31 Mar
2020
31 Mar
'20
1:44 p.m.
Hi Robert,
I have some interest in this area. I noticed that the kernel client was
performing poorly with sequential reads while testing the io500
benchmark a couple of months ago. I ended up writing a libcephfs
backend for ior/mdtest so we could run io500 directly with libcephfs
which ended performing similarly in most tests and significantly faster
for sequential reads. Ilya and I have done some work since then trying
to debug why the kernel client is slow in this case and all we've been
able to track down so far is that it may be related to aggregate iodepth
with fewer than expected kworker threads doing work. Next step is
probably to try and look at kernel lock statistics.
In any event, I would very much like to get a generic fast userland
client implementation working. FWIW you can see my PR for mdtest/ior here:
https://github.com/hpc/ior/pull/217
Mark
On 3/30/20 12:14 AM, Robert LeBlanc wrote:
On Sun, Mar 29, 2020 at 7:35 PM Yan, Zheng
<ukernel(a)gmail.com
<mailto:ukernel@gmail.com>> wrote:
On Mon, Mar 30, 2020 at 5:38 AM Robert LeBlanc
<robert(a)leblancnet.us <mailto:robert@leblancnet.us>> wrote:
do they mention which improvement?
I think it was in regards to removing some serial code paths. I don't
know if it was async work or parallel thread work. And recent as in
like 4.9 recent.
----------------
Robert LeBlanc
PGP Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1
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We have been evaluating other cluster storage solutions and one
of them is
just about as fast as Ceph, but only uses FUSE. They
mentioned that recent improvement in the FUSE code allows for
similar performance to kernel code. So, I'm doing some tests
between CephFS kernel and FUSE and that is not true in the Ceph case.