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charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 7A667C0010 X-Stat-Signature: x365t7be67ob9e5zemb3goinutouf1gu X-HE-Tag: 1673460570-876002 X-HE-Meta: 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 ce/xfe5G Ul6ViPY2DTrP4OPi1gzKQml+nMODi9C7QRJNuU/fEigZQuZ8WlRIn1JiKsT+/dzfwGGPqg1h99NR3zDiwQhC1K0CrScEbM4VuJ9Q8ye1wmlMtn8M= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jan 11, 2023 at 10:03 AM Michal Hocko wrote: > > On Wed 11-01-23 09:49:08, Suren Baghdasaryan wrote: > > On Wed, Jan 11, 2023 at 9:37 AM Michal Hocko wrote: > > > > > > On Wed 11-01-23 09:04:41, Suren Baghdasaryan wrote: > > > > On Wed, Jan 11, 2023 at 8:44 AM Michal Hocko 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. Good question. I don't have the ready answer to that but will try to collect some stats. I know that many names are standardized but haven't looked at how they are distributed in the address space. Will followup once I collect the data. Thanks, Suren. > -- > Michal Hocko > SUSE Labs