On Thu, 25 Aug 2011, Peter Zijlstra wrote:

On Thu, 2011-08-18 at 14:40 -0700, Andrew Morton wrote:

quoted

I think I'll apply it, as the call frequency is low (correct?) and the
problem will correct itself as other architectures implement their
atomic this_cpu_foo() operations.

Which leads me to wonder, can anything but x86 implement that this_cpu_*
muck? I doubt any of the risk chips can actually do all this.
Maybe Itanic, but then that seems to be dying fast.

The cpu needs to have an RMW instruction that does something to a
variable relative to a register that points to the per cpu base.

Thats generally possible. The problem is how expensive the RMW is going to
be.

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