linux-kernel - Re: [PATCH] fs: remove fget_many and fput

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Date:   Mon, 1 Nov 2021 12:25:52 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Gou Hao <gouhao@...ontech.com>
Cc:     viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, jiaofenfang@...ontech.com
Subject: Re: [PATCH] fs: remove fget_many and fput_many interface

On Mon, Nov 01, 2021 at 01:19:31PM +0800, Gou Hao wrote:
> From: gouhao <gouhao@...ontech.com>
> 
> These two interface were added in 091141a42 commit,
> but now there is no place to call them.

For completeness, the only user of these APIs was removed in commit
62906e89e63b ("io_uring: remove file batch-get optimisation").
A user of get_file_rcu_many() (which you didn't mention) were also
removed in f073531070d2 ("init: add an init_dup helper").

> And replace atomic_long_sub/add to atomic_long_dec/inc
> can improve performance.
> 
> Here are the test results of unixbench:
> 
> Cmd: ./Run -c 64 context1
> 
> Without patch:
> System Benchmarks Partial Index              BASELINE       RESULT    INDEX
> Pipe-based Context Switching                   4000.0    2798407.0   6996.0
>                                                                    ========
> System Benchmarks Index Score (Partial Only)                         6996.0
> 
> With patch:
> System Benchmarks Partial Index              BASELINE       RESULT    INDEX
> Pipe-based Context Switching                   4000.0    3486268.8   8715.7
>                                                                    ========
> System Benchmarks Index Score (Partial Only)                         8715.7

This seems impressive.  What's the stddev of this benchmark?