Collectl seems to disagree with itself when reporting infiniband bandwidth
usage.
I'm running a bandwidth benchmark that reports appr. 7 GB/s bidirectional
bandwidth on our QDR infiniband network:
Benchmark exchange(MPI_Sendrecv)
================================
lenght iterations elapsed time transfer rate latency
(bytes) (count) (seconds) (Mbytes/s) (usec)
--------------------------------------------------------------------------
12582912 8578 30.626 7048.6 1785.2
Running collectl interactively shows approximately the same
[root@c10-13 etc]# collectl -s x
Couldn't find 'ofed_info'. Won't be able to determine OFED version
waiting for 1 second sample...
#<-----------InfiniBand----------->
# KBIn PktIn KBOut PktOut Errs
3472553 1717K 3472483 1717K 0
3472962 1717K 3472977 1717K 0
3472570 1717K 3472629 1717K 0
3470588 1716K 3470598 1716K 0
3472094 1717K 3472105 1717K 0
3471221 1716K 3471156 1716K 0
3472378 1717K 3472409 1717K 0
But if I run it as a daemon, with this addition to DaemonCommands in
collectl.conf, -P --export lexpr,f=/tmp/L, (*) it only reports half the
bandwidth usage
[root@c10-13 etc]# grep iconnect /tmp/L
iconnect.kbin 1677721
iconnect.pktin 1722455
iconnect.kbout 1677721
iconnect.pktout 1722455
Is this a bug? Any workarounds?
The test was done with collectl 3.6.9.
* I use this to report infiniband traffic in ganglia,
https://wiki.rocksclusters.org/wiki/index.php/Roy_Dragseth#Integrating_collectl_and_ganglia
--
The Computer Center, University of Tromsø, N-9037 TROMSØ Norway.
phone:+47 77 64 41 07, fax:+47 77 64 41 00
Roy Dragseth, Team Leader, High Performance Computing
Direct call: +47 77 64 62 56. email: [email protected]
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