On 07/15/2010 01:07 PM, Ralf Mardorf wrote: > On Thu, 2010-07-15 at 12:55 +0200, Clemens Ladisch wrote: >> Ralf Mardorf wrote: >>> - instead of dev.hpet.max-user-freq=64 I'll try 1024 or 2048 as Robin >>> mentioned >> >> This parameter will not have any effect on anything because there is no >> program that uses the HPET timers from userspace.
That'd be correct if Ralf would stick to 'amidiplay' and friends for his tests. There are a couple of audio-tools who can use either RTC or HPET for timing, although most of them need an option to explicitly enable it. >> When high-resolution >> timers are used by ALSA, this is done inside the kernel where there is >> no limit on the maximum frequency. Thanks for that explanation. It makes perfect sense. I take it the same must be true for dev.rtc.max-user-freq as well. BTW. Do you know the unit of these values? cat /sys/class/rtc/rtc0/max_user_freq cat /proc/sys/dev/hpet/max-user-freq are they Hz? linux-2.6/Documentation/hpet.txt does not mention it at all and linux-2.6/Documentation/rtc.txt hints it's Hz but does not explicitly say so. >> Regards, >> Clemens > > IIRC someone on jack-devel mailing list had issues when using mplayer > with the value 64 and it was solved when using the value 1024. But as I > mentioned before, for my USB MIDI there was a difference between system > timer and hr timer, but there was no difference for the value 64 and > 1024, when using hr timer. > > Btw. I don't understand what a maximum frequency in the context does > mean. If 64 or 1024 should have impact, what would be the result? > > System timer for a kernel-rt is set up to 1000Hz and hr timer is at > 1000000000Hz. > > What is 'max-user-freq' for? It limits the maximum frequency at which user-space applications can [request to] receive "wakeup calls" from the hr-timer. see also the "Timers" thread on LAD last November: http://linuxaudio.org/mailarchive/lad/2009/11/7/161647 > Cheers! > > Ralf > > best, robin -- Robin Gareus mail: ro...@gareus.org site: http://gareus.org/ chat: xmpp:rgar...@ik.nu blog: http://rg42.org/ lab : http://citu.fr/ Public Key at http://pgp.mit.edu/ Fingerprint : 7107 840B 4DC9 C948 076D 6359 7955 24F1 4F95 2B42 _______________________________________________ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev