Re: [LKP] [fs/locks] fd7732e033: stress-ng.eventfd.ops 21.9% improvement

[J. Bruce Fields]

On Tue, Dec 11, 2018 at 05:14:29PM +0800, kernel test robot wrote:
> FYI, we noticed a 21.9% improvement of stress-ng.eventfd.ops due to commit:

So, doesn't sound like a problem, but just looking into it out of
curiosity.....

I love that you do this, but these reports can be hard to figure out
sometimes.  The graphs especially could use better labeling.

> commit: fd7732e033e30b3a586923b57e338c859e17858a ("fs/locks: create a tree of dependent requests.")
> https://git.kernel.org/cgit/linux/kernel/git/jlayton/linux.git locks-next
> 
> in testcase: stress-ng
> on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 64G memory
> with following parameters:
> 
> 	nr_threads: 100%
> 	disk: 1HDD
> 	testtime: 1s
> 	class: filesystem
> 	ucode: 0xb00002e
> 	cpufreq_governor: performance

Looking at the man page for stress-ng, it doesn't say much about what it
actually does.  It does say not to use stress-ng as a benchmark.  I
can't tell if it does file locking--the man pages does document some
options which ask for locking (--flock, --locka, --lockf) but I don't
see any evidence in the yaml file or elsewhere that those options are in
use?

These graphs could really use units on the axes.  Also:

>                                  stress-ng.fcntl.ops                            
>                                                                                 
>   120000 +-+----------------------------------------------------------------+   
>          O     O    O O O      O   O O O O  O O O O O O  O   O              |   
>   110000 +-O O    O       O O    O                         O                |   
>   100000 +-+                                                                |   
>          |                                                                  |   
>    90000 +-+                                                                |   
>    80000 +-+                                                                |   
>          |                                                                  |   
>    70000 +-+                                                                |   
>    60000 +-+                                                                |   
>          |                                                                  |   
>    50000 +-+                                                                |   
>    40000 +-+                                                                |   
>          |. .+.+..+.+.   .+.+..+.+. .+.+.+..+. .+.   .+.. .+.   .+.      .+.|   
>    30000 +-+----------------------------------------------------------------+   
>                                                                                 
>                                                                                                                                                                 
>                              stress-ng.fcntl.ops_per_sec                        
>                                                                                 
>   120000 +-+----------------------------------------------------------------+   
>          O     O    O O O      O   O O O O  O O O O O O  O   O              |   
>   110000 +-O O    O       O O    O                         O                |   
>   100000 +-+                                                                |   
>          |                                                                  |   
>    90000 +-+                                                                |   
>    80000 +-+                                                                |   
>          |                                                                  |   
>    70000 +-+                                                                |   
>    60000 +-+                                                                |   
>          |                                                                  |   
>    50000 +-+                                                                |   
>    40000 +-+                                                                |   
>          |. .+.+..+.+.   .+.+..+.+. .+.+.+..+. .+.   .+.. .+.   .+.      .+.|   
>    30000 +-+----------------------------------------------------------------+   
>                                                                                 
>                                                                                 
> [*] bisect-good sample
> [O] bisect-bad  sample

I see O's, not but any *'s.  And what are the +'s?

--b.