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

On 08/23/2016 05:44 AM, Marcelo Ricardo Leitner wrote: > Em 19-08-2016 04:24, Aaron Lu escreveu: >> On Fri, Aug 19, 2016 at 04:19:39AM -0300, Marcelo Ricardo Leitner wrote: >>> Hi, >>> >>> Em 19-08-2016 02:29, Aaron Lu escreveu: >>> ... >>>> It doesn't look insane and sctp_wait_for_sndbuf may actually have >>>> something to do with a larger sctp_chunk I suppose? >>>> >>>> The same perf record doesn't capture any sample for the good commit, >>>> which suggests the nerperf process doesn't sleep in sctp_wait_for_sndbuf. >>> >>> Ahhh yes! It does, and then it would mean your txbuf is too small for the >>> chunk sizes you're using (sctp tests option -m). >>> >>> What's your netperf cmdline again please? >> >> netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 >> >> Is the 10K used here a problem? If so, can you suggest a proper value >> for our netperf performance test? Thanks. > > We're still working on this. Xin could reproduce it on an i3 too, but > I'm afraid this commit just unmasked an issue in there. You're > overloading the CPU by too much when spawning 8 parallel netperf's on a > 4-core system, seems that commit a6c2f79287 was that last rock that made > it slip into a precipice. sctp's cwnd and rwnd management are not as > good as tcp's and now it seems you're triggering a corner case. > > I hope to have more soon. I wonder if there is any update on this issue?