lkml.org 
[lkml]   [2004]   [Dec]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: USB making time drift [was Re: dynamic-hz]
    Date
    On Wednesday 15 December 2004 04:17, Andrea Arcangeli wrote:
    >On Tue, Dec 14, 2004 at 09:59:23PM -0500, Gene Heskett wrote:
    >> Which way? I was running quite fast here, several minutes an
    >
    >In the future, if I disable the logic it goes in the past at the
    > same speed it was previously going in the future.
    >
    >> hour, then I discovered the tickadj command, found its default
    >> was 10000, and started reducing it. At 9926, I'm staying within
    >> a sec an hour now. I have no idea when this started, I didn't
    >
    >That seems quite an hack, note I did an hack too and it make the
    > drift much smaller (it gets manageable). But our modifications are
    > wrong.
    >
    >The point is that this didn't happen with HZ=100, so it's not that
    >tickadj is wrong, it's the tick adjustment code that doesn't work.
    >
    The HZ=1000 is the culprit?

    >You may want to recompile your kernel with HZ=100 and verify it goes
    >away (I didn't verify myself, but I verified the max irq latency I
    > get is 4msec, and in turn I'm sure HZ=100 would fix it

    Humm, that might also reduce the obviousness of the irq activity in
    the audio, there are times when I can hear it very plainly while a
    low level audio src is in use, like the sub-millivolt levels that come
    out of my Hauppauge WinTV-GO+FM card. I keep having to turn the
    master down to almost zip in order to keep it from sounding like I
    have mice chewing in the walls, but its coming from the speakers.
    Onboard AC-97 audio of course. Crappy stuff... Humm, 100HZ would
    translate to 10 millisecond intervals. If you had a 4 millisecond
    latency,
    that would be spread over 4 of the 1000 hz interrupts. That sounds
    rather confusing to the service routine I imagine.

    I'll do that just for grins & report back.

    --
    Cheers, Gene
    "There are four boxes to be used in defense of liberty:
    soap, ballot, jury, and ammo. Please use in that order."
    -Ed Howdershelt (Author)
    99.30% setiathome rank, not too shabby for a WV hillbilly
    Yahoo.com attorneys please note, additions to this message
    by Gene Heskett are:
    Copyright 2004 by Maurice Eugene Heskett, all rights reserved.

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 14:08    [W:0.027 / U:28.708 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site