@SebAaltonen TATAS (read-only inner-loop) is a much better pattern for a multicore system with multiple caches (https://github.com/concurrencykit/ck/blob/master/include/spinlock/fas.h#L77).

Source

• URL: https://x.com/0xF390/status/1125432870510759937
• Author: Samy Al Bahra (@0xF390)
• Posted: 2019-05-06 16:11:20

Branch

1/ @0xF390

@SebAaltonen

TATAS (read-only inner-loop) is a much better pattern for a multicore system with multiple caches (https://github.com/concurrencykit/ck/blob/master/include/spinlock/fas.h#L77).

2/ @SebAaltonen

@0xF390

This is TATAS too. It does standard read until read returns unlocked (|| is short circuited -> exchange doesn’t run when outer test succeeds). Your code has extra CAS outer case. Not needed. Just makes fast path (no lock) slower.

3/ @0xF390

@SebAaltonen

Edits. You’re right! I read the wrong block. Regarding the Concurrency Kit code, which CAS outer-case are you referring to? There is none, FAS = xchg.

Related

• Spine: 2019-05-05-this-is-how-you-write-a-good-x64-spinlock-use-two