linux-kernel - Re: [PATCH] driver core: auxiliary bus: Optimize auxiliary_match

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Message-ID: <f01e5ce0-6e23-4d1e-bd3a-b4e18bb3286b@icloud.com>
Date: Tue, 2 Sep 2025 20:42:24 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Dave Ertman <david.m.ertman@...el.com>, Ira Weiny <ira.weiny@...el.com>,
 Leon Romanovsky <leon@...nel.org>, "Rafael J. Wysocki" <rafael@...nel.org>,
 Danilo Krummrich <dakr@...nel.org>, linux-kernel@...r.kernel.org,
 Zijun Hu <zijun.hu@....qualcomm.com>
Subject: Re: [PATCH] driver core: auxiliary bus: Optimize auxiliary_match_id()

On 2025/9/2 20:20, Greg Kroah-Hartman wrote:
> On Tue, Sep 02, 2025 at 08:05:32PM +0800, Zijun Hu wrote:
>> From: Zijun Hu <zijun.hu@....qualcomm.com>
>>
>> Variable @match_size is fixed in auxiliary_match_id().
>>
>> Optimize the function by moving the logic calculating the variable
>> out of the for loop.
> Optimize it how?  Does this actually result in a difference somehow, if
> so, what?
> 

auxiliary_match_id() repeatedly calculates variable @match_size in the
for loop. however, the variable is fixed actually. so it is enough to
calculate the variable once.

Optimize it by moving the logic calculating the variable out of the for
loop, and it result in:

1) calculate the variable once instead of repeatedly.
2) it will return as early as possible if device name is unexpected,
namely, (@p == NULL).

so this fix will improve performance.

> Please be specific.

will give more commit message in v2.

thanks