Re: [PATCH 2/6] change alloc function in pcpu_alloc_pages

[Tejun Heo <tj@kernel.org>]

Hello,

On 04/15/2010 10:31 AM, Minchan Kim wrote:
> Hi, Tejun.
>> This being a pretty cold path, I don't really see much benefit in
>> converting it to alloc_pages_node_exact().  It ain't gonna make any
>> difference.  I'd rather stay with the safer / boring one unless
>> there's a pressing reason to convert.
> 
> Actually, It's to weed out not-good API usage as well as some
> performance gain.  But I don't think to need it strongly.
> Okay. Please keep in mind about this and correct it if you confirms
> it in future. :)

Hmm... if most users are converting over to alloc_pages_node_exact(),
I think it would be better to convert percpu too.  I thought it was a
performance optimization (of rather silly kind too).  So, this is to
weed out -1 node id usage?  Wouldn't it be better to update
alloc_pages_node() such that it whines once per each caller if it's
called with -1 node id and after updating most users convert the
warning into WARN_ON_ONCE()?  Having two variants for this seems
rather extreme to me.

Thanks.

-- 
tejun