linux-kernel - Re: [PATCH v8 06/46] x86, mm: Change find_early_table

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Message-ID: <20121128165007.GE21266@phenom.dumpdata.com>
Date:	Wed, 28 Nov 2012 11:50:07 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
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>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 06/46] x86, mm: Change find_early_table_space()
 paramters


s/paramters/parameters/

On Fri, Nov 16, 2012 at 07:38:43PM -0800, Yinghai Lu wrote:
> call split_mem_range inside the function.

So this looks to introduce an extra split_mem_range which
does the same operations on 'mr' that is done in find_early_table_space.

Could the find_early_table_space use the init_memory_mapping
'mr' and 'nr_range'?

This is the call chain:
	nr_range = split_mem_range(mr, nr_range, start, end)

	..
	if (!after_bootmem)
		find_early_table_space(..)
			nr_rnage = split_mem_range(mr, nr_range, start, end)

Perhaps you could modify find_early_table_space to just return
the nr_range (and also use the 'mr')?

And then you would do:

	if (!after_bootmem)
		nr_range = find_early_table_space(..)
	else {
		memset(mr, 0, sizeof(mr));
        	nr_range = split_mem_range(mr, 0, start, end);
	}


Ah, I see you redid this in the next patch. Can you then point
this out in the commit description please? Say:

"The patch: x86, mm: Find early page table buffer together
tidies this up so we do not end up calling split_mem_range twice."


> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---
>  arch/x86/mm/init.c |   12 +++++++++---
>  1 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index dbef4ff..51f919f 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -196,12 +196,18 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range,
>   * mr[0].start to mr[nr_range - 1].end, while accounting for possible 2M and 1GB
>   * pages. Then find enough contiguous space for those page tables.
>   */
> -static void __init find_early_table_space(struct map_range *mr, int nr_range)
> +static void __init find_early_table_space(unsigned long start, unsigned long end)
>  {
>  	int i;
>  	unsigned long puds = 0, pmds = 0, ptes = 0, tables;
> -	unsigned long start = 0, good_end;
> +	unsigned long good_end;
>  	phys_addr_t base;
> +	struct map_range mr[NR_RANGE_MR];
> +	int nr_range;
> +
> +	memset(mr, 0, sizeof(mr));
> +	nr_range = 0;
> +	nr_range = split_mem_range(mr, nr_range, start, end);
>  
>  	for (i = 0; i < nr_range; i++) {
>  		unsigned long range, extra;
> @@ -276,7 +282,7 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
>  	 * nodes are discovered.
>  	 */
>  	if (!after_bootmem)
> -		find_early_table_space(mr, nr_range);
> +		find_early_table_space(start, end);
>  
>  	for (i = 0; i < nr_range; i++)
>  		ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
> -- 
> 1.7.7
--
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