Re: [PATCH UPDATED] percpu: use dynamic percpu allocator as the default percpu allocator

Tejun Heo
2009-04-01T00:18:54Z

Hello,

Christoph Lameter wrote:
> I reviewed the new per cpu allocator. Quite extensive work. Found two
> issues that I would like to have addressed. But basically:
>
> Reviewed-by: Christoph Lameter <cl@linux.com>

Thanks.

> Two issues
>
> 1. Lot of unnecessary use of __read_mostly for local static variables that
> are not on the hotpath. Patch follows in this message.

Hmmm... Those are basically read-only vars once initialization is
complete. IIUC, __read_mostly just puts the tagged variables into a
separate segment so that they don't have to worry about cacheline
bouncing. Is there any reason to remove __read_mostly? Or is it just
that it's mostly superflous?

> 2. rbtree is not necessary since we can link back through the an available
> field in struct page. Patch in next message.

Ah... nice. I was thinking about adding ->private pointer to the
vmalloc structure but if page already has the space, all the better.

Thanks.

--
tejun