lkml.org 
[lkml]   [2002]   [Jan]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] update: preemptive kernel for O(1) sched
From
Date
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


-
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/

\
 
 \ /
  Last update: 2005-03-22 13:15    [W:0.053 / U:0.712 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site