16 Dec
2009
16 Dec
'09
3:17 p.m.
For some reason, even though HPET is configured into this kernel,
/dev/hpet does not exist. Do I really need it, and if so, how do I fix it?
J.E.B.
16 Dec
16 Dec
4:01 p.m.
On 16/12/2009, "Jonathan E. Brickman" <jeb(a)joshuacorps.org> wrote:
For some reason, even though HPET is configured into
this kernel,
/dev/hpet does not exist. Do I really need it, and if so, how do I fix it?
What does cat /proc/driver/rtc tell you?
On my system it says HPET is emulated.
J.E.B.
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4:26 p.m.
On Wednesday 16 December 2009 22:01:02 james morris wrote:
On 16/12/2009, "Jonathan E. Brickman"
<jeb(a)joshuacorps.org> wrote:
Here is mine for what it is worth:
$ cat /proc/driver/rtc
rtc_time : 22:25:17
rtc_date : 2009-12-16
alrm_time : 00:00:00
alrm_date : ****-**-**
alarm_IRQ : no
alrm_pending : no
24hr : yes
periodic_IRQ : no
update_IRQ : no
HPET_emulated : no
DST_enable : no
periodic_freq : 1024
batt_status : okay
No emulation here or any indication of hpet?
For some reason, even though HPET is configured
into this kernel,
/dev/hpet does not exist. Do I really need it, and if so, how do I fix
it?
What does cat /proc/driver/rtc tell you?
On my system it says HPET is emulated.
7:40 p.m.
For some
reason, even though HPET is configured into this kernel,
/dev/hpet does not exist. Do I really need it, and if so, how do I fix it?
What does cat /proc/driver/rtc tell you?
On my system it says HPET is emulated.
17 Dec
17 Dec
11:06 a.m.
On Wed, Dec 16, 2009 at 6:42 PM, Jonathan E. Brickman
<jeb(a)joshuacorps.org> wrote:
Should CONFIG_HPET_EMULATE_RTC be set to n on a
realtime kernel? Is
there something else which might invalidate CONFIG_HPET=y ?
the RTC device is unrelated to HPET. your kernel can have HPET support
but if your h/w doesn't, you don't get /dev/hpet. My motherboard, for
example, does not have an HPET device.
8:22 p.m.
New subject: /dev/hpet, depends on kernel?
Should
CONFIG_HPET_EMULATE_RTC be set to n on a realtime kernel? Is
there something else which might invalidate CONFIG_HPET=y ?
the RTC device is unrelated to HPET. your kernel can have HPET support
but if your h/w doesn't, you don't get /dev/hpet. My motherboard, for
example, does not have an HPET device.
18 Dec
18 Dec
12:48 a.m.
New subject: 64-bit improves audio performance?
Well. No change in Jack behavior with LXDE, no change from total
removal of Pulse. Now I really wonder. 64-bit has definitely upped my
GUI speed, often tripled my WWW speed -- but it has either not touched
audio (synth and Jack) performance and latency, or has hurt it
slightly! Anyone seen the same thing?
J.E.B.
That is interesting. I am interested principally because I'm seeing
xruns and am hunting for causes, and that stood out.
Checked the BIOS; HPET is there, already turned on. Running the
vanilla-install Debian Testing (AMD64) kernel, package
"linux-image-2.6.30-2-amd64" version 2.6.30-8, I do have a /dev/hpet.
Running any of six or seven slightly different but very clean rtlinux
builds (vanilla kernel source of 2.6.31.6, plus rtlinux
patch-2.6.31.6-rt19.bz2), .config options verified and reverified very
carefully, I don't have a /dev/hpet. Anything I should check? Do you
think I should get on a kernel dev list?
But I understand now that hpet may have little or nothing to do with the
xrun problem. At least part of the symptomatology, is that Pulse
talking to Jack on 64-bit Debian Testing / Gnome with GUI sound events
off, seems to eat a whole lot more of Jack's DSP capacity than the same
combination on 32-bit / LXDE. On 32-bit, Pulse at idle ate zero CPU;
now on 64-bit, Pulse at idle is eating about 2%. I'm wondering right
this minute if Gnome keeps its default sound open, delivering full-bore
(albeit silent) audio even when it's told not to do so.
I suppose I'll try LXDE. But any suggestions will be very much appreciated.
J.E.B.
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Should CONFIG_HPET_EMULATE_RTC be set to n on a
realtime kernel? Is
there something else which might invalidate CONFIG_HPET=y ?
the RTC device is unrelated to HPET. your kernel can have HPET support
but if your h/w doesn't, you don't get /dev/hpet. My motherboard, for
example, does not have an HPET device.
1:12 p.m.
New subject: 64-bit improves audio performance?
On Thu, 17 Dec 2009, Jonathan E. Brickman wrote:
Well. No change in Jack behavior with LXDE, no change
from total
removal of Pulse. Now I really wonder. 64-bit has definitely upped
my GUI speed, often tripled my WWW speed -- but it has either not
touched audio (synth and Jack) performance and latency, or has hurt it
slightly! Anyone seen the same thing?
Well, I will say that I've got 8GB of physical memory, which I'm seeing
all of because I'm running 64-bit, and Ardour absolutely LOVES that. :)
It's like my whole project seems to fit in memory and nothing ever loads
from disk twice, among other benefits...
--
+ Brent A. Busby + "We've all heard that a million monkeys
+ UNIX Systems Admin + banging on a million typewriters will
+ University of Chicago + eventually reproduce the entire works of
+ Physical Sciences Div. + Shakespeare. Now, thanks to the Internet,
+ James Franck Institute + we know this is not true." -Robert Wilensky
23 Dec
23 Dec
2:59 p.m.
New subject: 64-bit improves audio performance?
Well. No
change in Jack behavior with LXDE, no change from total
removal of Pulse. Now I really wonder. 64-bit has definitely upped
my GUI speed, often tripled my WWW speed -- but it has either not
touched audio (synth and Jack) performance and latency, or has hurt it
slightly! Anyone seen the same thing?
Well, I will say that I've got 8GB of physical memory, which I'm seeing
all of because I'm running 64-bit, and Ardour absolutely LOVES that. :)
It's like my whole project seems to fit in memory and nothing ever loads
from disk twice, among other benefits...
18 Dec
18 Dec
8:18 a.m.
New subject: /dev/hpet, depends on kernel?
On Friday 18 December 2009 01:24:48 Jonathan E. Brickman wrote:
But I understand now that hpet may have little or
nothing to do with the
xrun problem.
I just discovered Jack2's fantastic profiling options. Have a look at:
http://www.grame.fr/~letz/Timing.pdf to see the kind of data it can give you.
Should at the least tell you if the problem is in the kernel or in userland.
Thanks sletz and others for this very useful addition to Jack!
Joakim
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9 comments
6 participants
participants (6)
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Brent Busby -
David Baron -
james morris -
Joakim Hernberg -
Jonathan E. Brickman -
Paul Davis