Re: [LKP] [fs/locks] 83b381078b: will-it-scale.per_thread_ops -62.5% regression

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Thanks for the report!

On Tue, Nov 27, 2018 at 02:01:02PM +0800, kernel test robot wrote:
> FYI, we noticed a -62.5% regression of will-it-scale.per_thread_ops due to commit:
> 
> 
> commit: 83b381078b5ecab098ebf6bc9548bb32af1dbf31 ("fs/locks: always delete_block after waiting.")
> https://git.kernel.org/cgit/linux/kernel/git/jlayton/linux.git locks-next
> 
> in testcase: will-it-scale
> on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 64G memory
> with following parameters:
> 
> 	nr_task: 16
> 	mode: thread
> 	test: lock1

So I guess it's doing this, uncontended file lock/unlock?:

	https://github.com/antonblanchard/will-it-scale/blob/master/tests/lock1.c

Each thread is repeatedly locking and unlocking a file that is only used
by that thread.

By the way, what's the X-axis on these graphs?  (Or the y-axis, for that
matter?)

--b.

>                             will-it-scale.per_thread_ops                        
>                                                                                 
>   450000 +-+----------------------------------------------------------------+   
>          |                                                                  |   
>   400000 +-+   +..+..  .+..+..  .+..+..+...+..+..+..   +..        .+..    ..|   
>   350000 +-+ ..      +.       +.                     ..         +.    +..+  |   
>          |  +                                       +     +     :           |   
>   300000 +-+                                              :    :            |   
>   250000 +-+                                               :   :            |   
>          |                                                 :   :            |   
>   200000 +-+                                               :   :            |   
>   150000 +-+                                                : :             |   
>          O  O  O  O  O  O  O  O  O  O  O   O  O  O  O  O  O :O: O  O  O  O  O   
>   100000 +-+                                                : :             |   
>    50000 +-+                                                : :             |   
>          |                                                   :              |   
>        0 +-+----------------------------------------------------------------+   
>                                                                                 
>                                                                                                                                                                 
>                                will-it-scale.workload                           
>                                                                                 
>   7e+06 +-+-----------------------------------------------------------------+   
>         |              +...+..           .+..+..+     +            +..      |   
>   6e+06 +-+   +..+.. ..         .+..+..+.        +   + +         ..       ..|   
>         |   ..      +         +.                  + +   +       +     +..+  |   
>   5e+06 +-++                                       +     +      :           |   
>         |                                                :     :            |   
>   4e+06 +-+                                               :    :            |   
>         |                                                 :    :            |   
>   3e+06 +-+                                                :   :            |   
>         |                                       O     O    :  : O  O        |   
>   2e+06 O-+O  O  O  O  O   O  O  O  O  O  O  O     O     O : O:       O  O  O   
>         |                                                   : :             |   
>   1e+06 +-+                                                 : :             |   
>         |                                                    :              |   
>       0 +-+-----------------------------------------------------------------+   
>                                                                                 
>                                                                                                                                                                 
>                            will-it-scale.time.user_time                         
>                                                                                 
>   250 +-+-------------------------------------------------------------------+   
>       |                 .+..               .+..                   +..       |   
>       |..   +...+..  .+.      .+...+..+..+.    +..    +..       ..   .    ..|   
>   200 +-+ ..       +.       +.                    . ..         +      +..+  |   
>       |  +                                         +     +     :            |   
>       |                                                  :    :             |   
>   150 +-+                                                 :   :             |   
>       |                                                   :   :             |   
>   100 +-+                                                 :   :             |   
>       |  O      O                                          : :              |   
>       O     O      O  O  O  O  O   O  O  O  O  O   O  O  O :O: O  O   O  O  O   
>    50 +-+                                                  : :              |   
>       |                                                    : :              |   
>       |                                                     :               |   
>     0 +-+-------------------------------------------------------------------+   
>                                                                                 
>                                                                                                                                                                 
>                           will-it-scale.time.system_time                        
>                                                                                 
>   5000 +-+------------------------------------------------------------------+   
>   4500 O-+O..O..O...O..O..O..O..O..O..O...O..O..O..O..O..O  O  O...O..O..O..O   
>        |                                                 :     :            |   
>   4000 +-+                                               :     :            |   
>   3500 +-+                                                :   :             |   
>        |                                                  :   :             |   
>   3000 +-+                                                :   :             |   
>   2500 +-+                                                :   :             |   
>   2000 +-+                                                 : :              |   
>        |                                                   : :              |   
>   1500 +-+                                                 : :              |   
>   1000 +-+                                                 : :              |   
>        |                                                    :               |   
>    500 +-+                                                  :               |   
>      0 +-+------------------------------------------------------------------+   
>                                                                                 
>                                                                                 
> [*] bisect-good sample
> [O] bisect-bad  sample



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