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

Andi Kleen
2011-03-24T18:39:57Z

Nikanth Karthikesan <knikanth@suse.de> 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@linux.intel.com -- Speaking for myself only