Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]

From: Florian Schmidt (mista.tapas_at_gmx.net)
Date: 10/31/04

  • Next message: Dmitry Torokhov: "Re: [PATCH] Configurable Magic Sysrq" 
    Date:	Sun, 31 Oct 2004 20:06:21 +0100
To: Florian Schmidt <mista.tapas@gmx.net>

    On Sun, 31 Oct 2004 16:59:13 +0100
    Florian Schmidt <mista.tapas@gmx.net> wrote:

    > p.s. new rtc_wakeup version uploaded, which shows the percentage converted
    > to usecs (always positive, you need the sign?). btw: with V0.6.2 i sometimes
    > see jitter > 100% but still no lost irq (/dev/rtc still reports only 1
    > delivered irq on next wakeup). I cannot provke lost irqs with -f up to 2048.
    > With -f 8192 i do get lost irq's [not amazing though].

    another update upped. small bugfix (still depended on jack, should work now
    w/o jack installed) plus minor cosmetic corrections. Here's example output
    for 2.6.8.1-P9 (under heavy load (multiple finds plus kernel compile plus UI
    artistics):

    ~/source/my_projects/rtc_wakeup$ ./rtc_wakeup
    rtc_wakeup - press ctrl-c to stop
    freq: 1024
    max # of irqs: 0 (run until stopped)
    jitter threshold: 5% (48 usec)
    output filename: /dev/null
    rt priority: 90(91)
    getting cpu speed
    1194913254.155 Hz (1194.913 MHz)
    # of cycles for "perfect" period: 1166907 (976 usec)
    setting up ringbuffer
    setting up consumer thread
    setting up /dev/rtc
    locking memory
    turning irq on, beginning measurement
    new max. jitter: 1.6% (15 usec)
    new max. jitter: 1.9% (18 usec)
    new max. jitter: 2.6% (25 usec)
    new max. jitter: 2.9% (28 usec)
    new max. jitter: 3.2% (31 usec)
    new max. jitter: 3.3% (31 usec)
    new max. jitter: 3.3% (32 usec)
    new max. jitter: 3.5% (34 usec)
    new max. jitter: 3.5% (34 usec)
    new max. jitter: 3.7% (35 usec)
    new max. jitter: 4.3% (41 usec)
    new max. jitter: 4.9% (47 usec)
    threshold violated: 5.6% (54usec)
    new max. jitter: 5.6% (54 usec)
    threshold violated: 5.3% (51usec)
    done.
    total # of irqs: 168072
    missed irqs: 0
    threshold violations: 2
    max jitter: 5.6% (54 usec)

    So basically like lee said, 7% seems to be a normal upper limit for VP
    boxes (there might be spikes though).

    V0.6.2 looked good, too, until it locked up again (under heavy load with
    rtc_wakeup running) ;) Will build one with debugging enabled tomorrow.

    flo
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