Memory allocation question

Memory allocation question

[george anzinger]

I need (want) to allocate block of memory for POSIX timers in about page
size chuncks.  Currently I am using kmalloc() to allocate a page at a
time.  I don't want to have to worry about mapping/unmapping etc.  I
just what to go about using the memory.  It will be used for timers so
it must not be paged.  

Is kmalloc() the best interface to use or is there a better one?


-- 
George           george@mvista.com
High-res-timers: http://sourceforge.net/projects/high-res-timers/
Real time sched: http://sourceforge.net/projects/rtsched/

Re: Memory allocation question

[Alan Cox]

> size chuncks.  Currently I am using kmalloc() to allocate a page at a
> time.  I don't want to have to worry about mapping/unmapping etc.  I

Use get_free_page() to get page sized chunks

Re: Memory allocation question

[george anzinger]

Alan Cox wrote:
> 
> > size chuncks.  Currently I am using kmalloc() to allocate a page at a
> > time.  I don't want to have to worry about mapping/unmapping etc.  I
> 
> Use get_free_page() to get page sized chunks

What about __get_free_page() ?  I don't need or want the clear page
(performance issues).

And then to return the page, free_page() ?

-- 
George           george@mvista.com
High-res-timers: http://sourceforge.net/projects/high-res-timers/
Real time sched: http://sourceforge.net/projects/rtsched/

Re: Memory allocation question

[Rik van Riel]

On Wed, 21 Nov 2001, george anzinger wrote:
> Alan Cox wrote:
> >
> > > size chuncks.  Currently I am using kmalloc() to allocate a page at a
> > > time.  I don't want to have to worry about mapping/unmapping etc.  I
> >
> > Use get_free_page() to get page sized chunks
>
> What about __get_free_page() ?  I don't need or want the clear page
> (performance issues).

get_free_page() doesn't clear the page afaics.

regards,

Rik
-- 
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Re: Memory allocation question

[george anzinger]

Rik van Riel wrote:
> 
> On Wed, 21 Nov 2001, george anzinger wrote:
> > Alan Cox wrote:
> > >
> > > > size chuncks.  Currently I am using kmalloc() to allocate a page at a
> > > > time.  I don't want to have to worry about mapping/unmapping etc.  I
> > >
> > > Use get_free_page() to get page sized chunks
> >
> > What about __get_free_page() ?  I don't need or want the clear page
> > (performance issues).
> 
> get_free_page() doesn't clear the page afaics.
> 
In mm.h (2.4.13 kernel)....

#define __get_free_page(gfp_mask) \
		__get_free_pages((gfp_mask),0)

#define __get_dma_pages(gfp_mask, order) \
		__get_free_pages((gfp_mask) | GFP_DMA,(order))

/*
 * The old interface name will be removed in 2.5:
 */
#define get_free_page get_zeroed_page
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Where as __get_free_page() does not zero.  I know this is an old kernel,
but...


What am I missing?
-- 
George           george@mvista.com
High-res-timers: http://sourceforge.net/projects/high-res-timers/
Real time sched: http://sourceforge.net/projects/rtsched/

Re: Memory allocation question

[Rik van Riel]

On Wed, 21 Nov 2001, george anzinger wrote:

> /*
>  * The old interface name will be removed in 2.5:
>  */
> #define get_free_page get_zeroed_page
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> Where as __get_free_page() does not zero.  I know this is an old
> kernel, but...

Urghhh, you're right.

Rik
-- 
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http://www.surriel.com/		http://distro.conectiva.com/