RE: Kernel 2.6.8.1: swap storm of death - CFQ scheduler=culprit

Karl Vogel
2004-08-24T10:28:08Z

> > > Original post with testcase + stats:
> > > http://article.gmane.org/gmane.linux.kernel/228156
> >
> > 2.6.8.1-mm4 clean does not reproduce the problem. Marcelo, your
> > 2.6.8-rc4 report is not valid due to the fixed problem
> related to that
> > in CFQ already. I'd still like for you to retest with 2.6.8.1.
> >

Did some extra testing yesterday. When not running X or anything
substantial, I'm able to trigger it after running the expunge 2 or
3 times in a row.
If I increase the calloc size, it triggers faster (tried with 1Gb
calloc on a 512Mb box with 1Gb swap partition).

The first expunge run, completes fine. The ones after that, get
OOM killed and I get a printk about page allocation order 0 failure.

The 2.6.8.1-mm4 was a clean version, but I will double check this,
this evening.

I also tried with deadline, but was unable to trigger it.

> Oh, and please do also do a sysrq-t from a hung box and save
> the output.

Note: the box doesn't hang completely. Just some processes get stuck
in 'D' and the machine swaps heavily.

The tests of yesterday evening, did recover. So I'm guessing if I had
waited long enough the box would have recovered on the previous
tests. Looking at the vmstat from my previous tests, shows that the
box was low on memory (free/buff/cache are all very low):

http://users.telenet.be/kvogel/vmstat-after-kill.txt

That was probably why it was swapping like mad.

Will provide you with that sysrq-t this evening.

Karl.