Re: [rfc: patch 0/6] scalable fd management

[Dipankar Sarma]

On Wed, Jun 01, 2005 at 04:25:20AM -0700, William Lee Irwin III wrote:
> On Mon, May 30, 2005 at 04:20:42PM +0530, Dipankar Sarma wrote:
> > I would appreciate if someone tests this on an arch without
> > cmpxchg (sparc32??). I intend to run some more tests
> > with preemption enabled and also on ppc64 myself.
> 
> sparc32 SMP is not going to be a good choice for this. By and large
> ll/sc -style architectures don't have explicit cmpxchg instructions so
> ppc64 at least nominally fits the bill. SMP Alpha testing may also be
> enlightening (as usual).

Actually, I was talking about cmpxchg() primitive in the kernel,
not necessarily the instruction. ppc64 has a cmpxchg() primitive
based on LL/SC. For the archs that do not have cmpxchg(),
rcuref_inc_lf() uses a hashed lock to serialize the reference
count updates. It would be nice to see that code get a spin
on real hardware. AFAICS, sparc32 fits the bill.

Thanks
Dipankar
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