On Sat, Apr 29, 2023 at 04:27:58PM +0800, Yin Fengwei wrote: > free_transhuge_page() acquires split queue lock then check > whether the THP was added to deferred list or not. It brings > high deferred queue lock contention. > > It's safe to check whether the THP is in deferred list or not > without holding the deferred queue lock in free_transhuge_page() > because when code hit free_transhuge_page(), there is no one > tries to add the folio to _deferred_list. > > Running page_fault1 of will-it-scale + order 2 folio for anonymous > mapping with 96 processes on an Ice Lake 48C/96T test box, we could > see the 61% split_queue_lock contention: > - 63.02% 0.01% page_fault1_pro [kernel.kallsyms] [k] free_transhuge_page > - 63.01% free_transhuge_page > + 62.91% _raw_spin_lock_irqsave > > With this patch applied, the split_queue_lock contention is less > than 1%. > > Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> -- Kiryl Shutsemau / Kirill A. Shutemov
