Re: [GIT RFC] percpu: use dynamic percpu allocator as the default percpu allocator

Tejun Heo
2009-04-02T01:55:49Z

Hello,

Martin Schwidefsky wrote:
>> Also, there is no guarantee that the offset from dynamic allocator
>> will fall in the same 4G. There is reserve mechanism for static ones
>> for archs which need it but for dynamic ones, the offset can be any
>> value.
>
> If we map the modules with a 4GB distance to the main kernel image then
> we don't have to worry about the offsets anymore. The compiler could
> just use LARL to get the address of the static per-cpu variables and
> SHIFT_PERCPU_PTR could be a RELOC_HIDE.

Ah... okay. Great. No more GOTENT trick for static ones and for
dynamic ones the compiler will generate indirection.

> It just that the remapping we need to do is sooo icky ..

Fingers and toes crossed. It would improve general percpu access
performance too.

Thanks.

--
tejun