Re: RDMA/RoCE enablement failed with (113) No route to host

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Thanks for posting this Roman.




-----Original Message-----
From: Roman Penyaev [mailto:rpenyaev@xxxxxxx] 
Sent: 20 December 2018 14:21
To: Marc Roos
Cc: green; mgebai; ceph-users
Subject: Re:  RDMA/RoCE enablement failed with (113) No 
route to host

On 2018-12-19 22:01, Marc Roos wrote:
> I would be interested learning about the performance increase it has 
> compared to 10Gbit. I got the ConnectX-3 Pro but I am not using the 
> rdma because support is not default available.

Not too much, the following is the comparison on latest master using fio 
engine, which measures bare ceph messenger performance (no disk IO):
https://github.com/ceph/ceph/pull/24678


Mellanox MT27710 Family [ConnectX-4 Lx] 25gb/s:


   bs        iodepth=8,  async+posix               iodepth=8,  
async+rdma
----    ---------------------------------     
----------------------------------
   4k    IOPS=30.0k  BW=121MiB/s   0.257ms     IOPS=47.9k  BW=187MiB/s  
0.166ms
   8k    IOPS=30.8k  BW=240MiB/s   0.259ms     IOPS=46.3k  BW=362MiB/s  
0.172ms
  16k    IOPS=25.1k  BW=392MiB/s   0.318ms     IOPS=45.2k  BW=706MiB/s  
0.176ms
  32k    IOPS=23.1k  BW=722MiB/s   0.345ms     IOPS=37.5k  BW=1173MiB/s 
0.212ms
  64k    IOPS=18.0k  BW=1187MiB/s  0.420ms     IOPS=41.0k  BW=2624MiB/s 
0.189ms
128k    IOPS=12.1k  BW=1518MiB/s  0.657ms     IOPS=20.9k  BW=2613MiB/s 
0.381ms
256k    IOPS=3530   BW=883MiB/s   2.265ms     IOPS=4624   BW=1156MiB/s 
1.729ms
512k    IOPS=2084   BW=1042MiB/s  3.387ms     IOPS=2406   BW=1203MiB/s  
3.32ms
   1m    IOPS=1119   BW=1119MiB/s  7.145ms     IOPS=1277   BW=1277MiB/s  

6.26ms
   2m    IOPS=551    BW=1101MiB/s  14.51ms     IOPS=631    BW=1263MiB/s 
12.66ms
   4m    IOPS=272    BW=1085MiB/s  29.45ms     IOPS=318    BW=1268MiB/s 
25.17ms



   bs        iodepth=128,  async+posix               iodepth=128,  
async+rdma
----    ---------------------------------     
----------------------------------
   4k    IOPS=75.9k  BW=297MiB/s  1.683ms      IOPS=83.4k  BW=326MiB/s   

1.535ms
   8k    IOPS=64.3k  BW=502MiB/s  1.989ms      IOPS=70.3k  BW=549MiB/s   

1.819ms
  16k    IOPS=53.9k  BW=841MiB/s  2.376ms      IOPS=57.8k  BW=903MiB/s   

2.214ms
  32k    IOPS=42.2k  BW=1318MiB/s 3.034ms      IOPS=59.4k  BW=1855MiB/s  

2.154ms
  64k    IOPS=30.0k  BW=1934MiB/s 4.135ms      IOPS=42.3k  BW=2645MiB/s  

3.023ms
128k    IOPS=18.1k  BW=2268MiB/s 7.052ms      IOPS=21.2k  BW=2651MiB/s  
6.031ms
256k    IOPS=5186   BW=1294MiB/s 24.71ms      IOPS=5253   BW=1312MiB/s  
24.39ms
512k    IOPS=2897   BW=1444MiB/s 44.19ms      IOPS=2944   BW=1469MiB/s  
43.48ms
   1m    IOPS=1306   BW=1297MiB/s 97.98ms      IOPS=1421   BW=1415MiB/s  

90.27ms
   2m    IOPS=612    BW=1199MiB/s 208.6ms      IOPS=862    BW=1705MiB/s  

148.9ms
   4m    IOPS=316    BW=1235MiB/s 409.1ms      IOPS=416    BW=1664MiB/s  

307.4ms


1. As you can see there is no big difference between posix and rdma.

2. Even 25gb/s card is used we barely reach 20gb/s.  I have also results
    on 100gb/s qlogic cards, no difference, because the bottleneck is 
not
    a network.  This is especially visible on loads with bigger number 
of
    iopdeth: bandwidth is not significantly changed. So even you 
increase
    number of requests in-flight you reach the limit how fast those
    requests are processed.

3. Keep in mind this is only messenger performance, so on real ceph 
loads you
    will get less, because of the whole IO stack involved.


--
Roman


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