Re: Fio rbd stalls during 4M reads

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FWIW the specific fio read problem appears to have started after 0.86 and before commit 42bcabf.

Mark

On 10/24/2014 12:56 PM, Gregory Farnum wrote:
There's an issue in master branch temporarily that makes rbd reads
greater than the cache size hang (if the cache was on). This might be
that. (Jason is working on it: http://tracker.ceph.com/issues/9854)
-Greg
Software Engineer #42 @ http://inktank.com | http://ceph.com


On Thu, Oct 23, 2014 at 5:09 PM, Mark Kirkwood
<mark.kirkwood@xxxxxxxxxxxxxxx> wrote:
I'm doing some fio tests on Giant using fio rbd driver to measure
performance on a new ceph cluster.

However with block sizes > 1M (initially noticed with 4M) I am seeing
absolutely no IOPS for *reads* - and the fio process becomes non
interrupteable (needs kill -9):

$ ceph -v
ceph version 0.86-467-g317b83d (317b83dddd1a917f70838870b31931a79bdd4dd0)

$ fio --version
fio-2.1.11-20-g9a44

$ fio read-busted.fio
env-read-4M: (g=0): rw=read, bs=4M-4M/4M-4M/4M-4M, ioengine=rbd, iodepth=32
fio-2.1.11-20-g9a44
Starting 1 process
rbd engine: RBD version: 0.1.8
Jobs: 1 (f=1): [R(1)] [inf% done] [0KB/0KB/0KB /s] [0/0/0 iops] [eta
1158050441d:06h:58m:03s]

This appears to be a pure fio rbd driver issue, as I can attach the relevant
rbd volume to a vm and dd from it using 4M blocks no problem.

Any ideas?

Cheers

Mark

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