Re: [LKP] [lkp] [sctp] a6c2f79287: netperf.Throughput_Mbps -37.2% regression

[Aaron Lu]

On Fri, Aug 05, 2016 at 07:53:38PM +0800, Xin Long wrote:
> >> It doesn't make much sense to me. the codes I added cannot be
> >> triggered without enable any pr policies. and I also did the tests in
> >
> > It seems these pr policies has to be turned on by user space, i.e.
> > netperf in this case?
> >
> > I checked netperf's source code, it doesn't seem set any option
> > related to SCTP PR POLICY but I'm new to network code so I could be
> > wrong or missing something.
> >
> >> my local environment,  the result looks normal to me compare to
> >> prior version.
> >
> > Can you share your number?
> > We run netperf like this:
> > netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1
> > The full log of the run is attached for your reference.
> 
> Now I also changed to linux-net.git
> 
> commit 96b585267f552d4b6a28ea8bd75e5ed03deb6e71
> [root@hp-dl388g8-08 ~]# uname -r
> 4.7.0.new
> [root@hp-dl388g8-08 ~]# netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 --
> -m 10K -H 127.0.0.1
> SCTP 1-TO-MANY STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to
> 127.0.0.1 () port 0 AF_INET
> Recv   Send    Send                          Utilization       Service Demand
> Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
> Size   Size    Size     Time     Throughput  local    remote   local   remote
> bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
> 
> 212992 212992  10240    300.00     11814.56   4.65     4.65     0.775   0.774
> 
> 
> commit f959fb442c35f4b61fea341401b8463dd0a1b959 (just before the buggie patch)

I'm testing on Linus' master, can we all use that please?

> [root@localhost ~]# netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m
> 10K -H 127.0.0.1
> SCTP 1-TO-MANY STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to
> 127.0.0.1 () port 0 AF_INET
> Recv   Send    Send                          Utilization       Service Demand
> Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
> Size   Size    Size     Time     Throughput  local    remote   local   remote
> bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB   us/KB
> 
> 212992 212992  10240    300.00     9454.90   5.22     5.22     1.086   1.085
> 
> 
> I did tests on physical machine.
> did you do it on guest ?

The test is done on a ivy-bridge desktop with 8G memory:
# cpudesc : Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz
# total memory : 8058152 kB

> 
> >
> >>
> >> Recently the sctp performance is not stable,  as during these patches,
> >> netperf cannot get the result, but return ENOTCONN. which may
> >> also affect the testing. anyway we've fixed the -ENOTCONN issue
> >> already in the latest version.
> >
> > I tested commit 96b585267f55, which is Linus' git tree HEAD on 08/03, I
> > guess the fix you mentioned should already be in there? But
> > unfortunately, the throughput of netperf is still at low number(we did
> > the test 5 times):
> > $ cat */netperf.json
> > {
> >   "netperf.Throughput_Mbps": [
> >     2470.6974999999998
> >   ]
> > }{
> >   "netperf.Throughput_Mbps": [
> >     2486.7675
> >   ]
> > }{
> >   "netperf.Throughput_Mbps": [
> >     2478.945
> >   ]
> > }{
> >   "netperf.Throughput_Mbps": [
> >     2429.465
> >   ]
> > }{
> >   "netperf.Throughput_Mbps": [
> >     2476.9150000000004
> >   ]
> >
> > Considering what you have said that the patch shouldn't make a
> > difference, the performance drop is really confusing. Any idea what
> > could be the cause? Thanks.
> Now I saw your tests result against the new kernel
> 
> Could you do the same test on the kernel before the problematic commit ?

Yes, the throughput of its parent commit is higer enough to trigger the
automatic bisect and then we send out the report.

Throughput of its parent commit 826d253d57b1("sctp: add SCTP_PR_ASSOC_STATUS
on sctp sockopt"):
Average:
"netperf.Throughput_Mbps": 3923.84375,

$ cat */netperf.json
{
  "netperf.Throughput_Mbps": [
    3869.25375
  ]
}{
  "netperf.Throughput_Mbps": [
    3952.58875
  ]
}{
  "netperf.Throughput_Mbps": [
    3936.89625
  ]
}{
  "netperf.Throughput_Mbps": [
    3936.63625
  ]
}

Feel free to let me know if you need any more information or you want me
to do more tests on other commits/machines, thanks.

Regards,
Aaron