Re: Odd slow-down issue

["Steven M. Bellovin" <smb%cs.columbia.edu@localhost>]

On Wed, 12 Mar 2008 14:13:40 -0500
Michael Graff <michael_graff%isc.org@localhost> wrote:

> I have seen this four times now.  Once on a "server" (intel
> dual-core, no X11 running but it does have a built-in VGA, mostly
> unused) and three times on my laptop.
> 
> Symptoms are things like "sleep 1" taking a variable number of 
> seconds.  "systat vmstat 1" will update once every 5-10 seconds or
> so.  On the laptop, all disk I/O seems to stop, the cursor does not
> move but jumps, and while the windows are responsive, the "focus
> under cursor" does not cause the actual window highlight to change as
> it should.
> 
> Typing takes 3-5 seconds to appear, and then does so in batches.
> Mistyping a command means that window is dead.  Starting any
> application like "systat" takes up to 30 seconds.
> 
> These systems have completely different SMP (laptop is 1-core, server
> is 2-core), graphics, network cards, etc.  The only commonality is
> that each is running NetBSD, and SEEMS to be triggered by high CPU or
> disk load.  I cannot recreate it on demand.
> 

I haven't seen that, but I upgraded my kernel and xorg on my laptop a
week ago (before that, I'd been running a Feb 9 kernel) and since then
I've been quite unhappy with responsiveness.  When I can see text
rendering, on a fast machine, something's wrong.  And there's a
noticeable lag between when I type a character (especially into my
mailer) and when I see the echo.  It's not quite the same as what
you're seeing, but I've been wondering about scheduler changes.


                --Steve Bellovin, http://www.cs.columbia.edu/~smb