On Thu 23-11-17 13:36:29, Mel Gorman wrote: > On Thu, Nov 23, 2017 at 01:25:30PM +0100, Michal Hocko wrote: > > On Thu 23-11-17 11:43:36, peter.enderb...@sony.com wrote: > > > From: Peter Enderborg <peter.enderb...@sony.com> > > > > > > The warning of slow allocation has been removed, this is > > > a other way to fetch that information. But you need > > > to enable the trace. The exit function also returns > > > information about the number of retries, how long > > > it was stalled and failure reason if that happened. > > > > I think this is just too excessive. We already have a tracepoint for the > > allocation exit. All we need is an entry to have a base to compare with. > > Another usecase would be to measure allocation latency. Information you > > are adding can be (partially) covered by existing tracepoints. > > > > You can gather that by simply adding a probe to __alloc_pages_slowpath > (like what perf probe does) and matching the trigger with the existing > mm_page_alloc points.
I am not sure adding a probe on a production system will fly in many cases. A static tracepoint would be much easier in that case. But I agree there are other means to accomplish the same thing. My main point was to have an easy out-of-the-box way to check latencies. But that is not something I would really insist on. -- Michal Hocko SUSE Labs
