Subject: Re: Jerky/frozen mouse under load
To: None <>
From: Jakub Misak <>
List: netbsd-users
Date: 02/13/2005 16:57:24
Thank you for your advice and suggestions. wrote:

> OK try the following things to improve your system's performance:
> 1) Mount ffs filesystems (/, /usr, /var) with softdep option, i.e. edit 
> your /etc/fstab e.g.
> /dev/wd0a / ffs rw,softdep 1 1
> This will mount root filesystem and enable softdep on it

I think softdep was already enabled (by default?)... It was there already.

> 2) Build custom kernel with optimisations.
> ...

OK. I did it, with the options your suggested.

I think it's a bit better now. Not too much, I'm not quite sure... It's 
hard to say.

But what's interesting is that with HZ=1000, things are now much more 
CPU-hungry. This is the effect that I noticed in Linux 2.6,too when they 
switched to 1000 Hz from 100 in 2.4 - even though they said that the 
overhead of 1000 HZ shoud be negligible. Basic tasks now eat much more 
CPU (if the CPU meters are correct). Keyboard input - when I press a key 
in a text editor and hold it with autorepeat, the CPU used to stay more 
or less at 0 % with 100 Hz. But with 1000 Hz, it is now 20-30 %. Or even 
if I type something quickly. Or cycle through the GUI widgets, using a 
keyboard with autorepeat, again it's 0-1 % (100 Hz) vs. 20 % (1000)... 
Why is that? Is the CPU meter wrong? Is the overhead of 1000 Hz really 
so drastic?