linux-kernel - Re: [PATCH 09/28] nios2: Page table management

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Message-ID: <20140419160552.GA19577@amd.pavel.ucw.cz>
Date:	Sat, 19 Apr 2014 18:05:53 +0200
From:	Pavel Machek <pavel@...x.de>
To:	Ley Foon Tan <lftan@...era.com>
Cc:	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, lftan.linux@...il.com,
	cltang@...esourcery.com
Subject: Re: [PATCH 09/28] nios2: Page table management

Hi!

> This patch adds support for page table management.
> 
> Signed-off-by: Ley Foon Tan <lftan@...era.com>

> +/*
> + * Initialize a new pgd / pmd table with invalid pointers.
> + */
> +static void pgd_init(pgd_t *pgd)
> +{
> +	unsigned long *p = (unsigned long *) pgd;
> +	int i;
> +
> +	for (i = 0; i < USER_PTRS_PER_PGD; i += 8) {
> +		p[i + 0] = (unsigned long) invalid_pte_table;
> +		p[i + 1] = (unsigned long) invalid_pte_table;
> +		p[i + 2] = (unsigned long) invalid_pte_table;
> +		p[i + 3] = (unsigned long) invalid_pte_table;
> +		p[i + 4] = (unsigned long) invalid_pte_table;
> +		p[i + 5] = (unsigned long) invalid_pte_table;
> +		p[i + 6] = (unsigned long) invalid_pte_table;
> +		p[i + 7] = (unsigned long) invalid_pte_table;
> +	}

Umm. Manual loop unrolling. Does it really improve performance? Is the
code hot enough to warrant the uglyness?

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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