XFS hung on 2.6.33.3 kernel

[Ilia Mirkin]

On Thu, Aug 5, 2010 at 2:25 AM, Dave Chinner <david at fromorbit.com> wrote:
> a couple of things to see if the hang can be caused faster? Maybe
> trying these different initial conditions:

Together or independently?

>
>        - use a smaller test file

OK. My theory [based on no evidence] was that it had to be bigger than
RAM size. I'll try less though.

>        - allocate the file with worst case fragmentation by
>          writing it backwards in synchronous 4k blocks before
>          running the test

I created the file with

dd if=/dev/zero of=... bs=1M count=...

How would I "write backwards"? Like truncate and then seek to the end,
write, seek back, write, etc? Is there a utility that might do it
already?

>        - preallocating the test file with fallocate()

Sure.

>
> Also, it woul dbe interesting to find out if a newer kernel also
> hangs in a similar manner, say 2.6.35?

Will do.

-- 
Ilia Mirkin
imirkin at alum.mit.edu