On 09/06/2017 03:49 PM, Michal Hocko wrote: > On Thu 31-08-17 09:55:25, Vlastimil Babka wrote: >> On 08/23/2017 08:47 AM, Vlastimil Babka wrote: >>> On 07/24/2017 02:38 PM, Michal Hocko wrote: >>>> On Thu 20-07-17 15:40:26, Vlastimil Babka wrote: >>>>> In init_pages_in_zone() we currently use the generic set_page_owner() function >>>>> to initialize page_owner info for early allocated pages. This means we >>>>> needlessly do lookup_page_ext() twice for each page, and more importantly >>>>> save_stack(), which has to unwind the stack and find the corresponding stack >>>>> depot handle. Because the stack is always the same for the initialization, >>>>> unwind it once in init_pages_in_zone() and reuse the handle. Also avoid the >>>>> repeated lookup_page_ext(). >>>> >>>> Yes this looks like an improvement but I have to admit that I do not >>>> really get why we even do save_stack at all here. Those pages might >>>> got allocated from anywhere so we could very well provide a statically >>>> allocated "fake" stack trace, no? >>> >>> We could, but it's much simpler to do it this way than try to extend >>> stack depot/stack saving to support creating such fakes. Would it be >>> worth the effort? >> >> Ah, I've noticed we already do this for the dummy (prevent recursion) >> stack and failure stack. So here you go. It will also make the fake >> stack more obvious after "[PATCH 2/2] mm, page_owner: Skip unnecessary >> stack_trace entries" is merged, which would otherwise remove >> init_page_owner() from the stack. > > Yes this is what I've had in mind. > >> ----8<---- >> >From 9804a5e62fc768e12b86fd4a3184e692c59ebfd1 Mon Sep 17 00:00:00 2001 >> From: Vlastimil Babka <vbabka@xxxxxxx> >> Date: Thu, 31 Aug 2017 09:46:46 +0200 >> Subject: [PATCH] mm, page_owner: make init_pages_in_zone() faster-fix2 >> >> Create statically allocated fake stack trace for early allocated pages, per >> Michal Hocko. > > Yes this looks good to me. I am just wondering why we need 3 different > fake stacks. I do not see any code that would special case them when > dumping traces. Maybe this can be done on top? It's so that the user can differentiate them in the output. That's why the functions are noinline. >> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> > > Anyway > Acked-by: Michal Hocko <mhocko@xxxxxxxx> Thanks! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
