On Wed 11-01-23 09:49:08, Suren Baghdasaryan wrote: > On Wed, Jan 11, 2023 at 9:37 AM Michal Hocko <mhocko@xxxxxxxx> wrote: > > > > On Wed 11-01-23 09:04:41, Suren Baghdasaryan wrote: > > > On Wed, Jan 11, 2023 at 8:44 AM Michal Hocko <mhocko@xxxxxxxx> wrote: > > > > > > > > On Wed 11-01-23 08:28:49, Suren Baghdasaryan wrote: > > > > [...] > > > > > Anyhow. Sounds like the overhead of the current design is small enough > > > > > to remove CONFIG_PER_VMA_LOCK and let it depend only on architecture > > > > > support? > > > > > > > > Yes. Further optimizations can be done on top. Let's not over optimize > > > > at this stage. > > > > > > Sure, I won't optimize any further. > > > Just to expand on your question. Original design would be problematic > > > for embedded systems like Android. It notoriously has a high number of > > > VMAs due to anonymous VMAs being named, which prevents them from > > > merging. > > > > What is the usual number of VMAs in that environment? > > I've seen some games which had over 4000 VMAs but that's on the upper > side. In my calculations I used 40000 VMAs as a ballpark number and > rough calculations before size optimization would increase memory > consumption by ~2M (depending on the lock placement in vm_area_struct > it would vary a bit). In Android, the performance team flags any > change that exceeds 500KB, so it would raise questions. Thanks, that is a useful information! This is just slightly off-topic but I ak wondering how much memory those vma names consume. Are there that many unique names or they just happen to be alternating so that neighboring ones tend to be different. -- Michal Hocko SUSE Labs
