On Sat, 29 Dec 2007, Dan Williams wrote:

On Dec 29, 2007 9:48 AM, dean gaudet [off-list ref] wrote:

quoted

hmm bummer, i'm doing another test (rsync 3.5M inodes from another box) on
the same 64k chunk array and had raised the stripe_cache_size to 1024...
and got a hang.  this time i grabbed stripe_cache_active before bumping
the size again -- it was only 905 active.  as i recall the bug we were
debugging a year+ ago the active was at the size when it would hang.  so
this is probably something new.

I believe I am seeing the same issue and am trying to track down
whether XFS is doing something unexpected, i.e. I have not been able
to reproduce the problem with EXT3.  MD tries to increase throughput
by letting some stripe work build up in batches.  It looks like every
time your system has hung it has been in the 'inactive_blocked' state
i.e. > 3/4 of stripes active.  This state should automatically
clear...

cool, glad you can reproduce it :)

i have a bit more data... i'm seeing the same problem on debian's 
2.6.22-3-amd64 kernel, so it's not new in 2.6.24.

i'm doing some more isolation but just grabbing kernels i have precompiled 
so far -- a 2.6.19.7 kernel doesn't show the problem, and early 
indications are a 2.6.21.7 kernel also doesn't have the problem but i'm 
giving it longer to show its head.

i'll try a stock 2.6.22 next depending on how the 2.6.21 test goes, just 
so we get the debian patches out of the way.

i was tempted to blame async api because it's newish :)  but according to 
the dmesg output it doesn't appear the 2.6.22-3-amd64 kernel used async 
API, and it still hung, so async is probably not to blame.

anyhow the test case i'm using is the dma_thrasher script i attached... it 
takes about an hour to give me confidence there's no problems so this will 
take a while.

-dean