Re: [GIT PATCH] x86,percpu: fix pageattr handling with remap allocator

Suresh Siddha
2009-05-21T00:38:17Z

On Wed, 2009-05-20 at 17:08 -0700, Tejun Heo wrote:
> Heh... the problem is that unless I understand what you're trying to
> achieve (and vice-versa), our discussion is likely to be riddled with
> confusions, and currently either you're misunderstanding the whole
> thing or I'm being slow (not too unusual :-). It would be nice to
> determine which way it is.

At the start of this, I was trying to see a way where we can use large
page mappings for percpu areas and at the same time, avoid the
complexity of cpa() that we are adding in this patchset. So, I was going
down the path of exploiting your bootmem allocation for the first percpu
chunk (as kernel identity mappings are already taken care by cpa()).

> The dynamic onlining will probably use 4k pages so, yeah, it won't
> have the alias issues but that's not the issue here, right? You can
> already avoid aliasing that way by simply using 4k allocator from the
> get-go.

But now that I learnt about dynamic online allocation, can we avoid the
complexity brought by this patchset, by simply using 4k allocator from
get-go.

i.e., can we drop this remap pageattr handling patchset and simply use
4k mapping for now? And move to dynamic allocation at a later point.

This will simplify quite a bit of code.

thanks,
suresh