Re: [patch 0/7] [RFC] SLUB: Improve allocpercpu to reduce per cpu access overhead

Peter Zijlstra
2007-11-02T10:29:08Z

On Thu, 2007-11-01 at 15:58 -0700, David Miller wrote:

> Since you're the one who wants to change the semantics and guarentees
> of this interface, perhaps it might help if you did some greps around
> the tree to see how alloc_percpu() is actually used. That's what
> I did when I started running into trouble with your patches.

This fancy new BDI stuff also lives off percpu_counter/alloc_percpu().

That means that for example each NFS mount also consumes a number of
words - not quite sure from the top of my head how many, might be in the
order of 24 bytes or something.

I once before started looking at this, because the current
alloc_percpu() can have some false sharing - not that I have machines
that are overly bothered by that. I like the idea of a strict percpu
region, however do be aware of the users.