linux-kernel - Re: [PATCH 07/39] lmb: Add lmb_find

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Date:	Tue, 13 Apr 2010 14:05:43 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Miller <davem@...emloft.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 07/39] lmb: Add lmb_find_area()

On Thu, 2010-04-08 at 23:03 -0700, Yinghai Lu wrote:
> It will try find area according with size/align in specified range (start, end).
> 
> lmb_find_area() will honor goal/limit.
> 
> also make it more easy for x86 to use lmb.
> x86 early_res is using find/reserve pattern instead of alloc.
> 
> When we need temporaray buff for range array etc for range work, if We are using
> lmb_alloc(), We will need to add some post fix code for buffer that is used
> by range array, because it is in the lmb.reserved already. and have to call
> extra lmb_free().
> 
> -v2: Change name to lmb_find_area() according to Michael Ellerman
> -v3: Add generic weak version __lmb_find_area()

Haven't you noticed there's already way too many functions walking the
LMBs ? :-)

I think the ones doing nid alloc could/should be also rewritten to use
one single low level __lmb_find_* no ?

Cheers,
Ben.

> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---
>  include/linux/lmb.h |    4 ++++
>  mm/lmb.c            |   49 +++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 53 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/lmb.h b/include/linux/lmb.h
> index e14ea8d..4cf2f3b 100644
> --- a/include/linux/lmb.h
> +++ b/include/linux/lmb.h
> @@ -83,6 +83,10 @@ lmb_end_pfn(struct lmb_region *type, unsigned long region_nr)
>  	       lmb_size_pages(type, region_nr);
>  }
>  
> +u64 __lmb_find_area(u64 ei_start, u64 ei_last, u64 start, u64 end,
> +			 u64 size, u64 align);
> +u64 lmb_find_area(u64 start, u64 end, u64 size, u64 align);
> +
>  #include <asm/lmb.h>
>  
>  #endif /* __KERNEL__ */
> diff --git a/mm/lmb.c b/mm/lmb.c
> index 392d805..7010212 100644
> --- a/mm/lmb.c
> +++ b/mm/lmb.c
> @@ -11,9 +11,13 @@
>   */
>  
>  #include <linux/kernel.h>
> +#include <linux/types.h>
>  #include <linux/init.h>
>  #include <linux/bitops.h>
>  #include <linux/lmb.h>
> +#include <linux/bootmem.h>
> +#include <linux/mm.h>
> +#include <linux/range.h>
>  
>  #define LMB_ALLOC_ANYWHERE	0
>  
> @@ -559,3 +563,48 @@ int lmb_find(struct lmb_property *res)
>  	}
>  	return -1;
>  }
> +
> +u64 __init __weak __lmb_find_area(u64 ei_start, u64 ei_last, u64 start, u64 end,
> +				 u64 size, u64 align)
> +{
> +	u64 final_start, final_end;
> +	u64 mem;
> +
> +	final_start = max(ei_start, start);
> +	final_end = min(ei_last, end);
> +
> +	if (final_start >= final_end)
> +		return -1ULL;
> +
> +	mem = __lmb_find_base(size, align, final_end);
> +
> +	if (mem == -1ULL)
> +		return -1ULL;
> +
> +	lmb_free(mem, size);
> +	if (mem >= final_start)
> +		return mem;
> +
> +	return -1ULL;
> +}
> +
> +/*
> + * Find a free area with specified alignment in a specific range.
> + */
> +u64 __init __weak lmb_find_area(u64 start, u64 end, u64 size, u64 align)
> +{
> +	int i;
> +
> +	for (i = lmb.memory.cnt - 1; i >= 0; i--) {
> +		u64 ei_start = lmb.memory.region[i].base;
> +		u64 ei_last = ei_start + lmb.memory.region[i].size;
> +		u64 addr;
> +
> +		addr = __lmb_find_area(ei_start, ei_last, start, end,
> +					 size, align);
> +
> +		if (addr != -1ULL)
> +			return addr;
> +	}
> +	return -1ULL;
> +}


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