On Tue, Oct 09, 2018 at 02:27:45PM +0200, Michal Hocko wrote: > [Sorry for being slow in responding but I was mostly offline last few > days] > > On Tue 09-10-18 10:48:25, Mel Gorman wrote: > [...] > > This goes back to my point that the MADV_HUGEPAGE hint should not make > > promises about locality and that introducing MADV_LOCAL for specialised > > libraries may be more appropriate with the initial semantic being how it > > treats MADV_HUGEPAGE regions. > > I agree with your other points and not going to repeat them. I am not > sure madvise s the best API for the purpose though. We are talking about > memory policy here and there is an existing api for that so I would > _prefer_ to reuse it for this purpose. > I flip-flopped on that one in my head multiple times on the basis of how strict it should be. Memory policies tend to be black or white -- bind here, interleave there, etc. It wasn't clear to me what the best policy would be to describe "allocate local as best as you can but allow fallbacks if necessary". Hence, I started leaning towards advise as it is really about advice that the kernel can ignore if necessary. That said, I don't feel as strongly about the "how" as I do about the fact that applications and libraries should not depend on side-effects of the MADV_HUGEPAGE implementation that relate to locality. -- Mel Gorman SUSE Labs
