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    SubjectRe: [LKP] [lkp] [sctp] a6c2f79287: netperf.Throughput_Mbps -37.2% regression
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    Date
    On 08/16/2016 05:56 PM, Xin Long wrote:
    >>>>
    >>>> I'm testing on Linus' master, can we all use that please?
    >>>>
    >>>
    >>> [git] git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
    >>>
    >>> [mechine]
    >>> Intel(R) Xeon(R) CPU E5-2690 v2 @ 3.00GHz
    >>> mem 62G (66000220K)
    >>>
    >>> [system]
    >>> # cat /etc/redhat-release
    >>> Red Hat Enterprise Linux Server release 7.3 Beta (Maipo)
    >>>
    >>> [commit 3684b03]
    >>> [root@hp-dl380pg8-11 lxin]# uname -r
    >>> 4.8.0-rc2.3684b03
    >>> [root@hp-dl380pg8-11 lxin]# cat test.sh
    >>> killall -0 netserver || netserver -4 &
    >>> netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1
    >>
    >> I just realized the test we are doing is not exactly the same.
    >> As the original report says:
    >> ip: ipv4
    >> runtime: 300s
    >> nr_threads: 200%
    >> cluster: cs-localhost
    >> send_size: 10K
    >> test: SCTP_STREAM_MANY
    >> cpufreq_governor: performance
    >>
    >> Note the nr_threads: 200%, which means to start 2 times of CPU number
    >> processes of netperf.
    >>
    >> In our IVB i3(2 cores, 2 threads per core) case, 8 netperf processes
    >> are started concurrently:
    > OK, understand.
    >
    >>
    >> 2016-07-27 03:48:09 netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 &
    >> 2016-07-27 03:48:09 netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 &
    >> 2016-07-27 03:48:09 netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 &
    >> 2016-07-27 03:48:09 netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 &
    >> 2016-07-27 03:48:09 netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 &
    >> 2016-07-27 03:48:09 netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 &
    >> 2016-07-27 03:48:09 netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 &
    >> 2016-07-27 03:48:09 netperf -4 -t SCTP_STREAM_MANY -c -C -l 300 -- -m 10K -H 127.0.0.1 &
    >>
    >> The throughput is the average of those runs.
    >>
    >> And I think we should be doing test on:
    >> commit a6c2f79287 ("sctp: implement prsctp TTL policy") (the bisected one)
    >> and
    >> commit 826d253d57 ("sctp: add SCTP_PR_ASSOC_STATUS on sctp sockopt") (its immediate parent)
    >> instead of Linus' master HEAD to avoid other factors.
    >>
    > OK, I will do tests as your suggestion now, but need to rebuild again :D
    >
    > can you disable pr_enable with "sysctl -w net.sctp.prsctp_enable=0",
    > then try again?

    For commit a6c2f79287 ("sctp: implement prsctp TTL policy"), no matter
    the value of net.sctp.prsctp_enable, the throughput is almost the same:

    net.sctp.prsctp_enable = 0
    {
    "netperf.Throughput_Mbps": [
    2353.3112499999997
    ]
    }

    net.sctp.prsctp_enable = 1
    {
    "netperf.Throughput_Mbps": [
    2371.5862500000003
    ]
    }

    For its immediate parent:
    commit 826d253d57 ("sctp: add SCTP_PR_ASSOC_STATUS on sctp sockopt")
    No matter the value of net.sctp.prsctp_enable, the throughput is again
    almost the same:

    net.sctp.prsctp_enable = 0
    {
    "netperf.Throughput_Mbps": [
    3838.8300000000004
    ]
    }

    net.sctp.prsctp_enable = 1
    {
    "netperf.Throughput_Mbps": [
    3751.4600000000005
    ]
    }

    Does this result give any hint?

    Thanks,
    Aaron

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