linux-kernel - Re: [PATCH 1/4] mm: pass set_count and set_reserved to __init_single

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Message-ID: <ZQ1Gg533lODfqvWd@casper.infradead.org>
Date:   Fri, 22 Sep 2023 08:47:15 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Yajun Deng <yajun.deng@...ux.dev>
Cc:     akpm@...ux-foundation.org, mike.kravetz@...cle.com,
        muchun.song@...ux.dev, glider@...gle.com, elver@...gle.com,
        dvyukov@...gle.com, rppt@...nel.org, david@...hat.com,
        osalvador@...e.de, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com
Subject: Re: [PATCH 1/4] mm: pass set_count and set_reserved to
 __init_single_page

On Fri, Sep 22, 2023 at 03:09:20PM +0800, Yajun Deng wrote:
> -		__init_single_page(page, pfn, zone, nid);
> +		__init_single_page(page, pfn, zone, nid, true, false);

So Linus has just had a big rant about not doing bool flags to
functions.  And in particular _multiple_ bool flags to functions.

ie this should be:

#define INIT_PAGE_COUNT		(1 << 0)
#define INIT_PAGE_RESERVED	(1 << 1)

		__init_single_page(page, pfn, zone, nid, INIT_PAGE_COUNT);

or something similar.

I have no judgement on the merits of this patch so far.  Do you have
performance numbers for each of these patches?  Some of them seem quite
unlikely to actually help, at least on a machine which is constrained
by cacheline fetches.