Re: [seq24-users] timing
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From: Rob B. <rc...@fi...> - 2006-09-12 23:10:12
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What does your seq24 console output look like when you run with --stats ? Rob On 9/10/2006, "Ben Saylor" <ben...@fa...> wrote: >Here's an update on my progress with improving seq24's timing on my >system, in case it someone might find it useful or have any additional >insights. > >The following page has some useful information on priorities and other >things relating to MIDI timing and audio: >http://tapas.affenbande.org/?page_id=3D40 > >I increased seq24's realtime priority above Jack's by setting Jack's >priority to 80 and changing line 1009 in perform.cpp from >=09schp->sched_priority =3D 1; >to >=09schp->sched_priority =3D 85; >and starting seq24 with the --priority flag (BTW, it would be nice >if --priority accepted an integer argument for the desired priority; >that's what I expected to happen at first but found that it was hard >coded). > >I increased the priority and frequency of the RTC (this is what seq24 >uses for timing, right?): >=09chrt -f -p 98 `pidof "IRQ 8"` >=09echo 8192 > /proc/sys/dev/rtc/max-user-freq > >This seems to have improved MIDI timing. However, when CPU load is >somewhat high (~50% in my test setup), switching desktops, launching >non-realtime applications, and especially moving windows can cause huge >timing glitches. The sequence seems to pause and then catch up when I >stop dragging the window. While this is happening, the audio continues >to play, and while enough window-dragging will cause audio dropouts, >the MIDI timing seems to go bad first, even though I've given seq24 and >RTC higher priorities than the audio apps. I don't understand this, >and I don't understand why the timing should be affected so badly by >CPU activity caused by non-realtime processes, when all of the audio >and MIDI stuff has realtime priority. Here's the output of top, sorted >by priority: > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 9 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/0 >2342 root RT 0 10464 10m 1976 S 0.0 1.3 0:00.38 das_watchdog > 236 root -99 -5 0 0 0 S 0.0 0.0 0:00.00 IRQ 8 > 5815 me -91 0 35736 34m 2584 S 0.0 4.6 0:00.00 jackd > 5856 me -86 5 39068 11m 9952 S 0.1 1.6 0:05.58 seq24 > 5816 me -81 0 35736 34m 2584 S 0.8 4.6 0:12.37 jackd > 5817 me -80 0 29500 27m 16m S 0.0 3.7 0:04.44 qjackctl > 5823 me -80 5 51372 49m 7464 S 18.3 6.5 4:11.51 zynaddsubfx > 5828 me -80 5 61484 59m 26m S 1.4 7.8 0:22.76 hydrogen > >Then down below, there's another seq24 thread at priority -2. > >On Monday 21 August 2006 08:58, Ben Saylor wrote: >> Whoops, I meant to send this to the list. I will check on the kernel >> frequency when I get back to my computer. >> >> Rob Buse wrote: >> > Ben- >> > >> > What frequency are you running the kernel at ? I would suggest >> > 1024Hz. >> > >> > Rob >> > >> >> Hi, >> >> >> >> For some reason Seq24's timing isn't what it used to be on my >> >> computer... This is after a fresh install of Debian on a new hard >> >> drive, but I installed exactly the same kernel I had before. >> >> Realtime priority is working fine with Jack. I'm planning to do >> >> some research on this issue, but does anyone have any pointers to >> >> common causes of timing issues with ALSA MIDI or seq24 in >> >> particular? >> >> >> >> Thanks, >> >> Ben > >------------------------------------------------------------------------- >Using Tomcat but need to do more? Need to support web services, security? >Get stuff done quickly with pre-integrated technology to make your job easie= r >Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo >http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=3D120709&bid=3D263057&dat=3D12= 1642 >_______________________________________________ >seq24-users mailing list >seq...@li... >https://lists.sourceforge.net/lists/listinfo/seq24-users |