Re: [mm/page_alloc] 7fef431be9: vm-scalability.throughput 87.8% improvement

[David Rientjes]

On Wed, 21 Oct 2020, kernel test robot wrote:

> Greeting,
> 
> FYI, we noticed a 87.8% improvement of vm-scalability.throughput due to commit:
> 
> 
> commit: 7fef431be9c9ac255838a9578331567b9dba4477 ("mm/page_alloc: place pages to tail in __free_pages_core()")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> 
> 
> in testcase: vm-scalability
> on test machine: 192 threads Intel(R) Xeon(R) Platinum 9242 CPU @ 2.30GHz with 192G memory
> with following parameters:
> 
> 	runtime: 300s
> 	size: 512G
> 	test: anon-wx-rand-mt
> 	cpufreq_governor: performance
> 	ucode: 0x5002f01
> 
> test-description: The motivation behind this suite is to exercise functions and regions of the mm/ of the Linux kernel which are of interest to us.
> test-url: https://git.kernel.org/cgit/linux/kernel/git/wfg/vm-scalability.git/
> 

I'm curious why we are not able to reproduce this improvement on Skylake 
and actually see a slight performance degradation, at least for 
300s_128G_truncate_throughput.

Axel Rasmussen <axelrasmussen@xxxxxxxxxx> can provide more details on our 
results.