Re: [PATCH v1] mm/readahead: Optimize nr_to_read boundary check

["Xiaole He" <hexiaole1994@126.com>]

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Thanks for your quick review and feedback.
I understand your points regarding the minimal performance impact and
the preference for keeping the current logic given its long-standing
correctness. I agree that the change is indeed minor in scope.
No worries at all, I appreciate you taking the time to consider the
patch.
Best regards,  


| |
Xiaole He
|
|
hexiaole1994@126.com
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---- Replied Message ----
| From | Matthew Wilcox<willy@infradead.org> |
| Date | 7/25/2025 23:45 |
| To | Xiaole He<hexiaole1994@126.com> |
| Cc | Andrew Morton<akpm@linux-foundation.org>,
<linux-fsdevel@vger.kernel.org>,
<linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org> |
| Subject | Re: [PATCH v1] mm/readahead: Optimize nr_to_read boundary check |
On Fri, Jul 25, 2025 at 11:28:34PM +0800, Xiaole He wrote:
If nr_to_read is, for instance, 3, and end_index - index + 1 is also 3
 (meaning 3 pages remain), the condition 3 > 2 evaluates to true, leading
  to nr_to_read being assigned 3 again. While compilers might optimize
 this trivial self-assignment, it introduces unnecessary logical overhead
  and reduces code clarity.

But it makes the initial comparison more complex (by one operation) and
I bet you can't measure the difference anyway.  I'm not inclined to
tweak this.

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