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Date:   Wed, 19 May 2021 20:38:39 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Nadav Amit <namit@vmware.com>
Cc:     kernel test robot <oliver.sang@intel.com>,
        Ingo Molnar <mingo@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "lkp@lists.01.org" <lkp@lists.01.org>,
        kernel test robot <lkp@intel.com>,
        "Huang, Ying" <ying.huang@intel.com>,
        "feng.tang@intel.com" <feng.tang@intel.com>,
        "zhengjun.xing@intel.com" <zhengjun.xing@intel.com>
Subject: Re: [smp]  a32a4d8a81:  netperf.Throughput_tps -2.1% regression
Message-ID: <20210519183839.GH21560@worktop.programming.kicks-ass.net>
References: <20210519142742.GA5275@xsang-OptiPlex-9020>
 <16A4D949-D82D-4034-B5A4-DE4DADE15884@vmware.com>
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On Wed, May 19, 2021 at 06:17:35PM +0000, Nadav Amit wrote:
> >      1287 =B1 42%     +75.3%       2256 =B1 14%  interrupts.CPU111.CAL:=
Function_call_interrupts
> >      1326 =B1 43%     +71.0%       2267 =B1 13%  interrupts.CPU119.CAL:=
Function_call_interrupts
> >      1300 =B1 45%     +75.9%       2287 =B1 37%  interrupts.CPU120.CAL:=
Function_call_interrupts
> >      1299 =B1 45%     +60.1%       2081 =B1 28%  interrupts.CPU128.CAL:=
Function_call_interrupts
> >      1305 =B1 45%     +61.7%       2110 =B1 29%  interrupts.CPU131.CAL:=
Function_call_interrupts
> >      1299 =B1 45%     +61.8%       2102 =B1 28%  interrupts.CPU139.CAL:=
Function_call_interrupts
> >     66.67 =B1133%     -97.2%       1.83 =B1155%  interrupts.CPU14.TLB:T=
LB_shootdowns
> >      1299 =B1 45%    +107.8%       2700 =B1 33%  interrupts.CPU142.CAL:=
Function_call_interrupts
> >    301.83 =B1128%     -95.6%      13.17 =B1140%  interrupts.CPU149.RES:=
Rescheduling_interrupts
> >    389.17 =B1 89%     -73.5%     103.17 =B1 35%  interrupts.CPU164.NMI:=
Non-maskable_interrupts
> >    389.17 =B1 89%     -73.5%     103.17 =B1 35%  interrupts.CPU164.PMI:=
Performance_monitoring_interrupts
> >      1299 =B1 45%     +60.2%       2081 =B1 28%  interrupts.CPU35.CAL:F=
unction_call_interrupts
> >      1244 =B1 50%     +66.8%       2076 =B1 27%  interrupts.CPU45.CAL:F=
unction_call_interrupts
> >      1300 =B1 44%     +59.5%       2075 =B1 28%  interrupts.CPU46.CAL:F=
unction_call_interrupts
> >      1.50 =B1 63%   +1422.2%      22.83 =B1167%  interrupts.CPU47.RES:R=
escheduling_interrupts
> >    467.33 =B1 85%     -64.6%     165.67 =B1 74%  interrupts.CPU58.NMI:N=
on-maskable_interrupts
> >    467.33 =B1 85%     -64.6%     165.67 =B1 74%  interrupts.CPU58.PMI:P=
erformance_monitoring_interrupts
> >    306.67 =B1 75%     -59.9%     122.83 =B1 16%  interrupts.CPU68.NMI:N=
on-maskable_interrupts
> >    306.67 =B1 75%     -59.9%     122.83 =B1 16%  interrupts.CPU68.PMI:P=
erformance_monitoring_interrupts
> >      1131 =B1 27%     +61.2%       1822 =B1 35%  interrupts.CPU85.CAL:F=
unction_call_interrupts
> >      1180 =B1 31%     +79.6%       2119 =B1 24%  interrupts.CPU86.CAL:F=
unction_call_interrupts
> >=20

It looks to be sending *waay* more call IPIs, did we mess up the mask or
loose an optimization somewhere?

I'll go read the commit again...