Re: [PATCH] percpu: add optimized generic percpu accessors

From: David Miller
Date: Tue Jan 27 2009 - 16:48:10 EST


From: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Date: Tue, 27 Jan 2009 15:08:57 -0500 (EST)

> On Tue, 27 Jan 2009, Tejun Heo wrote:
>
> > > later). That's because they use TLB tricks for a static 64k per-cpu
> > > area, but this doesn't scale. That might not be vital: abandoning
> > > that trick will mean they can't optimise read_percpu/read_percpu_var
> > > etc as much.
>
> Why wont it scale? this is a separate TLB entry for each processor.

The IA64 per-cpu TLB entry only covers 64k which makes use of it for
dynamic per-cpu stuff out of the question. That's why it "doesn't
scale"
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