Messages in this thread | | | Date | Wed, 8 Mar 2006 16:17:33 -0500 | From | Benjamin LaHaise <> | Subject | Re: [patch 1/4] net: percpufy frequently used vars -- add percpu_counter_mod_bh |
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On Wed, Mar 08, 2006 at 01:07:26PM -0800, Ravikiran G Thirumalai wrote: > But on non x86, local_bh_disable() is gonna be cheaper than a cli/atomic op no? > (Even if they were switched over to do local_irq_save() and > local_irq_restore() from atomic_t's that is).
It's still more expensive than local_t.
> And if we use local_t, we will add the overhead for the non bh > percpu_counter_mod for non x86 arches.
Last time I checked, all the major architectures had efficient local_t implementations. Most of the RISC CPUs are able to do a load / store conditional implementation that is the same cost (since memory barriers tend to be explicite on powerpc). So why not use it?
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