Hi Andrew, On 5/4/23 19:48, kirill@xxxxxxxxxxxxx wrote: > 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> I didn't get the green light for patch2 (which was trying to reduce lru lock contention) from Matthew. It may need more time to figure out how to reduce lru lock contention. I am wondering whether this patch1 (without patch2) can be picked as - It has nothing to do with patch2 - It could reduce the deferred queue lock contention. - It got acked-by from Kirill. Let me know if you want me to resend this patch1. Thanks. Regards Yin, Fengwei >
