On Thu, Oct 17, 2024 at 02:18:41PM +0800, lizhe.67@xxxxxxxxxxxxx wrote: > On Wed, 16 Oct 2024 12:53:15 +0100, willy@xxxxxxxxxxxxx wrote: > > >On Wed, Oct 16, 2024 at 12:36:00PM +0800, lizhe.67@xxxxxxxxxxxxx wrote: > >> From: Li Zhe <lizhe.67@xxxxxxxxxxxxx> > >> > >> In function collapse_huge_page(), we drop mmap read lock and get > >> mmap write lock to prevent most accesses to pagetables. There is > >> a small time window to allow other tasks to acquire the mmap lock. > >> With the use of upgrade_read(), we don't need to check vma and pmd > >> again in most cases. > > > >This is clearly a performance optimisation. So you must have some > >numebrs that justify this, please include them. > > Yes, I will add the relevant data to v2 patch. How about telling us all now so we know whether to continue discussing this?
