On 07/22/24 at 10:53am, Uros Bizjak wrote: > On Mon, Jul 22, 2024 at 5:09 AM Baoquan He <bhe@xxxxxxxxxx> wrote: > > > > On 07/19/24 at 12:38pm, Uros Bizjak wrote: > > > Use atomic_try_cmpxchg_acquire(*ptr, &old, new) instead of > > > atomic_cmpxchg_acquire(*ptr, old, new) == old in kexec_trylock(). > > > x86 CMPXCHG instruction returns success in ZF flag, so > > > this change saves a compare after cmpxchg. > > > > Seems it can simplify code even though on non-x86 arch, should we > > replace atomic_try_cmpxchg_acquire() with atomic_try_cmpxchg_acquire() > > in all similar places? > > Yes, the change is beneficial also for non-x86 architectures, please > see analysis at thread [1]. I've been looking through the kernel > sources for these places for quite some time, and I believe I have > changed most of the places. The change is relatively straightforward, > and immediately results in a better code. > > [1] https://lore.kernel.org/lkml/871qwgmqws.fsf@xxxxxxxxxxxxxxxxxx/ Good to know, thanks for telling. _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
