Messages in this thread | | | Date | Mon, 6 Nov 2017 19:18:35 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH] mm, sparse: do not swamp log with huge vmemmap allocation failures |
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On Mon 06-11-17 11:14:27, Khalid Aziz wrote: > On Mon, 2017-11-06 at 10:22 +0100, Michal Hocko wrote: > > From: Michal Hocko <mhocko@suse.com> > > > > While doing a memory hotplug tests under a heavy memory pressure we > > have > > noticed too many page allocation failures when allocating vmemmap > > memmap > > backed by huge page > > ......... deleted ......... > > + > > + if (!warned) { > > + warn_alloc(gfp_mask, NULL, "vmemmap alloc > > failure: order:%u", order); > > + warned = true; > > + } > > return NULL; > > } else > > return __earlyonly_bootmem_alloc(node, size, size, > > This will warn once and only once after a kernel is booted. This > condition may happen repeatedly over a long period of time with > significant time span between two such events and it can be useful to > know if this is happening repeatedly. There might be better ways to > throttle the rate of warnings, something like warn once and then > suppress warnings for the next 15 minutes (or pick any other time > frame). If this condition happens again later, there will be another > warning.
While this is all true I am not sure we care all that much. The failure mode is basically not using an optimization. This is not something we warn normally about. Even the performance degradation is a theoretical concern which nobody has backed by real life numbers AFAIR.
If we want to make it more sophisticated I would expect some numbers to back such a change. -- Michal Hocko SUSE Labs
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