Hi, On 2023-11-30 21:18:15 -0600, Nathan Bossart wrote: > On Wed, Nov 29, 2023 at 03:29:05PM -0600, Nathan Bossart wrote: > > I haven't done any sort of performance testing on this yet. Some > > preliminary web searches suggest that there is unlikely to be much > > difference between cmpxchg and xchg, but presumably there's some difference > > between xchg and doing cmpxchg in a while loop (as is done in > > atomics/generic.h today). I'll report back once I've had a chance to do > > some testing... > > Some rudimentary tests show a >40% speedup with this patch on x86_64.
On bigger machines, with contention, the wins are likely much higher. I see two orders of magnitude higher throughput in a test program that I had around, on a two socket cascade lake machine. Of course it's also much less powerfull... Greetings, Andres Freund
