[PlanetCCRMA] "audiophile tweaks" for fedora? (using HPET high precision timer for digital audio clock)

[Niels Mayer]

Supposedly, one can improve the sound on Linux without resorting to a rubidium
wordclock <http://www.antelopeaudio.com/en/products_iso_10m.html> ( :-) ) by
using HPET high precision timers for the digital audio clock.

Does this apply when using a "pro" soundcard that has it's own digital
timebase (I note config options for this in envy24control, as well as a
quartz crystal component in proximity to the  ice1712 sound chip on the
M-audio delta 66)??

Has anybody tried booting w/ the suggested "clocksource=hpet" && does it
work?  Does any of this make sense to even look into given that the quartz
crystal on the soundcard is probably good enough,  and is kept as
temperature-stable by the graphics card fan blowing heat all over the
soundcard :-)  -- a poor man's "oven control" like in this product:
http://www.antelopeaudio.com/en/products_iso_ocx.htm

FYI, some notes on this pasted from a discussion in #fedora, combined w/ my
own notes:

(08:43:44 AM) fenris02: npm, all the audiophile tweaks? they're already in
fedora. just turn them on.
(08:44:14 AM) npm: what are the audiophile tweaks?
(08:44:50 AM) fenris02: npm, yum install tuned rtkit; chrt -f -p 99 `pgrep
softirq`; .... and see the pa page on adding yourself to the group to enable
(08:45:34 AM) fenris02: npm, the only other one is appending
"clocksource=hpet" to the kernel line in grub.
(08:46:11 AM) npm: oh interesting. use the hpet timer to get a more accurate
clock?
(08:46:18 AM) fenris02: npm, yes
(08:46:20 AM) npm: that sounds like something i would do
(08:46:32 AM) fenris02: npm,
/sys/devices/system/clocksource/clocksource0/available_clocksource
(08:46:36 AM) fenris02: err, cat
/sys/devices/system/clocksource/clocksource0/available_clocksource

gnulem-54-~> cat /sys/devices/system/clocksource/clocksource0/
available_clocksource  current_clocksource
gnulem-54-~> cat
/sys/devices/system/clocksource/clocksource0/current_clocksource
tsc

(09:00:45 AM) npm: fenris02: is 'tuned' a necessary part of your audiophile
suggestions? (i already have rtkit installed and messages indicate it's
"working")... my current clocksource is "tsc" and "hpet" is available... so
if i wanted to just get that, use suggestion 'appending "clocksource=hpet"
to the kernel line in grub.' ??
(09:01:32 AM) npm: ^^^ re " fenris02: npm, yum install tuned rtkit; chrt -f
-p 99 `pgrep softirq`; .... and see the pa page on adding yourself to the
group to enable"

gnulem-57-~> yum info '*tuned*'
Loaded plugins: refresh-packagekit
Available Packages
Name       : tuned
Arch       : noarch
Version    : 0.2.5
Release    : 0.1.fc12
Size       : 46 k
Repo       : fedora
Summary    : A dynamic adaptive system tuning daemon
URL        : https://fedorahosted.org/tuned/
License    : GPLv2+
Description: The tuned package contains a daemon that tunes system settings
           : dynamically. It does so by monitoring the usage of several
system
           : components periodically. Based on that information components
will
           : then be put into lower or higher power saving modes to adapt to
           : the current usage. Currently only ethernet network and ATA
           : harddisk devices are implemented.

Name       : tuned-utils
Arch       : noarch
Version    : 0.2.5
Release    : 0.1.fc12
Size       : 14 k
Repo       : fedora
Summary    : Disk and net statistic monitoring systemtap scripts
URL        : https://fedorahosted.org/tuned/
License    : GPLv2+
Description: The tuned-utils package contains several systemtap scripts to
           : allow detailed manual monitoring of the system. Instead of the
           : typical IO/sec it collects minimal, maximal and average time
           : between operations to be able to identify applications that
behave
           : power inefficient (many small operations instead of fewer large
           : ones).


Niels
http://nielsmayer.com
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