linux-kernel - Re: [PATCH 1/1] mm/mlock: implement folio_mlock_step() using folio_pte

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Date: Mon, 3 Jun 2024 04:36:31 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Lance Yang <ioworker0@...il.com>
Cc: akpm@...ux-foundation.org, ryan.roberts@....com, david@...hat.com,
	21cnbao@...il.com, baolin.wang@...ux.alibaba.com, ziy@...dia.com,
	fengwei.yin@...el.com, ying.huang@...el.com, libang.li@...group.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] mm/mlock: implement folio_mlock_step() using
 folio_pte_batch()

On Mon, Jun 03, 2024 at 11:31:17AM +0800, Lance Yang wrote:
>  {
> -	unsigned int count, i, nr = folio_nr_pages(folio);
> -	unsigned long pfn = folio_pfn(folio);
> -	pte_t ptent = ptep_get(pte);

Please don't move type declarations later in the function.  Just because
you can doesn't mean you should.

> -	if (!folio_test_large(folio))
> +	if (likely(!folio_test_large(folio)))
>  		return 1;

How likely is this now?  How likely will it be in two years time?
Does this actually make any difference in either code generation or
performance?