Messages in this thread | | | Date | Wed, 30 Sep 2009 19:49:50 -0400 (EDT) | From | Christoph Lameter <> | Subject | Re: [PATCHSET percpu#for-next] percpu: convert ia64 to dynamic percpu and drop the old one, take#2 |
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On Thu, 1 Oct 2009, Peter Chubb wrote:
> r3, r4 and r5 are currently unused by the kernel, and unused > by GCC and ICC. Only hand-written assembler and weird compilers use > those registers(and my virtual-machine monitor :-(). If you wanted to > experiment, that'd be a starting place. > > I'm not sure of the advantage though -- TLB mapping is relatively > cheap, and we're no longer hard-wiring the translation register.
Dynamic and static per cpu variables could use relative access to that register. This would reduce code size, avoid the use of a TLB entry.
> You';d have to do somne careful benchmarking on a wide variety of > workloads and machines to get a definitive answer.
I have some patches here that make heavy use of dynamic percpu allocations in the allocators to optimize the alloc / free paths.
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