On Mon 15-05-17 16:44:26, Pasha Tatashin wrote: > On 05/15/2017 03:38 PM, Michal Hocko wrote: > >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. > > OK, I will think about this. > > I do not really like adding new configs because they tend to clutter the > code. This is why, Yes I hate adding new (arch) config options as well. And I still believe we do not need any here either... > I wanted to rely on already existing config that I know benefits all > platforms that use it. I wouldn't be so sure about this. If any other platform has a similar issues with small memset as sparc then the overhead is just papered over by parallel initialization. > Eventually, > "CONFIG_DEFERRED_STRUCT_PAGE_INIT" is going to become the default > everywhere, as there should not be a drawback of using it even on small > machines. Maybe and I would highly appreciate that. -- 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
