Re: [LKP] [rcu] c0f489d2c6f: -1.5% netperf.Throughput_tps

From: Aaron Lu
Date: Fri Jul 25 2014 - 10:31:59 EST

On 07/25/2014 05:44 PM, Mike Galbraith wrote:
> On Fri, 2014-07-25 at 16:05 +0800, Aaron Lu wrote:
>> On 07/25/2014 03:35 PM, Mike Galbraith wrote:
>>> On Fri, 2014-07-25 at 14:45 +0800, Aaron Lu wrote:
>>>> FYI, we noticed the below changes on
>>>> git:// master
>>>> commit c0f489d2c6fec8994c642c2ec925eb858727dc7b ("rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs")
>>>> abaa93d9e1de2c2 c0f489d2c6fec8994c642c2ec
>>>> --------------- -------------------------
>>>> 12654 ~ 0% -1.5% 12470 ~ 0% ivb43/netperf/300s-25%-TCP_CRR
>>>> 12654 ~ 0% -1.5% 12470 ~ 0% TOTAL netperf.Throughput_tps
>>> Out of curiosity, what parameters do you use for this test? In my
>> The cmdline for this test is:
>> netperf -t TCP_CRR -c -C -l 300
> Thanks. That doesn't switch as heftily as plain TCP_RR, but I'd still
> expect memory layout etc to make bisection frustrating as heck. But no
> matter, I was just curious.

The bisect is done by the LKP test system(developed by Fengguang)
automatically so it's not that painful for me :-) But as you have said,
the 1.5% change is too small and probably doesn't worth a report, I'll
be more careful next time when examining the report.

> Aside: running unbound, the load may get beaten up pretty bad by nohz if
> it's enabled. Maybe for testing the network stack it'd be better to
> remove that variable? Dunno, just a thought. I only mention it because

The CONFIG_NO_HZ_FULL is set to y, I'll disable it to see if the number
changes, thanks for the tips.


> your numbers look very low unless the box is ancient or CPU is dinky.
> -Mike

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