Andrei,
Yes, I see it has lot of potential and I believe fixing the performance bottlenecks inside XIO messenger it should go further.
We are working on it and will keep community posted..
Thanks & Regards
Somnath
From: Andrei Mikhailovsky [mailto:andrei@xxxxxxxxxx]
Sent: Wednesday, April 08, 2015 2:22 AM
To: Andrey Korolyov
Cc: ceph-users@xxxxxxxxxxxxxx; ceph-devel; Somnath Roy
Subject: Re: [ceph-users] Preliminary RDMA vs TCP numbers
Hi,
Am I the only person noticing disappointing results from the preliminary RDMA testing, or am I reading the numbers wrong?
Yes, it's true that on a very small cluster you do see a great improvement in rdma, but in real life rdma is used in large infrastructure projects, not on a few servers with a handful of osds. In fact, from what i've seen from the slides, the rdma implementation
scales horribly to the point that it becomes slower the more osds you through at it.
From my limited knowledge, i have expected a much higher performance gains with rdma, taking into account that you should have much lower latency and overhead and lower cpu utilisation when using this transport in comparison with tcp.
Are we likely to see a great deal of improvement with ceph and rdma in a near future? Is there a roadmap for having a stable and reliable rdma protocol support?
Thanks
Andrei
From:
"Andrey Korolyov" <andrey@xxxxxxx>
To: "Somnath Roy" <Somnath.Roy@xxxxxxxxxxx>
Cc: ceph-users@xxxxxxxxxxxxxx, "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx>
Sent: Wednesday, 8 April, 2015 9:28:12 AM
Subject: Re: [ceph-users] Preliminary RDMA vs TCP numbers
On Wed, Apr 8, 2015 at 11:17 AM, Somnath Roy <Somnath.Roy@xxxxxxxxxxx> wrote:
>
> Hi,
> Please find the preliminary performance numbers of TCP Vs RDMA (XIO) implementation (on top of SSDs) in the following link.
>
> http://www.slideshare.net/somnathroy7568/ceph-on-rdma
>
> The attachment didn't go through it seems, so, I had to use slideshare.
>
> Mark,
> If we have time, I can present it in tomorrow's performance meeting.
>
> Thanks & Regards
> Somnath
>
Those numbers are really impressive (for small numbers at least)! What
are TCP settings you using?For example, difference can be lowered on
scale due to less intensive per-connection acceleration on CUBIC on a
larger number of nodes, though I do not believe that it was a main
reason for an observed TCP catchup on a relatively flat workload such
as fio generates.
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