Re: [PATCH] percpu_counter : add percpu_counter_add_fast()

[Andrew Morton]

On Sat, 16 Oct 2010 16:19:14 +0200
Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:

> The current way to change a percpu_counter is to call
> percpu_counter_add(), which is a bit expensive.
> (More than 40 instructions, possible false sharing, ...)

This is incorrect.  With my compiler it's 25 instructions except in the
very rare case where a batch overflow occurs.

And more than half of that is function call entry/exit overhead.

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