Re: ext3 IO latency measurements (was: Linux 2.6.29)

Ingo Molnar
2009-03-26T09:10:40Z

* Ingo Molnar <mingo@elte.hu> wrote:

> Oh, and while at it - also a job control complaint. I tried to
> Ctrl-C the above script:
>
> file # 858 (253560 bytes), reading it took: 0.06 seconds.
> file # 859 (253560 bytes), reading it took: 0.02 seconds.
> file # 860 (253560 bytes), reading it took: 5.53 seconds.
> file # 861 (253560 bytes), reading it took: 3.70 seconds.
> file # 862 (253560 bytes), reading it took: 0.88 seconds.
> file # 863 (253560 bytes), reading it took: 0.04 seconds.
> file # 864 (253560 bytes), reading it took: ^C0.69 seconds.
> file # 865 (253560 bytes), reading it took: ^C0.49 seconds.
> file # 866 (253560 bytes), reading it took: ^C0.01 seconds.
> file # 867 (253560 bytes), reading it took: ^C0.02 seconds.
> file # 868 (253560 bytes), reading it took: ^C^C0.01 seconds.
> file # 869 (253560 bytes), reading it took: ^C^C0.04 seconds.
> file # 870 (253560 bytes), reading it took: ^C^C^C0.03 seconds.
> file # 871 (253560 bytes), reading it took: ^C0.02 seconds.
> file # 872 (253560 bytes), reading it took: ^C^C0.02 seconds.
> file # 873 (253560 bytes), reading it took:
> ^C^C^C^Caldebaran:~/linux/linux/test-files/src>
>
> I had to hit Ctrl-C numerous times before Bash would honor it.
> This to is a very common thing on large SMP systems. [...]

It happened when i tried to Ctrl-C the compile job as well:

Thu Mar 26 11:04:05 CET 2009
Thu Mar 26 11:06:30 CET 2009
^CThu Mar 26 11:07:55 CET 2009
^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^C^Caldebaran:/home/mingo/linux/linux>

a single Ctrl-C is rarely enough to stop busy Bash shell scripts on
Linux. Why?

Ingo