On Mon 15-05-17 14:12:10, Pasha Tatashin wrote: > Hi Michal, > > After looking at your suggested memblock_virt_alloc_core() change again, I > decided to keep what I have. I do not want to inline > memblock_virt_alloc_internal(), because it is not a performance critical > path, and by inlining it we will unnecessarily increase the text size on all > platforms. I do not insist but I would really _prefer_ if the bool zero argument didn't proliferate all over the memblock API. > Also, because it will be very hard to make sure that no platform regresses > by making memset() default in _memblock_virt_alloc_core() (as I already > showed last week at least sun4v SPARC64 will require special changes in > order for this to work), I decided to make it available only for "deferred > struct page init" case. As, what is already in the patch. I do not think this is the right approach. Your measurements just show that sparc could have a more optimized memset for small sizes. If you keep the same memset only for the parallel initialization then you just hide this fact. I wouldn't worry about other architectures. All sane architectures should simply work reasonably well when touching a single or only few cache lines at the same time. If some arches really suffer from small memsets then the initialization should be driven by a specific ARCH_WANT_LARGE_PAGEBLOCK_INIT rather than making this depend on DEFERRED_INIT. Or if you are too worried then make it opt-in and make it depend on ARCH_WANT_PER_PAGE_INIT and make it enabled for x86 and sparc after memset optimization. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
