linux-kernel - Re: [PATCH 13/35] x86, lmb: Add lmb_free_memory

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Date:	Fri, 14 May 2010 09:37:08 -0700
From:	Yinghai Lu <yinghai.lu@...cle.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.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 13/35] x86, lmb: Add lmb_free_memory_size()

On 05/14/2010 01:21 AM, Benjamin Herrenschmidt wrote:
> On Thu, 2010-05-13 at 23:42 -0700, Yinghai wrote:
>   
>> On 05/13/2010 07:31 PM, Benjamin Herrenschmidt wrote:
>>     
>>> On Thu, 2010-05-13 at 17:19 -0700, Yinghai Lu wrote:
>>>       
>>>> It will return free memory size in specified range.
>>>>
>>>> We can not use memory_size - reserved_size here, because some reserved area
>>>> may not be in the scope of lmb.memory.region.
>>>>
>>>> Use lmb.memory.region subtracting lmb.reserved.region to get free range array.
>>>> then count size of all free ranges.
>>>>         
>>> I remember having already told you that the naming sucks.
>>>       
>> any suggestion?
>>
>> i think this name is clear.
>>     
> Well, I did have suggestions yes. Among others, because you are
> operating on a range, you should have the word "range" in your name. For
> example, something like lmb_free_memory_in_range(). A bit long but at
> least is self explanatory and doesn't lead to confusion.
>   

lmb_memory_size_in_range()/lmb_free_memory_size_in_range()

or

lmb_memory_in_range()/lmb_free_memory_in_range()

?



>  
>   
>>> Also, you fail to explain what this is actually needed for.
>>>       
>> needed by 
>>
>> [PATCH 21/35] x86, lmb: Use lmb_memory_size()/lmb_free_memory_size() to get correct dma_reserve
>>     
> Ok, that's some x86ism that I would need to study more closely, but it's
> fair enough to have those accessors if they are really needed. But
> please, try to make an effort on the naming.
>
> Cheers,
> Ben.
>
>   
>>     
>>> Cheers,
>>> Ben.
>>>
>>>       
>>>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>>>> ---
>>>>  arch/x86/include/asm/lmb.h |    1 +
>>>>  arch/x86/mm/lmb.c          |   51 ++++++++++++++++++++++++++++++++++++++++++++
>>>>  2 files changed, 52 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/arch/x86/include/asm/lmb.h b/arch/x86/include/asm/lmb.h
>>>> index 358d8a6..4fb94b5 100644
>>>> --- a/arch/x86/include/asm/lmb.h
>>>> +++ b/arch/x86/include/asm/lmb.h
>>>> @@ -16,5 +16,6 @@ void lmb_register_active_regions(int nid, unsigned long start_pfn,
>>>>  					 unsigned long last_pfn);
>>>>  u64 lmb_hole_size(u64 start, u64 end);
>>>>  u64 lmb_find_area_node(int nid, u64 start, u64 end, u64 size, u64 align);
>>>> +u64 lmb_free_memory_size(u64 addr, u64 limit);
>>>>  
>>>>  #endif
>>>> diff --git a/arch/x86/mm/lmb.c b/arch/x86/mm/lmb.c
>>>> index c5fa1dd..6c69e99 100644
>>>> --- a/arch/x86/mm/lmb.c
>>>> +++ b/arch/x86/mm/lmb.c
>>>> @@ -226,6 +226,57 @@ void __init lmb_to_bootmem(u64 start, u64 end)
>>>>  }
>>>>  #endif
>>>>  
>>>> +u64 __init lmb_free_memory_size(u64 addr, u64 limit)
>>>> +{
>>>> +	int i, count;
>>>> +	struct range *range;
>>>> +	int nr_range;
>>>> +	u64 final_start, final_end;
>>>> +	u64 free_size;
>>>> +
>>>> +	count = (lmb.reserved.cnt + lmb.memory.cnt) * 2;
>>>> +
>>>> +	range = find_range_array(count);
>>>> +	nr_range = 0;
>>>> +
>>>> +	addr = PFN_UP(addr);
>>>> +	limit = PFN_DOWN(limit);
>>>> +
>>>> +	for (i = 0; i < lmb.memory.cnt; i++) {
>>>> +		struct lmb_region *r = &lmb.memory.regions[i];
>>>> +
>>>> +		final_start = PFN_UP(r->base);
>>>> +		final_end = PFN_DOWN(r->base + r->size);
>>>> +		if (final_start >= final_end)
>>>> +			continue;
>>>> +		if (final_start >= limit || final_end <= addr)
>>>> +			continue;
>>>> +
>>>> +		nr_range = add_range(range, count, nr_range, final_start, final_end);
>>>> +	}
>>>> +	subtract_range(range, count, 0, addr);
>>>> +	subtract_range(range, count, limit, -1ULL);
>>>> +	for (i = 0; i < lmb.reserved.cnt; i++) {
>>>> +		struct lmb_region *r = &lmb.reserved.regions[i];
>>>> +
>>>> +		final_start = PFN_DOWN(r->base);
>>>> +		final_end = PFN_UP(r->base + r->size);
>>>> +		if (final_start >= final_end)
>>>> +			continue;
>>>> +		if (final_start >= limit || final_end <= addr)
>>>> +			continue;
>>>> +
>>>> +		subtract_range(range, count, final_start, final_end);
>>>> +	}
>>>> +	nr_range = clean_sort_range(range, count);
>>>> +
>>>> +	free_size = 0;
>>>> +	for (i = 0; i < nr_range; i++)
>>>> +		free_size += range[i].end - range[i].start;
>>>> +
>>>> +	return free_size << PAGE_SHIFT;
>>>> +}
>>>> +
>>>>  void __init lmb_add_memory(u64 start, u64 end)
>>>>  {
>>>>  	lmb_add_region(&lmb.memory, start, end - start);
>>>>         
>>>       
>> --
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>>     
>
>   

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