On Thu, Dec 18, 2025 at 12:35:18PM -0500, Mathieu Desnoyers wrote: [...] > > Could you utilize this[1] to see a > > comparison of the reader-side performance against RCU/SRCU? > > Good point ! Let's see. > > On a AMD 2x EPYC 9654 96-Core Processor with 192 cores, > hyperthreading disabled, > CONFIG_PREEMPT=y, > CONFIG_PREEMPT_RCU=y, > CONFIG_PREEMPT_HAZPTR=y. > > scale_type ns > ----------------------- > hazptr-smp-mb 13.1 <- this implementation > hazptr-barrier 11.5 <- replace smp_mb() on acquire with > barrier(), requires IPIs on synchronize. > hazptr-smp-mb-hlist 12.7 <- replace per-task hp context and per-cpu > overflow lists by hlist. > rcu 17.0
Hmm.. now looking back, how is it possible that hazptr is faster than RCU on the reader-side? Because a grace period was happening and triggered rcu_read_unlock_special()? This is actualy more interesting. Regards, Boqun > srcu 20.0 > srcu-fast 1.5 > rcu-tasks 0.0 > rcu-trace 1.7 > refcnt 1148.0 > rwlock 1190.0 > rwsem 4199.3 > lock 41070.6 > lock-irq 46176.3 > acqrel 1.1 > > So only srcu-fast, rcu-tasks, rcu-trace and a plain acqrel > appear to beat hazptr read-side performance. > > [...] > [...]
