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jack2, -c hpet ?

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Jonathan E. Brickman

11 Sep 2010 11 Sep '10

6:18 a.m.

I have stabilized and accelerated things a lot with clocksource=hpet on the kernel line; but I am wondering if I could get rid of my very very few remaining xruns with "-c hpet" in the jackd command line. Only thing is, jackd is reporting hpet as unsupported / not implemented. Thoughts, anyone? J.E.B.

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Paul Davis

11 Sep 11 Sep

7:15 p.m.

On Sat, Sep 11, 2010 at 12:18 AM, Jonathan E. Brickman <jeb(a)ponderworthy.com> wrote:

I have stabilized and accelerated things a lot with clocksource=hpet on the kernel line; but I am wondering if I could get rid of my very very few remaining xruns with "-c hpet" in the jackd command line. Only thing is, jackd is reporting hpet as unsupported / not implemented. Thoughts, anyone?

HPET has as about as close to zero effect on xruns as is possible. To use it your kernel and hardware must support the HPET timer. If one or both of them do not you will see that message.

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Robin Gareus

9:51 p.m.

On 09/11/2010 07:15 PM, Paul Davis wrote:

On Sat, Sep 11, 2010 at 12:18 AM, Jonathan E. Brickman <jeb(a)ponderworthy.com> wrote:

I have stabilized and accelerated things a lot with clocksource=hpet on the kernel line; but I am wondering if I could get rid of my very very few remaining xruns with "-c hpet" in the jackd command line. Only thing is, jackd is reporting hpet as unsupported / not implemented. Thoughts, anyone?

HPET has as about as close to zero effect on xruns as is possible.

More info on this can be found in a thread on LAD about a year ago: http://linuxaudio.org/mailarchive/lad/2009/11/10/161854

To use it your kernel and hardware must support the HPET timer. If one or both of them do not you will see that message.

Just for completeness: the message ("This system has no accessible HPET device (Device or resource busy") also shows if the user has no permission to access /dev/hpet best, robin

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Jonathan E. Brickman

10:29 p.m.

I have stabilized and accelerated things a lot with clocksource=hpet on the kernel line; but I am wondering if I could get rid of my very very few remaining xruns with "-c hpet" in the jackd command line. Only thing is, jackd is reporting hpet as unsupported / not implemented. Thoughts, anyone?

HPET has as about as close to zero effect on xruns as is possible.

More info on this can be found in a thread on LAD about a year ago: http://linuxaudio.org/mailarchive/lad/2009/11/10/161854

To use it your kernel and hardware must support the HPET timer. If one or both of them do not you will see that message.

Just for completeness: the message ("This system has no accessible HPET device (Device or resource busy") also shows if the user has no permission to access /dev/hpet best, robin

Gotcha. The thing is, I /think/ I can prove that my setup is compliant. Here are queries and results: [jeb@youngdavid realtimeconfigquickscan]$ ls -l /dev/hpet crw-rw---- 1 root audio 10, 228 Sep 11 09:30 /dev/hpet [jeb@youngdavid realtimeconfigquickscan]$ grep audio /etc/group audio:x:63:jeb [jeb@youngdavid realtimeconfigquickscan]$ dmesg | grep hpet Command line: ro root=/dev/mapper/vg_youngdavid-lv_root rd_LVM_LV=vg_youngdavid/lv_root rd_LVM_LV=vg_youngdavid/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us rhgb hpet=enable clocksource=hpet quiet selinux=0 rdblacklist=nouveau vga=0×318 nouveau.modeset=0 Kernel command line: ro root=/dev/mapper/vg_youngdavid-lv_root rd_LVM_LV=vg_youngdavid/lv_root rd_LVM_LV=vg_youngdavid/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us rhgb hpet=enable clocksource=hpet quiet selinux=0 rdblacklist=nouveau vga=0×318 nouveau.modeset=0 hpet clockevent registered hpet0: at MMIO 0xfeff0000, IRQs 2, 8, 31 hpet0: 3 comparators, 32-bit 25.000000 MHz counter Switching to clocksource hpet rtc0: alarms up to one year, y3k, 114 bytes nvram, hpet irqs [jeb@youngdavid realtimeconfigquickscan]$

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Jonathan E. Brickman
Paul Davis
Robin Gareus