[PATCH] page-allocator: Remove dead function free_cold_page()

[PATCH] page-allocator: Remove dead function free_cold_page()

[Mel Gorman]

The function free_cold_page() has no callers so delete it.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
--- 
 include/linux/gfp.h |    1 -
 mm/page_alloc.c     |    5 -----
 2 files changed, 6 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 7c777a0..c32bfa8 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -326,7 +326,6 @@ void free_pages_exact(void *virt, size_t size);
 extern void __free_pages(struct page *page, unsigned int order);
 extern void free_pages(unsigned long addr, unsigned int order);
 extern void free_hot_page(struct page *page);
-extern void free_cold_page(struct page *page);
 
 #define __free_page(page) __free_pages((page), 0)
 #define free_page(addr) free_pages((addr),0)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d052abb..36758db 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1065,11 +1065,6 @@ void free_hot_page(struct page *page)
 	free_hot_cold_page(page, 0);
 }
 	
-void free_cold_page(struct page *page)
-{
-	free_hot_cold_page(page, 1);
-}
-
 /*
  * split_page takes a non-compound higher-order page, and splits it into
  * n (1<<order) sub-pages: page[0..n]

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Re: [PATCH] page-allocator: Remove dead function free_cold_page()

[Andrew Morton]

On Wed, 5 Aug 2009 11:28:17 +0100 Mel Gorman <mel@csn.ul.ie> wrote:

> The function free_cold_page() has no callers so delete it.
> 
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> --- 
>  include/linux/gfp.h |    1 -
>  mm/page_alloc.c     |    5 -----
>  2 files changed, 6 deletions(-)
> 
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 7c777a0..c32bfa8 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -326,7 +326,6 @@ void free_pages_exact(void *virt, size_t size);
>  extern void __free_pages(struct page *page, unsigned int order);
>  extern void free_pages(unsigned long addr, unsigned int order);
>  extern void free_hot_page(struct page *page);
> -extern void free_cold_page(struct page *page);
>  
>  #define __free_page(page) __free_pages((page), 0)
>  #define free_page(addr) free_pages((addr),0)
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d052abb..36758db 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1065,11 +1065,6 @@ void free_hot_page(struct page *page)
>  	free_hot_cold_page(page, 0);
>  }
>  	
> -void free_cold_page(struct page *page)
> -{
> -	free_hot_cold_page(page, 1);
> -}
> -
>  /*
>   * split_page takes a non-compound higher-order page, and splits it into
>   * n (1<<order) sub-pages: page[0..n]

Well I spose so.  But the function is valid and might need to be
resurrected at any stage.  We could `#if 0' it to save a few bytes of
text, perhaps.

I wonder how many free_page() callers should really be calling
free_cold_page().  c'mon, write a thingy to work it out ;) You can
query a page's hotness by timing how long it takes to read all its
cachelines.


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Re: [PATCH] page-allocator: Remove dead function free_cold_page()

[KOSAKI Motohiro]

2009/8/6 Andrew Morton <akpm@linux-foundation.org>:
> On Wed, 5 Aug 2009 11:28:17 +0100 Mel Gorman <mel@csn.ul.ie> wrote:
>
>> The function free_cold_page() has no callers so delete it.
>>
>> Signed-off-by: Mel Gorman <mel@csn.ul.ie>
>> ---
>>  include/linux/gfp.h |    1 -
>>  mm/page_alloc.c     |    5 -----
>>  2 files changed, 6 deletions(-)
>>
>> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
>> index 7c777a0..c32bfa8 100644
>> --- a/include/linux/gfp.h
>> +++ b/include/linux/gfp.h
>> @@ -326,7 +326,6 @@ void free_pages_exact(void *virt, size_t size);
>>  extern void __free_pages(struct page *page, unsigned int order);
>>  extern void free_pages(unsigned long addr, unsigned int order);
>>  extern void free_hot_page(struct page *page);
>> -extern void free_cold_page(struct page *page);
>>
>>  #define __free_page(page) __free_pages((page), 0)
>>  #define free_page(addr) free_pages((addr),0)
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index d052abb..36758db 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -1065,11 +1065,6 @@ void free_hot_page(struct page *page)
>>       free_hot_cold_page(page, 0);
>>  }
>>
>> -void free_cold_page(struct page *page)
>> -{
>> -     free_hot_cold_page(page, 1);
>> -}
>> -
>>  /*
>>   * split_page takes a non-compound higher-order page, and splits it into
>>   * n (1<<order) sub-pages: page[0..n]
>
> Well I spose so.  But the function is valid and might need to be
> resurrected at any stage.  We could `#if 0' it to save a few bytes of
> text, perhaps.
>
> I wonder how many free_page() callers should really be calling
> free_cold_page().  c'mon, write a thingy to work it out ;) You can
> query a page's hotness by timing how long it takes to read all its
> cachelines.

if we decide to keep this function, I think we also need to consider
make it exporting.
Driver developers never user unexported function.

Or, Can we free_hot_page() and free_cold_page move to inlined function?

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Re: [PATCH] page-allocator: Remove dead function free_cold_page()

[Mel Gorman]

On Wed, Aug 05, 2009 at 06:52:47PM -0700, Andrew Morton wrote:
> On Wed, 5 Aug 2009 11:28:17 +0100 Mel Gorman <mel@csn.ul.ie> wrote:
> 
> > The function free_cold_page() has no callers so delete it.
> > 
> > Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> > --- 
> >  include/linux/gfp.h |    1 -
> >  mm/page_alloc.c     |    5 -----
> >  2 files changed, 6 deletions(-)
> > 
> > diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> > index 7c777a0..c32bfa8 100644
> > --- a/include/linux/gfp.h
> > +++ b/include/linux/gfp.h
> > @@ -326,7 +326,6 @@ void free_pages_exact(void *virt, size_t size);
> >  extern void __free_pages(struct page *page, unsigned int order);
> >  extern void free_pages(unsigned long addr, unsigned int order);
> >  extern void free_hot_page(struct page *page);
> > -extern void free_cold_page(struct page *page);
> >  
> >  #define __free_page(page) __free_pages((page), 0)
> >  #define free_page(addr) free_pages((addr),0)
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index d052abb..36758db 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -1065,11 +1065,6 @@ void free_hot_page(struct page *page)
> >  	free_hot_cold_page(page, 0);
> >  }
> >  	
> > -void free_cold_page(struct page *page)
> > -{
> > -	free_hot_cold_page(page, 1);
> > -}
> > -
> >  /*
> >   * split_page takes a non-compound higher-order page, and splits it into
> >   * n (1<<order) sub-pages: page[0..n]
> 
> Well I spose so.  But the function is valid and might need to be
> resurrected at any stage.  We could `#if 0' it to save a few bytes of
> text, perhaps.
> 

We could although the code is so trivial, it's not like it's hard to
reimplement.

> I wonder how many free_page() callers should really be calling
> free_cold_page().  c'mon, write a thingy to work it out ;) You can
> query a page's hotness by timing how long it takes to read all its
> cachelines.
> 

Hmm, interesting idea, I'll give it more of a think and see what falls
out!

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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