On Sun, Jul 25, 2021 at 5:06 AM Jiaxun Yang [off-list ref] wrote:

在 2021/7/25 上午3:24, Arnd Bergmann 写道:

quoted

- If I remember correctly, there were some concerns about whether using
   this information for picking the qspinlock implementation is a good idea.

We've checked previous attempt made by Guo Ren about
ARCH_USE_QUEUED_SPINLOCKS_XCHG32[1], the concerns of potential livelock
do exist.

So in this patch Huacai took another, dropping the whole standalone
tailing logic to remove the usage of sub-word xchg. It could be understood as
partial revert of 69f9cae9 ("locking/qspinlock: Optimize for smaller NR_CPUS")
[2] on these architectures.

Ok, I see. Let's see what Peter thinks about it.

        Arnd