Messages in this thread | | | Subject | Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4] | From | Thomas Gleixner <> | Date | Mon, 01 Nov 2004 18:58:22 +0100 |
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On Mon, 2004-11-01 at 12:55 -0500, Lee Revell wrote: > I think there might even be a _very_ rare errant irq disable in T3 even. > On my 2-day test runs with 100s of millions of samples, I got 2 or 3 > outliers in each graph. Jow Gwinn from LKML (thanks Joe) ran a > statistical analysis that showed these to be independent from the 4 or 5 > underlying exponential distributions (each corresponding to a known or > suspected nonpreemptible section). Our theory was that these were very > rare code paths or race conditions that left IRQs off. Unfortunately > this seems impossible to debug unless you have a way to make the machine > crash dump immediately when it detects the situation. > > Anyway, the clearest way to demonstrate the problem with the -V series > here is to run the version of Florian's tool that tells you how many > interrupts were missed. If I spin my (USB, not sharing irq with > soundcard) trackball as fast as I can I can get it up to 54 or 55 in a > row. If I move it just the right way I can see the humps appear - 2, > then 15, then 50 then 15 then 2 missed interrupts in a row. This is at > 1024Hz - at 2048 I can get it to miss several hundred IRQs, but this > inevitably locks the machine. > > I suspect the lockups and the latencies are same bug.
Until now there was no output on lockup. No I got one. The command was: cat /proc/interrupts
Hope that helps
tglx
cat/1488: BUG in down_mutex at /work/thomas/Linux/2.6.9-mm1-RT/lib/rwsem-generic.c:1059 [<c01ca9e2>] down_mutex+0x72/0x80 (8) [<c012db9a>] __mutex_lock+0x2a/0x40 (36) [<c012dbc7>] _mutex_lock+0x17/0x20 (12) [<c013fd62>] kfree+0x52/0xf0 (8) [<c013fd62>] kfree+0x52/0xf0 (4) [<c01774a2>] single_release+0x32/0x40 (32) [<c01571ba>] __fput+0x13a/0x150 (20) [<c0155899>] filp_close+0x59/0x90 (32) [<c015593f>] sys_close+0x6f/0xa0 (24) [<c010603b>] syscall_call+0x7/0xb (28)
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