Messages in this thread | | | From | Hal Wigoda <> | Subject | Re: Debugging kernel semaphore contention and priority inversion | Date | Thu, 18 Aug 2005 10:13:50 -0500 |
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will netconsole install on mandriva?
On Aug 18, 2005, at 9:50 AM, Davda, Bhavesh P ((Bhavesh)) wrote:
>> -----Original Message----- >> From: Mike Galbraith [mailto:efault@gmx.de] >> Sent: Wednesday, August 17, 2005 11:10 PM >> At 09:43 PM 8/17/2005 -0600, you wrote: >>>> >>>> Have you tried sysrq t? See the Documentation/sysrq.txt file. >>> >>> This is a headless system. >> >> You could try netconsole. > > Haven't heard of it before. Will look into it. But I doubt it will help > pinpoint the semaphore holder, if all I can do is sysrq stuff. > >> >>>> >>>> How stuck is the system? >>>> >>>> Keith >>> >>> Very. Only pingable, but can't login via >> telnet/ssh/anything. Reason is >>> the same reason the low priority mystery task is unable to run and >>> release the held semaphore. >> >> (hmm. I'm obviously missing some original context here) >> >> Sounds like there must be another player who is RT prio + spinning. >> >> -Mike > > Very good! Yes, I left out that piece of detail in my original posting. > There is a real low priority (4) SCHED_FIFO (hence still higher than > any > SCHED_OTHER) task spinning. But it is not the semaphore holder. I am > trying to identify which kernel thread (because that's most likely) > running at SCHED_OTHER real low priority (too nice) is holding the > semaphore, locking out a priority 50 SCHED_FIFO task in its sys_write() > as a result. > > Thanks > > - Bhavesh > > Bhavesh P. Davda | Distinguished Member of Technical Staff | Avaya | > 1300 West 120th Avenue | B3-B03 | Westminster, CO 80234 | U.S.A. | > Voice/Fax: 303.538.4438 | bhavesh@avaya.com > - > 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/ >
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