A version of preempt-stats for the 2.5 series kernel is available at:
ftp://ftp.kernel.org/pub/linux/kernel/people/rml/preempt-stats
and your favorite mirror. Patches for 2.4 are available, too.
This patch, used on top of preempt-kernel, allows the measuring of
periods of non-preemptible so that we can identify long-held locks. The
patch creates a proc entry, latencytimes, which contains the top 20
worst-case recorded periods since it was last read. To begin recording,
read the file once. Subsequent reads will return the results. I.e.,
[23:25:08]rml@langston:~$ cat /proc/latencytimes
Worst 20 latency times of 277 measured in this period.
usec cause mask start line/file address end line/file
9982 spin_lock 0 488/sched.c c0117ee2 645/irq.c
968 BKL 0 666/tty_io.c c0193d58 645/irq.c
430 spin_lock 0 69/i387.c c010f34f 96/mmx.c
103 ide0 0 583/irq.c c010ab1c 645/irq.c
100 BKL 0 2562/buffer.c c014abda 2565/buffer.c
54 BKL 0 702/tty_io.c c019406b 704/tty_io.c
... etc
The goal would be to identity the problem areas and fix them.
Robert Love
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This archive was generated by hypermail 2b29 : Tue Jan 15 2002 - 21:00:43 EST