 µs, so 1 ns. If I search
>> for .resolution in /proc/timer_list I see that same value, so 1 ns. So
>> my guess is that snd-hrtimer goes way beyond 1000 HZ and doesn't seem to
>> have a hard-coded limit of itself.
> Hi, yes I got the same 'normal' reported resolution and frequencies
> but behind the scenes it had the hard-coded limit.
> I pointed that out to ALSA, that there is no indication at all that
> this limit is applied,
> until one actually tries to use it.
FYI Here's the thread from 2017,
maybe things have changed since then?
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