Rosegarden - "System timer resolution is too low" - Mandrake

This is a discussion on Rosegarden - "System timer resolution is too low" - Mandrake ; Howdy, When I started up rosegarden4 (v. 1.2.3) that comes with Mandriva 2007.0 I got a warning about my system timer resolution being too low. I posted a question about this to the rosegarden-user mailing list and got this in ...

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Thread: Rosegarden - "System timer resolution is too low"

  1. Rosegarden - "System timer resolution is too low"

    Howdy,

    When I started up rosegarden4 (v. 1.2.3) that comes with Mandriva
    2007.0 I got a warning about my system timer resolution being
    too low. I posted a question about this to the rosegarden-user
    mailing list and got this in reply:

    Since 2.6.x the Linux kernel has been shipping with
    the default timer resolution set too [coarse] for MIDI
    purposes. This changed somewhere after 2.6.9, and the default
    went from 1000 Hz to 250 Hz. Everybody across the spectrum of
    distros is getting hit with this annoying problem.

    If your kernel is otherwise working, and if you can get a
    copy of its source and its config, all you have to do is
    change one configuration option and rebuild. The option is
    under Processor Type and Frequency -> System Timer, and you
    want to pick 1000 HZ, save the config, rebuild, and so forth.

    Another person on the list replied:

    One gets this same message on a vanilla OpenSuSE 10.2 machine
    (Rosegarden was unable to find a high-resolution timing
    source for MIDI performance...) You need to recompile your
    kernel with the system timer frequency parameter changed from
    the default 250 Hz to 1000Hz. There is a how-to here for
    SuSE, which may be helpful:
    http://wiki.jacklab.net/index.php/Ro...mer_resolution

    I know how to build and install kernels. But, when I do that then a
    number of things break because the kernel source name and module names
    of the subsequent kernel don't seem to match well enough for dkms (or
    whatever) to find the right stuff to load my proprietary video driver.
    On Mandrake 10.1 I lived without video hardware acceleration whenever I
    wanted to use my pro-audio applications. Yuck.

    Is there any real-time way to change the timer resolution?
    Should I be submitting this in Mandriva's bugzilla? I would think
    that this change might be easily bundled into the next kernel
    security release. Your thoughts?

    Thanks....

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  2. Re: Rosegarden - "System timer resolution is too low"

    On Wed, 24 Jan 2007 13:23:59 -0500, Kevin the Drummer wrote:

    > Is there any real-time way to change the timer resolution?


    See /usr/share/doc/kernel-doc-2.6.17.5mdv-1/rtc.txt
    Alter kernel version as appropriate. Install the kernel-doc
    if you haven't already.

    The file includes a sample program with the lines ...

    for a sample program (must be run as root), to alter
    the timing in the lines ...

    /* The frequencies 128Hz, 256Hz, ... 8192Hz are only allowed for root. */
    for (tmp=2; tmp<=64; tmp*=2) {
    retval = ioctl(fd, RTC_IRQP_SET, tmp);

    Regards, Dave Hodgins

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