Re: [patch] kmalloc_percpu -- 2 of 2

[Dipankar Sarma <dipankar@in.ibm.com>]

On Wed, Dec 04, 2002 at 11:34:35AM -0800, Andrew Morton wrote:
> > +/* Use these with kmalloc_percpu */
> > +#define get_cpu_ptr(ptr) per_cpu_ptr(ptr, get_cpu())
> > +#define put_cpu_ptr(ptr) put_cpu()
> 
> These names sound very much like get_cpu_var() and put_cpu_var(),
> yet they are using a quite different subsystem.  It would be good
> to choose something more distinct.  Not that I can think of anything
> at present ;)

Well, they are similar, aren't they ? get_cpu_ptr() can just be thought
of as the dynamic twin of get_cpu_var(). So, in that sense it seems ok
to me.

> 
> If we were to remove the percpu_interlaced_alloc() leg here, we'd
> have a nice, simple per-cpu kmalloc implementation.
> 
> Could you please explain what all the other code is there for?

The interlaced allocator allows you to save space when kmalloc_percpu()
is used to allocate small objects. That is done by interlacing each
CPU's copy of the objects just like the static per-cpu data area.

Thanks
-- 
Dipankar Sarma  <dipankar@in.ibm.com> http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.