linux-kernel - Re: [PATCH v3] pipe: use __pipe_{lock,unlock} instead of spinlock

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Date:   Fri, 6 Jan 2023 11:13:07 -0800
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Hongchen Zhang <zhanghongchen@...ngson.cn>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
        David Howells <dhowells@...hat.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Randy Dunlap <rdunlap@...radead.org>,
        Eric Dumazet <edumazet@...gle.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] pipe: use __pipe_{lock,unlock} instead of spinlock

On Fri, Jan 06, 2023 at 05:48:44PM +0800, Hongchen Zhang wrote:
> Use spinlock in pipe_read/write cost too much time,IMO
> pipe->{head,tail} can be protected by __pipe_{lock,unlock}.
> On the other hand, we can use __pipe_{lock,unlock} to protect
> the pipe->{head,tail} in pipe_resize_ring and
> post_one_notification.
> 
> I tested this patch using UnixBench's pipe test case on a x86_64
> machine,and get the following data:
> 1) before this patch
> System Benchmarks Partial Index  BASELINE       RESULT    INDEX
> Pipe Throughput                   12440.0     493023.3    396.3
>                                                         ========
> System Benchmarks Index Score (Partial Only)              396.3
> 
> 2) after this patch
> System Benchmarks Partial Index  BASELINE       RESULT    INDEX
> Pipe Throughput                   12440.0     507551.4    408.0
>                                                         ========
> System Benchmarks Index Score (Partial Only)              408.0
> 
> so we get ~3% speedup.
> 
> Signed-off-by: Hongchen Zhang <zhanghongchen@...ngson.cn>
> ---

After the above "---" line you should have the changlog descrption.
For instance:

v3:
  - fixes bleh blah blah
v2:
  - fixes 0-day report by ... etc..
  - fixes spelling or whatever

I cannot decipher what you did here differently, not do I want to go
looking and diff'ing. So you are making the life of reviewer harder.

  Luis