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SubjectRe: [LKP] Re: 2463a604a8: netperf.Throughput_tps 12.8% improvement
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On 5/26/2021 12:44 AM, Bart Van Assche wrote:
> On 5/24/21 11:44 PM, kernel test robot wrote:
>> FYI, we noticed a 12.8% improvement of netperf.Throughput_tps due to commit:
>>
>> commit: 2463a604a86728777ce4284214a52de46a808c9e ("[PATCH v3 2/3] Introduce enums for the SAM, message, host and driver status codes")
>> url: https://github.com/0day-ci/linux/commits/Bart-Van-Assche/Introduce-enums-for-SCSI-status-codes/20210524-105751
>> base: https://git.kernel.org/cgit/linux/kernel/git/mkp/scsi.git for-next
>>
>> in testcase: netperf
>> on test machine: 192 threads 4 sockets Intel(R) Xeon(R) Platinum 9242 CPU @ 2.30GHz with 192G memory
>> with following parameters:
>>
>> ip: ipv4
>> runtime: 300s
>> nr_threads: 16
>> cluster: cs-localhost
>> test: TCP_CRR
>> cpufreq_governor: performance
>> ucode: 0x5003006
>>
>> test-description: Netperf is a benchmark that can be use to measure various aspect of networking performance.
>> test-url: http://www.netperf.org/netperf/
> The above email reports a performance improvement for the networking
> subsystem while my patch only affects the SCSI subsystem and should not
> have any performance impact. I'm confused by the above feedback ...

I suspect it related with cache alignment, 2463a604a8 changes "u8"
(size:1) to "enum xxx_status" (size: 4),  the cache alignment is better
than before , so cause the improvement.
>
> Bart.
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--
Zhengjun Xing

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