Interrupt latency problems

[Craig Boston]

On Saturday 10 May 2003 07:37 am, Paul Richards wrote:
> I'm having real problems with current with heavy disk activity.
>
> When working in X and updating ports which causes a lot of disk activity
> I get *very* poor interactive responses. Keypresses can not appear for
> seconds and mouse movement is very jerky and unresponsive.

Can you watch top or gkrellm or something to see if any swapping is occurring 
during the times when it's unresponsive?  It may be hard to get stats out of 
top while it's frozen, but you might be able to see if any processes in 
sbwait or a similar status.

Sometimes I have very similar symptoms that I THINK are the result of X 
getting swapped out.  On my machine, X likes to grow to outrageous memory 
sizes (300M+) and because it's so big parts of it get swapped out when 
there's memory pressure.

Sometimes, especially during heavy disk activity and almost always if 
something's both disk and RAM intensive (like cvsup), the system will become 
almost totally unresponsive for up to 30 seconds.  Mouse lags, keyboard input 
not showing up, windows not becoming focused when I move the mouse over them, 
etc.  From what I can tell it looks like X is desperately trying to access 
parts of it that are swapped to disk and is competing with the disk-intensive 
process trying to read its pages in, causing bad disk thrashing...  I usually 
have to restart X every few days to keep it from getting too big.  This 
happens to me even with backing store and save-unders both DISABLED.

Your problem may caused by something completely different, but the symptoms do 
seem quite similar.

Craig