Re: Sudden "hangs"....

Satoru Takeuchi
2010-09-16T23:57:25Z

Hi,

(2010/09/16 23:33), Rogier Wolff wrote:
>
> Hi,
>
> It seems my home workstation hangs on a "mkdir" once every morning for
> about half a minute. It'll freeze whatever I'm doing and continue
> happily 30 seconds later, but I can't figure out what's going on
> because it's frozen...
>
> My server did it just now and I was able to grab some more
> debugging info.....
>
> obelix:~> time mkdir /recover3/testdir
> 0.000u 0.004s 2:11.83 0.0% 0+0k 0+0io 5pf+0w
> obelix:~>
>
> Over two minutes to make a directory! (I have the impression that
> the wait is for something to finish, so if I had started the mkdir
> a minute earlier, it would've taken a minute longer).
>
> The process:
> 28649 root 20 0 0 0 0 D 6.3 0.0 0:11.69 flush-9:0
>
> was in "top", and as shown here in "disk wait" mode.
>
> While this is going on, "vmstat 1" shows:
>
> procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy id wa
> 0 1 5368 12764 324804 1616932 0 0 464 0 244 477 0 2 0 98
> 0 1 5368 12764 324556 1617168 0 0 448 0 255 474 0 1 0 99
> 0 1 5368 12764 324952 1616832 0 0 472 0 257 487 0 1 0 99

It seems normal data. I suggest you to do the check dmesg and
iostat to confirm whether something wrong is occuring on your
disk which you issued mkdir.

Thanks,
Satoru

>
> ... about 400 kbytes of IO per second. This is similar to the
> single-disk machine at home.
>
> The server runs:
>
> Linux version 2.6.34 (wolff@abra2) (gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)) #5 SMP Tue Jun 1 14:44:01 CEST 2010
>
> at home I run:
> Linux version 2.6.28-19-generic (buildd@palmer) (gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4) ) #61-Ubuntu SMP Wed May 26 23:35:15 UTC 2010
>
>
> Does anybody know what's going on?
>
> Roger.
>
>