Re: [linux-next:master] [mm] 8f33a2ff30: stress-ng.resched.ops_per_sec -10.3% regression

[Uladzislau Rezki <urezki@gmail.com>]

Hello.

> 
> 
> Hello,
> 
> kernel test robot noticed a -10.3% regression of stress-ng.resched.ops_per_sec on:
> 
> 
> commit: 8f33a2ff307248c3e55a7696f60b3658b28edb57 ("mm: vmalloc: set nr_nodes based on CPUs in a system")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> 
> testcase: stress-ng
> test machine: 64 threads 2 sockets Intel(R) Xeon(R) Gold 6346 CPU @ 3.10GHz (Ice Lake) with 256G memory
> parameters:
> 
> 	nr_threads: 100%
> 	testtime: 60s
> 	test: resched
> 	cpufreq_governor: performance
> 
> 
> In addition to that, the commit also has significant impact on the following tests:
> 
> +------------------+-------------------------------------------------------------------------------------------+
> | testcase: change | stress-ng: stress-ng.pthread.ops_per_sec 23.0% improvement                                |
> | test machine     | 64 threads 2 sockets Intel(R) Xeon(R) Gold 6346 CPU @ 3.10GHz (Ice Lake) with 256G memory |
> | test parameters  | cpufreq_governor=performance                                                              |
> |                  | nr_threads=100%                                                                           |
> |                  | test=pthread                                                                              |
> |                  | testtime=60s                                                                              |
> +------------------+-------------------------------------------------------------------------------------------+
> | testcase: change | stress-ng: stress-ng.fstat.ops_per_sec 14.2% improvement                                  |
> | test machine     | 64 threads 2 sockets Intel(R) Xeon(R) Gold 6346 CPU @ 3.10GHz (Ice Lake) with 256G memory |
> | test parameters  | cpufreq_governor=performance                                                              |
> |                  | disk=1HDD                                                                                 |
> |                  | fs=xfs                                                                                    |
> |                  | nr_threads=100%                                                                           |
> |                  | test=fstat                                                                                |
> |                  | testtime=60s                                                                              |
> +------------------+-------------------------------------------------------------------------------------------+
> 
This is good if i understand this correctly.

> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@intel.com>
> | Closes: https://lore.kernel.org/oe-lkp/202402292306.8520763a-oliver.sang@intel.com
> 
> 
> Details are as below:
> -------------------------------------------------------------------------------------------------->
> 
> 
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20240229/202402292306.8520763a-oliver.sang@intel.com
> 
> =========================================================================================
> compiler/cpufreq_governor/kconfig/nr_threads/rootfs/tbox_group/test/testcase/testtime:
>   gcc-12/performance/x86_64-rhel-8.3/100%/debian-12-x86_64-20240206.cgz/lkp-icl-2sp7/resched/stress-ng/60s
> 
> commit: 
>   8e1d743f2c ("mm: vmalloc: support multiple nodes in vmallocinfo")
>   8f33a2ff30 ("mm: vmalloc: set nr_nodes based on CPUs in a system")
> 
> 8e1d743f2c2671aa 8f33a2ff307248c3e55a7696f60 
> ---------------- --------------------------- 
>          %stddev     %change         %stddev
>              \          |                \  
>       7.48            -0.8        6.73        mpstat.cpu.all.nice%
>   10439977           -10.4%    9351864        vmstat.system.cs
>   14670714 ±  3%     +18.1%   17330709 ±  5%  numa-numastat.node0.local_node
>   14688319 ±  3%     +18.1%   17348214 ±  5%  numa-numastat.node0.numa_hit
>   14538034 ±  3%     +15.7%   16824234 ±  4%  numa-numastat.node1.local_node
>   14556613 ±  3%     +15.6%   16834659 ±  4%  numa-numastat.node1.numa_hit
>   14685240 ±  3%     +18.0%   17334251 ±  5%  numa-vmstat.node0.numa_hit
>   14667635 ±  3%     +18.1%   17316745 ±  5%  numa-vmstat.node0.numa_local
>   14551744 ±  3%     +15.6%   16815047 ±  4%  numa-vmstat.node1.numa_hit
>   14533165 ±  3%     +15.6%   16804623 ±  4%  numa-vmstat.node1.numa_local
>  9.153e+08           -10.3%  8.208e+08        stress-ng.resched.ops
>   15220752           -10.3%   13651349        stress-ng.resched.ops_per_sec
>  6.584e+08           -10.8%  5.871e+08        stress-ng.time.involuntary_context_switches
>
This is not. I am working on it to figure out what happens.

--
Uladzislau Rezki