On Wed, 2016-07-27 at 20:44 +0200, Michal Hocko wrote: > On Wed 27-07-16 14:16:22, Rik van Riel wrote: > > > > On Wed, 2016-07-27 at 18:33 +0200, Michal Hocko wrote: > > > > > > On Wed 27-07-16 10:47:59, Janani Ravichandran wrote: > > > > > > > > > > > > Add tracepoints to the slowpath code to gather some > > > > information. > > > > The tracepoints can also be used to find out how much time was > > > > spent in > > > > the slowpath. > > > I do not think this is a right thing to measure. > > > __alloc_pages_slowpath > > > is more a code organization thing. The fast path might perform an > > > expensive operations like zone reclaim (if node_reclaim_mode > 0) > > > so > > > these trace point would miss it. > > It doesn't look like it does. The fast path either > > returns an allocated page to the caller, or calls > > into the slow path. > I must be missing something here but what prevents > __alloc_pages_nodemask->get_page_from_freelist from doing > zone_reclaim? You are right! Guess the script may need to collect all the tracing output from __alloc_pages_nodemask on up, and then filter the output so only the interesting (read: long duration) traces get dumped out to a file. -- All rights reversed
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