Hello, On Thu, Jul 11, 2024 at 02:25:29AM +0000, Boy Wu (吳勃誼) wrote: ... > I can remove the 32bit only define, but I think we need to add back the > u64 sync, because the spin lock and the u64 sync serve different > purposes. The spin lock is for handling concurrent problems from > different CPUs updating stats, and u64 sync is for updating 64 bits > data and fetching 64 bits data from different CPUs in 32bit SMP > systems. Hmm... so what I'm suggesting is using u64_sync for the per-cpu stat structure as they are guaranteed to have only one updater with irq disabled and use a spinlock for the shared iostat which can have multiple updaters and isn't accessed that frequently. Thanks. -- tejun
