kern/104624: Sound, mouse and keyboard badly interrupted while I/O (disk, net)

[Bruce Cran]

On Sun, 12 Dec 2010 12:19:23 +0000
Alexander Best <arundel at freebsd.org> wrote:

> On Sun Dec 12 10, Bruce Cran wrote:
> > On Sun, 12 Dec 2010 11:10:11 GMT
> > Alexander Best <arundel at freebsd.org> wrote:
> > 
> > >  i can confirm that a similar issue exists for me running a very
> > > recent HEAD snapshot on amd64. when the disk is performing heavy
> > > i/o (make -j8 buildworld e.g.) sound starts stuttering and the
> > > system goes semi-responsive. mostly the mouse input (usb) is
> > > lagging, but sometimes the cursor freezes in it's current
> > > position for 10 seconds or so. 
> > 
> > There was a discussion recently where we noticed this problem
> > appeared to occur mostly on systems with Intel Core 2 Duo CPUs.
> > I've seen a login paused for over 5 seconds (between typing the
> > password and the motd being displayed) due to an "svn up" on my
> > laptop for example.

A good way of triggering this seems to be running sysutils/fio with the
configuration:

[global]
size=512m
bsrange=4k-4k
numjobs=4

[f1]
rw=write

[f2]
stonewall
rw=randwrite

[f3]
stonewall
rw=read

[f4]
stonewall
rw=randread

It seems that about half-way through even fio stops doing any IO and
doing an "ls" takes a couple of seconds.

-- 
Bruce Cran