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Date: Mon, 3 Sep 2012 08:27:25 +0300
From: Pekka Enberg <penberg@...nel.org>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
"H. Peter Anvin" <hpa@...or.com>, Jacob Shin <jacob.shin@....com>,
Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -v2 05/13] x86, mm: Find early page table only one time
On Sun, Sep 2, 2012 at 10:46 AM, Yinghai Lu <yinghai@...nel.org> wrote:
> Should not do that in every calling of init_memory_mapping.
> Actually in early time, only need do once.
>
> Also move down early_memtest.
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
The changelog is too terse for my liking. I think it could use some
more context on what the code is actually doing now and why the change
makes it better.
> ---
> arch/x86/mm/init.c | 72 ++++++++++++++++++++++++++-------------------------
> 1 files changed, 37 insertions(+), 35 deletions(-)
>
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index cca9b7d..0ada295 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -37,7 +37,7 @@ struct map_range {
>
> static int page_size_mask;
>
> -static void __init find_early_table_space(struct map_range *mr,
> +static void __init find_early_table_space(unsigned long begin,
> unsigned long end)
> {
> unsigned long puds, pmds, ptes, tables, start = 0, good_end = end;
> @@ -64,8 +64,8 @@ static void __init find_early_table_space(struct map_range *mr,
> extra += PMD_SIZE;
> #endif
> /* The first 2/4M doesn't use large pages. */
> - if (mr->start < PMD_SIZE)
> - extra += mr->end - mr->start;
> + if (begin < PMD_SIZE)
> + extra += (PMD_SIZE - begin) >> PAGE_SHIFT;
>
> ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
> } else
> @@ -265,16 +265,6 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
> nr_range = 0;
> nr_range = split_mem_range(mr, nr_range, start, end);
>
> - /*
> - * Find space for the kernel direct mapping tables.
> - *
> - * Later we should allocate these tables in the local node of the
> - * memory mapped. Unfortunately this is done currently before the
> - * nodes are discovered.
> - */
> - if (!after_bootmem)
> - find_early_table_space(&mr[0], end);
> -
> for (i = 0; i < nr_range; i++)
> ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
> mr[i].page_size_mask);
> @@ -287,6 +277,36 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
>
> __flush_tlb_all();
>
> + return ret >> PAGE_SHIFT;
> +}
> +
> +void __init init_mem_mapping(void)
> +{
> + probe_page_size_mask();
> +
> + /*
> + * Find space for the kernel direct mapping tables.
> + *
> + * Later we should allocate these tables in the local node of the
> + * memory mapped. Unfortunately this is done currently before the
> + * nodes are discovered.
> + */
> +#ifdef CONFIG_X86_64
> + find_early_table_space(0, max_pfn<<PAGE_SHIFT);
> +#else
> + find_early_table_space(0, max_low_pfn<<PAGE_SHIFT);
> +#endif
> + max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<<PAGE_SHIFT);
> + max_pfn_mapped = max_low_pfn_mapped;
> +
> +#ifdef CONFIG_X86_64
> + if (max_pfn > max_low_pfn) {
> + max_pfn_mapped = init_memory_mapping(1UL<<32,
> + max_pfn<<PAGE_SHIFT);
> + /* can we preseve max_low_pfn ?*/
> + max_low_pfn = max_pfn;
> + }
> +#endif
> /*
> * Reserve the kernel pagetable pages we used (pgt_buf_start -
> * pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top)
> @@ -302,32 +322,14 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
> * RO all the pagetable pages, including the ones that are beyond
> * pgt_buf_end at that time.
> */
> - if (!after_bootmem && pgt_buf_end > pgt_buf_start)
> + if (pgt_buf_end > pgt_buf_start)
> x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
> PFN_PHYS(pgt_buf_end));
>
> - if (!after_bootmem)
> - early_memtest(start, end);
> + /* stop the wrong using */
> + pgt_buf_top = 0;
>
> - return ret >> PAGE_SHIFT;
> -}
> -
> -void __init init_mem_mapping(void)
> -{
> - probe_page_size_mask();
> -
> - /* max_pfn_mapped is updated here */
> - max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<<PAGE_SHIFT);
> - max_pfn_mapped = max_low_pfn_mapped;
> -
> -#ifdef CONFIG_X86_64
> - if (max_pfn > max_low_pfn) {
> - max_pfn_mapped = init_memory_mapping(1UL<<32,
> - max_pfn<<PAGE_SHIFT);
> - /* can we preseve max_low_pfn ?*/
> - max_low_pfn = max_pfn;
> - }
> -#endif
> + early_memtest(0, max_pfn_mapped << PAGE_SHIFT);
> }
>
> /*
> --
> 1.7.7
>
> --
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