[ltt-dev] cli/sti vs local_cmpxchg and local_add_return
compudj at krystal.dyndns.org
Tue Mar 17 15:35:32 EDT 2009
* David Miller (davem at davemloft.net) wrote:
> From: Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>
> Date: Tue, 17 Mar 2009 12:06:35 -0400
> > But powerpc has non-maskable interrupts, so for less than 4 cycles, I
> > think it's better to stay with the local_t variant to be NMI-safe.
> Sparc64 has non-maskable interrupts too btw.
OK, this alone is a strong argument to favor NMI-safe lockless algorithm
even if it is a bit slower. We should see what kind of performance
impact it has on overall tracing performance to find out if it will make
a measurable difference anyway.
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