Re: [PATCH RFC] x86: avoid atomic operation in test_and_set_bit_lock if possible

[Andi Kleen]

Nikanth Karthikesan <knikanth@xxxxxxx> writes:

> On x86_64 SMP with lots of CPU atomic instructions which assert the LOCK #
> signal can stall other CPUs. And as the number of cores increase this penalty

This description is very wrong. No modern CPU still has a LOCK # signal
or does global stalls for LOCK.

Do you actually have any data this is a problem and how much
difference the patch makes?

Also there's the missing barrier now of course.

-Andi
-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only
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