Re: Strange vmstat output. 2.6.10 Scheduler?

[Jens Axboe]

On Tue, Feb 01 2005, Catalin(ux aka Dino) BOIE wrote:
> Hello!
> 
> I have a weird problem with a server. I use deadline.
> The output of vmstat is:
>  1  1  12312   6064   7580 815432    0    0  5332   456 1263  3119 22  5  0 
>  73
>  0  1  12312   5280   7584 816240    0    0  6204   620 1307  1530 15  4  0 
>  81
>  0  1  12312   6096   7528 815088    0    0  7604  8732 1256  1398  5  8  0 
>  87
>  0  1  12312   6048   7528 815144    0    0     8     8 1243  1440 14  2  0 
>  84
>  0  1  12312   6048   7528 815168    0    0     0     0 1261  1287  8  2  0 
>  90
>  0  2  12312   6040   7584 815184    0    0     0     0 1258  1197  7  2  0 
>  91
>  0  2  12312   6024   7584 815208    0    0     0     0 1265  1309  6  5  0 
>  89
>  0  2  12312   6024   7584 815208    0    0     0   136 1253   365  2  2  0 
>  96
>  0  2  12312   5984   7584 815208    0    0     0     0 1268   413  2  1  0 
>  97
>  0  2  12312   6052   7584 815208    0    0     0     0 1270   375  2  1  0 
>  97
>  1  0  12312   6164   7584 815156    0    0  6188   288 1270  4314 23  5  0 
>  72
>  0  1  12312   5684   7536 815592    0    0  4128  8656 1270  1316 14  3  0 
>  83
>  0  1  12312   5684   7536 815608    0    0     0     0 1258  1251  8  3  0 
>  89
>  0  1  12312   5552   7536 815628    0    0     0     0 1258  1327  8  2  0 
>  90
>  0  1  12312   5552   7536 815644    0    0     0     0 1264  1127  7  2  0 
>  91
>  0  1  12312   5552   7536 815668    0    0     0     2 1258  1225  8  3  0 
>  89
>  0  3  12312   5248   7588 816108    0    0  4340   585 1249  1316  7  3  0 
>  90
>  0  2  12312   5612   7584 815680    0    0  3092   188 1254   411  3  1  0 
>  96
>  0  2  12312   5564   7584 815676    0    0     0     0 1261   259  2  2  0 
>  96
>  0  2  12312   5564   7584 815676    0    0     0     0 1254   348  2  1  0 
>  97
> 
> It seems strange because iowait is at 90% but nothing is trasnfered 
> to/from disk. Why is that?

The bi/bo numbers are sometimes a little confusing, it doesn't mean that
the drive is actually doing 8656kb of io at that very second - only that
this much io was queued to the drive.

> I run postgresql on this server and I'm not satistied by it's speed.
> 
> Single Pentium IV, IDE disk.
> 
> What can be the problem?

Do you have write cache enabled on the drive?

-- 
Jens Axboe

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