Re: [Lhms-devel] [RFC] buddy allocator without bitmap [2/4]

[Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com>]

Hi

I understand using these macros cleans up codes as I used them in my previous
version.

In the previous version, I used SetPagePrivate()/ClearPagePrivate()/PagePrivate().
But these are "atomic" operation and looks very slow.
This is why I doesn't used these macros in this version.

My previous version, which used set_bit/test_bit/clear_bit, shows very bad performance
on my test, and I replaced it.

If I made a mistake on measuring the performance and set_bit/test_bit/clear_bit
is faster than what I think, I'd like to replace them.

-- Kame

Dave Hansen wrote:
> On Thu, 2004-08-26 at 05:03, Hiroyuki KAMEZAWA wrote:
> 
>>-		MARK_USED(index + size, high, area);
>>+		page[size].flags |= (1 << PG_private);
>>+		page[size].private = high;
>>  	}
>>  	return page;
>>  }
> 
> ...
> 
>>+		/* Atomic operation is needless here */
>>+		page->flags &= ~(1 << PG_private);
> 
> 
> See linux/page_flags.h:
> 
> #define SetPagePrivate(page)    set_bit(PG_private, &(page)->flags)
> #define ClearPagePrivate(page)  clear_bit(PG_private, &(page)->flags)
> #define PagePrivate(page)       test_bit(PG_private, &(page)->flags)
> 
> -- Dave
> 
> 


-- 
--the clue is these footmarks leading to the door.--
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

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