(2012/06/18 22:19), Wanpeng Li wrote:

On Mon, Jun 18, 2012 at 05:09:36PM +0400, Glauber Costa wrote:

quoted

On 06/18/2012 05:10 PM, Wanpeng Li wrote:

quoted

From: Wanpeng Li<redacted>

move_charge_at_immigrate feature is disabled by default. Charges
are moved only when you move mm->owner and it also add additional
overhead.

How big is this overhead?

That's hardly a fast path. And if it happens to matter, it will be
just bigger when you enable it, and the compiler start giving the
wrong hints to the code.

Thank you for your quick response.

Oh, Maybe I should just write comments "move_charge_at_immigrate feature
is disabled by default. So add "unlikely", in order to compiler can optimize."

This doesn't affect the performance. likely/unlikely which doesn't affect
performance is never welcomed.

Thanks,
-Kame