Re: [PATCH] percpu: add optimized generic percpu accessors

[Herbert Xu]

Ingo Molnar <mingo@xxxxxxx> wrote:
>
>> Of course.  But do any architectures actually _need_ that for a single 
>> read?
> 
> not for a read i guess - but for the other ops like add/and/or/xor.

One of the things I'd like to see happen with this work is for
us to have a cheap per-cpu atomic counter that we can use for
SNMP stats.

If we can make the inc/add variants into a single instruction,
then it won't need to disable preemption or interrupts.

So if you could design the API such that we have a variant of
add/inc that automatically disables/enables preemption then we
can optimise that away on x86.

Thanks,
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