Re: [PATCH] hugetlb, x86: register 1G page size if we can allocate them runtime

From: Luiz Capitulino
Date: Wed Feb 04 2015 - 12:47:23 EST


On Wed, 4 Feb 2015 13:54:31 +0200
"Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote:

> After commit 944d9fec8d7a we can allocate 1G pages runtime if CMA is
> enabled.
>
> Let's register 1G pages into hugetlb even if user hasn't requested them
> explicitly at boot time with hugepagesz=1G.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> ---
> arch/x86/mm/hugetlbpage.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
> index 9161f764121e..42982b26e32b 100644
> --- a/arch/x86/mm/hugetlbpage.c
> +++ b/arch/x86/mm/hugetlbpage.c
> @@ -172,4 +172,15 @@ static __init int setup_hugepagesz(char *opt)
> return 1;
> }
> __setup("hugepagesz=", setup_hugepagesz);
> +
> +#ifdef CONFIG_CMA
> +static __init int gigantic_pages_init(void)
> +{
> + /* With CMA we can allocate gigantic pages at runtime */
> + if (cpu_has_gbpages && !size_to_hstate(1UL << PUD_SHIFT))
> + hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
> + return 0;
> +}
> +arch_initcall(gigantic_pages_init);
> +#endif
> #endif

Very nice! I was thinking about this for a long time but I don't
think my implementation would be that simple:

Reviewed-by: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
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