Re: [LAD] timers

Ralph,

As I said, this startup script is something I wrote a long time ago. The max-user-freq is for apps like video players, some polling frequency for improving the playback performance (smoother playback). The default used to be 64Hz. Increasing it to 1024 was making mplayer or xine much more performant.

Actually, I will reboot my DAW when I have some spare time without this startup script (except for the /dev/hpet group permission) and see what the newer kernel sets as default.

J.

--- On Sat, 11/7/09, Ralf Mardorf <ralf.mardorf@email-addr-hidden-dsl.net> wrote:

> From: Ralf Mardorf <ralf.mardorf@email-addr-hidden-dsl.net>
> Subject: Re: [LAD] timers
> To: "Paul Davis" <paul@email-addr-hidden>, "Emanuel Rumpf" <xbran@email-addr-hidden.de>, "James Warden" <warjamy@email-addr-hidden>
> Cc: linux-audio-dev@email-addr-hidden
> Date: Saturday, November 7, 2009, 4:40 PM
> Summarized:
>
> I guess my mobo supports hpet :).
>
> $ dmesg | grep -i hpet
> [    0.000000] ACPI: HPET 77EE89C0, 0038 (r1
> ATI    ASUSACPI 42302E31 AWRD   
>    98)
> [    0.000000] ACPI: HPET id: 0x8200 base:
> 0xfed00000
> [    0.000999] hpet clockevent registered
> [    0.000999] HPET: 4 timers in total, 0 timers
> will be used for per-cpu timer
> [    0.177117] hpet0: at MMIO 0xfed00000, IRQs 2,
> 8, 0, 0
> [    0.177123] hpet0: 4 comparators, 32-bit
> 14.318180 MHz counter
> [    1.166497] rtc0: alarms up to one month, 242
> bytes nvram, hpet irqs
>
> 1. The kernel has to support it too.
> 2. If the kernel-rt does support it, I need to add a
> startup script:
>
>    chgrp audio /dev/hpet
>    echo 1024 >
> /proc/sys/dev/hpet/max-user-freq
>    modprobe snd-hrtimer
>      
> Here I don't understand what the value 1024, written to
> max-user-freq does mean ;).
>
> 3. I need to launch JACK2 with the option "-c", e.g.:
>
> jackd -Rc h -dalsa -dhw:0 -r96000 -p512 -n2 -Xseq
>
> 4. The sequencer timing source needs to be set up to hpet
> or hrtimer too?
> rosegarden -v 1.7.3 and qtractor -v 0.4.3.1418 aren't able
> to do it?
>
> Or will the "-c" option for JACK2 replace a chosen timer
> for Qtractor or Rosegarden with hpet?
>
> ---
>
> "With a Linux kernel, you need the newer "rtc-cmos"
> hardware clock device driver rather than the original "rtc"
> driver." (http://en.wikipedia.org/wiki/High_Precision_Event_Timer)
>
> I guess this is within the vanilla kernel source code?!
>
> Cheers,
> Ralf
>

      
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Received on Sun Nov 8 04:15:01 2009