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Message-ID: <20160817061405.GA5401@aaronlu.sh.intel.com>
Date: Wed, 17 Aug 2016 14:14:05 +0800
From: Aaron Lu <aaron.lu@...el.com>
To: Xin Long <lucien.xin@...il.com>
Cc: kernel test robot <xiaolong.ye@...el.com>,
Stephen Rothwell <sfr@...b.auug.org.au>, lkp@...org,
"David S. Miller" <davem@...emloft.net>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [LKP] [lkp] [sctp] a6c2f79287: netperf.Throughput_Mbps -37.2%
regression
On Wed, Aug 17, 2016 at 01:41:04PM +0800, Xin Long wrote:
> > The perf-profile data for the two commits are attached(for the case of
> > prsctp_enable=1, the perf-profile data doesn't get collected for the 0
> > case for some reason, I'm checking the problem now).
> >
> > The CPU gets much more idle time in the bisected commit a6c2f79287:
> >
> > 68.89% 0.70% [kernel.kallsyms] [k] entry_SYSCALL_64_fastpath
> > 49.32% 0.12% [kernel.kallsyms] [k] sys_sendmsg
> > 49.17% 0.12% [kernel.kallsyms] [k] __sys_sendmsg
> > 48.58% 0.22% [kernel.kallsyms] [k] ___sys_sendmsg
> > 46.69% 0.06% [kernel.kallsyms] [k] sock_sendmsg
> > 46.31% 0.16% [kernel.kallsyms] [k] inet_sendmsg
> > 45.90% 0.98% [kernel.kallsyms] [k] sctp_sendmsg
> > 29.66% 0.45% [kernel.kallsyms] [k] sctp_do_sm
> > 29.54% 0.23% [kernel.kallsyms] [k] cpu_startup_entry
> > 28.81% 0.68% [kernel.kallsyms] [k] sctp_cmd_interpreter.isra.24
> > 26.20% 0.00% [kernel.kallsyms] [k] start_secondary
> > 23.04% 0.09% [kernel.kallsyms] [k] sctp_inq_push
> > 23.03% 0.08% [kernel.kallsyms] [k] call_cpuidle
> > 22.94% 0.00% [kernel.kallsyms] [k] cpuidle_enter
> > 22.60% 0.18% [kernel.kallsyms] [k] cpuidle_enter_state
> > 21.99% 21.99% [kernel.kallsyms] [k] intel_idle
> > ... ...
> >
> > While its immediate parent commit 826d253d57 is mostly busy working:
> >
> > 98.53% 0.83% [kernel.kallsyms] [k] entry_SYSCALL_64_fastpath
> > 78.13% 0.12% [kernel.kallsyms] [k] sys_sendmsg
> > 78.03% 0.16% [kernel.kallsyms] [k] __sys_sendmsg
> > 77.08% 0.28% [kernel.kallsyms] [k] ___sys_sendmsg
> > 74.44% 0.08% [kernel.kallsyms] [k] sock_sendmsg
> > 73.82% 0.13% [kernel.kallsyms] [k] inet_sendmsg
> > 73.34% 1.44% [kernel.kallsyms] [k] sctp_sendmsg
> > 47.52% 0.75% [kernel.kallsyms] [k] sctp_do_sm
> > 46.19% 0.90% [kernel.kallsyms] [k] sctp_cmd_interpreter.isra.24
> > 37.17% 1.43% [kernel.kallsyms] [k] sctp_outq_flush
> > 36.93% 0.08% [kernel.kallsyms] [k] sctp_outq_uncork
> > 34.24% 0.15% [kernel.kallsyms] [k] sctp_inq_push
> > ... ...
> > No idle related function above 1%.
> >
> > Will the bisected commit make the idle possible?
> No, not at all. :)
>
> pls help to debug as I said in the last reply.
OK, will see how to do that.
In the meantime, I just tried to reproduce on my own desktop:
Sandybridge i7-2600 CPU @ 3.40GHz and it reproduced:
$ cat 4.7.0-rc6-01198-ga6c2f792873a/0/netperf.json
{
"netperf.Throughput_Mbps": [
752.9450000000002
]
}
$ cat 4.7.0-rc6-01197-g826d253d57b1/0/netperf.json
{
"netperf.Throughput_Mbps": [
1068.5556249999997
]
}
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