Geert Hendrickx wrote:

>>>I often see my X server completely freeze for 10 seconds or more when
>>>doing a cvs up, or untarring a large file.  I notice this problem
>>>especially on machines with a lot (1Gb) of RAM.  Is this
>>>normal/acceptable, or a known problem, or just a matter of tuning
>>>things here?
>>
>>Tuning... This has been up before. The default tuning allows too much
>>memory be used for disk buffers and disk cache, making applications (such
>>as X) suffer.
> 
> So what should I do about it?  Some sysctls to mess with?  
> And then why do I experience this problem the most on high-memory machines?  

I have seen the same issue pop up on FreeBSD 5.x a while ago, and it has
been fixed in the meantime. There it was an issue with flushing buffer
queues in a suboptimal way. I also experienced it more on faster
machines with larger memory sizes, so the symptoms are similar to the
ones you describe. Now, even though the underlying VM architecture is
different in Net- and FreeBSD, I would think that the problem might be
similar. Perhaps the kernel is flushing too large pieces at a time,
simply starving the scheduling of user processes during that time.

mkb.