System extremely slow under light load

[Ronald Klop]

On Wed, 13 Apr 2011 14:28:03 +0200, Bartosz Fabianowski  
<freebsd at chillt.de> wrote:

> Hi list
>
> I am having problems with my 8.2-STABLE laptop. At times, even a very  
> light load makes the system grind to a halt. Once an application is in  
> the foreground, I can interact with it just fine. But when I click on a  
> long-unused menu item or try to switch applications, I have to wait  
> dozens of seconds or even minutes. It feels as if things were being  
> swapped in very slowly. However, top says otherwise:
>
> The box has 4 GB of RAM with only 680 MB used. On top of that, 69 MB of  
> swap are in used. That last number does not seem to be changing, so  
> nothing is being swapped in or out.
>
> The load that seems to cause the worst problems is an import of  
> OpenStreetMap data into a PostgreSQL 9 database. This does not exercise  
> the CPU (a Core i7 Quad) much as CPU load hovers around the 20% mark  
> most of the time and powerd is happy to reduce the operating frequency  
> down to a few hundred MHz. There also does not seem to be much disk  
> activity.
>
> So, memory, CPU and disk all seem fine. And still, whenever I try to  
> switch applications, I have to wait minutes for them to appear. I am  
> having a hard time figuring out what is going on. Any tips would be  
> greatly appreciated.
>
> I am including the outputs of vmstat -c 2 and iostat -c 2 in the hope  
> that these may shed some light on this.
>
> Thanks,
> - Bartosz Fabianowski
>
>
> vmstat -c 2
>   procs      memory      page                    disks     faults    cpu
>   r b w     avm    fre   flt  re  pi  po    fr  sr ad0 cd0   in   sy cs  
> us sy id
>   0 1 20  21376M   203M  1652   2   1   1  2993 289   0   0   90  949  
> 2764  5  2 93
>   0 0 20  21378M   197M  1332   0   5   1  2165   0  58   0  208 7875  
> 3614  2  2 96
>
>
> iostat -c 2
>         tty            ada0              cd0            pass0    cpu
>   tin  tout  KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s  us ni sy  
> in id
>   188  2367 51.73  22  1.12   0.00   0  0.00   0.00   0  0.00   3  1  2  
>   0 93
>     1   991 18.06  49  0.86   0.00   0  0.00   0.00   0  0.00   3  0  2  
>   0 94
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Just for an experiment, try to disable powerd and look if things improve.

Ronald.