Messages in this thread | | | Date | Mon, 23 Apr 2018 17:41:06 -0500 (CDT) | From | Christopher Lameter <> | Subject | Re: [PATCH] SLUB: Do not fallback to mininum order if __GFP_NORETRY is set |
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On Sat, 21 Apr 2018, Vlastimil Babka wrote:
> > The problem is that SLUB does not honor GFP_NORETRY. The semantics of > > GFP_NORETRY are not followed. > > The caller might want SLUB to try hard to get that high-order page that > will minimize memory waste (e.g. 2MB page for 3 640k objects), and > __GFP_NORETRY will kill the effort on allocating that high-order page.
Well yes since *_NORETRY says that fallbacks are acceptable.
> Thus, using __GPF_NORETRY for "please give me a space-optimized object, > or nothing (because I have a fallback that's better than wasting memory, > e.g. by using 1MB page for 640kb object)" is not ideal. > > Maybe __GFP_RETRY_MAYFAIL is a better fit? Or perhaps indicate this > situation to SLUB with e.g. __GFP_COMP, although that's rather ugly?
Yuck. None of that sounds like an intuitive approach.
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