Re: Real-time pre-emption kswapd/kscand questions

From: Michael Blanc (mblanc_at_znet.com)
Date: 11/29/04

  • Next message: Roger Leigh: "Re: wcsftime output encoding" 
    Date: Mon, 29 Nov 2004 11:36:01 -0800

    Hello Tom,

    The FDDI controller may well be the key to the problem here. If there is
    traffic on the line which generates an interrupt signal, then the service of
    that interrupt might be sufficient to cause a small gap in the analog data
    acquisition (though ~24 ms sounds excessive!). Anyways it would scarcely
    matter at what priority a request gets scheduled which emmanates from the
    transaction (of course if posting the request itself generates a pass
    through the task scheduler, there goes some more of the 24 ms....).

    A crude, though possibly effective method would be to disable the interrupt
    on the FDDI before the 60 sec of data acq initiates, then re-enable it
    after. Ofcourse, since you probably have "all the time in the world" before
    onset, and after cessation of that 60 sec period, you could do something
    more "formal" with LINUX.

    Please let me know how this works out, either on this forum by the email.

    Cordially,

    M. Blanc

    Tom wrote in message <1e7d6669.0411290650.378632f4@posting.google.com>...
    >HI Michael,
    >
    >
    >Sorry for the response delay. Soon after my post, I was away on
    >holiday.
    >
    >You raise a valid issue. Yes, the ethernet is enabled during
    >acquisition and sends occasional status messages back to a remote host
    >controlling the acqusition, however, from a lower priority thread.
    >
    >This has raised my suspicions also. I am working on a method to
    >disable the status messages during acquisition to verfiy whether this
    >is a culprit.
    >
    >Thanks for your post. Sorry for the delay in responding.
    >
    >Tom
    >
    >
    >
    >
    >"Michael Blanc" <mblanc@znet.com> wrote in message
    news:<1101057980.250649@news-1.nethere.net>...
    >> Is there an ethernet controller installed on your system, (and enabled
    >> during data acquisition)?

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