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* 2.6.9: unkillable processes during heavy IO
@ 2004-11-14 22:15 Brad Fitzpatrick
  2004-11-14 21:41 ` Alan Cox
                   ` (3 more replies)
  0 siblings, 4 replies; 11+ messages in thread
From: Brad Fitzpatrick @ 2004-11-14 22:15 UTC (permalink / raw)
  To: linux-kernel

We have two database servers which freeze up during heavy IO load.  The
machines themselves are responsible, but the mysqld processes are forever
locked, unkillable with even kill -9.  I can't restart with MySQL without
rebooting the machines.

I can reasonable rule out hardware, since this is happening in the
same way on two identical machines.

I'd like to know how I can debug this, to file a proper bug report.

The hardware/software stack is:

  - Dual Opteron 246, SMP kernel, w/ NUMA
  - 9 GB of memory (4GB in one zone, 5GB in the other)
  - MySQL, running mostly InnoDB, but some MyISAM
  - MegaRAID raid-10
  - device mapper
  - XFS (used as both O_DIRECT from InnoDB and regularly from MyISAM)

At this point I'm going to try changing different variables on
different machines in order to try and isolate it, but it's a slow
process.

  - on raw partions, instead of device mapper
  - ext3 instead of XFS
  - not using O_DIRECT

"Screenshot":

roast:~# killall -9 mysqld
roast:~# killall -9 mysqld
roast:~# ps afx | grep mysqld
31495 ?        D      0:08 /usr/local/mysql/bin/mysqld --defaults-extra-file=/usr/local/mysql/data/my.cnf --basedir=/usr/local/mysql/ --datadir=/data/mydb --user=root
--pid-file=/var/run/mysqld/mysqld.pid --skip-locking --port=3306 --socket=/var/run/mysqld/mysqld.sock
32391 ?        D      0:01 /usr/local/mysql/bin/mysqld --defaults-extra-file=/usr/local/mysql/data/my.cnf --basedir=/usr/local/mysql/ --datadir=/data/mydb --user=root
--pid-file=/var/run/mysqld/mysqld.pid --skip-locking --port=3306 --socket=/var/run/mysqld/mysqld.sock
  515 ?        D      0:00 /usr/local/mysql/bin/mysqld --defaults-extra-file=/usr/local/mysql/data/my.cnf --basedir=/usr/local/mysql/ --datadir=/data/mydb --user=root
--pid-file=/var/run/mysqld/mysqld.pid --skip-locking --port=3306 --socket=/var/run/mysqld/mysqld.sock
  517 ?        Z      0:00  \_ [mysqld] <defunct>

Next time it hangs like this, how can I get a kernel backtrace or other useful information
for a certain process?

Thanks!

- Brad


^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2004-11-19  6:02 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2004-11-14 22:15 2.6.9: unkillable processes during heavy IO Brad Fitzpatrick
2004-11-14 21:41 ` Alan Cox
2004-11-14 22:30 ` Andrew Morton
2004-11-14 22:45   ` Andries Brouwer
2004-11-15  7:39 ` Lenar Lõhmus
2004-11-16 13:56 ` Brad Fitzpatrick
2004-11-17  4:01   ` Andrew Morton
2004-11-17  4:55     ` Nathan Scott
2004-11-17  7:00       ` Brad Fitzpatrick
2004-11-18  5:05         ` Nathan Scott
2004-11-19  4:59           ` Nathan Scott

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