7 Nov
2009
7 Nov
'09
6:22 p.m.
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(a)alice-dsl.net> wrote:
From: Ralf Mardorf <ralf.mardorf(a)alice-dsl.net>
Subject: Re: [LAD] timers
To: "Paul Davis" <paul(a)linuxaudiosystems.com>om>, "Emanuel Rumpf"
<xbran(a)web.de>de>, "James Warden" <warjamy(a)yahoo.com>
Cc: linux-audio-dev(a)lists.linuxaudio.org
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