Re: lots of unplugged by timer normal or abnormal?

["Alan D. Brunelle" <Alan.Brunelle@hp.com>]

On Tue, 2009-10-06 at 11:53 -0700, Simon Kirby wrote:
> Hello,
> 
> I was just testing out blktrace/blkparse/btrace on a box that is hitting
> some performance walls, and noticed that there are a fair amonut of "UT"
> events (unplug by timer).  Is this normal/expected?  For example:
> 
> [sroot@nas04:/root]# btrace /dev/etherd/e7.0 | grep T
> 152,32   4     1379     3.582513494     0 UT   N [swapper] 8
> 152,32   1     1289     4.329760067     0 UT   N [swapper] 1
> 152,32   3     1132     4.362257911     0 UT   N [swapper] 3
> 152,32   7     1070     4.375258374     0 UT   N [swapper] 1
> 152,32   3     1146     4.382260172     0 UT   N [swapper] 5
> 152,32   1     1318     4.417759727  2830 UT   N [nfsd] 3
> 152,32   5     1003     4.498757105     0 UT   N [swapper] 1
> 152,32   1     1368     4.517761127     0 UT   N [swapper] 1
> 152,32   0     1133     4.585522116     0 UT   N [swapper] 5
> 
> This is on 2.6.30.5 with the 2.6.30.6 XFS patches.
> 
> Cheers,
> 
> Simon-

Hello Simon- 

This looks pretty bad - could you tell me what distro you are running on
as a base? And did this happen before 2.6.30.5 (the poor performance)?
And could you provide a more complete snippet of blktrace output
(showing a handful of complete ops)?

Thanks,
Alan D. Brunelle
Hewlett-Packard