Dear Ilya,
Am 25.06.2015 um 14:07 schrieb Ilya Dryomov:
On Wed, Jun 24, 2015 at 10:29 PM, Stefan Priebe <s.priebe@xxxxxxxxxxxx> wrote:
Am 24.06.2015 um 19:53 schrieb Ilya Dryomov:
On Wed, Jun 24, 2015 at 8:38 PM, Stefan Priebe <s.priebe@xxxxxxxxxxxx>
wrote:
Am 24.06.2015 um 16:55 schrieb Nick Fisk:
That kernel probably has the bug where tcp_nodelay is not enabled. That
is fixed in Kernel 4.0+, however also in 4.0 blk-mq was introduced which
brings two other limitations:-
blk-mq is terrible slow. That's correct.
Is that a general sentiment or your experience with rbd? If the
latter, can you describe your workload and provide some before and
after blk-mq numbers? We'd be very interested in identifying and
fixing any performance regressions you might have on blk-mq rbd.
oh i'm sorry. I accidently compiled blk-mq into the kernel when 3.18.1 came
out and i was wondering why my I/O waits on my ceph osds where doubled or
even tripled. After reverting back to cfq everything was fine again. I
didn't digged deeper into it as i thought blk-mq is experimental in 3.18.
That doesn't make sense - rbd was switched to blk-mq in 4.0. Or did
you try to apply the patch from the mailing list to 3.18?
I'm talking about the ceph-osd process / side not about rbd client side.
If you're willing to assist i can give it a try - but need the patches you
mention first (git commit ids?).
No commit ids as the patches are not upstream yet. I have everything
gathered in testing+blk-mq-plug branch of ceph-client.git:
https://github.com/ceph/ceph-client/tree/testing%2Bblk-mq-plug
A deb (ubuntu, debian, etc):
http://gitbuilder.ceph.com/kernel-deb-precise-x86_64-basic/ref/testing_blk-mq-plug/linux-image.deb
An rpm (fedora, centos, rhel):
http://gitbuilder.ceph.com/kernel-rpm-centos7-x86_64-basic/ref/testing_blk-mq-plug/kernel.x86_64.rpm
These are built with slightly stripped down distro configs so it should
boot most boxes.
Thanks,
Ilya
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