On Thu, 01 Sep 2016 16:04:57 -0700 "Huang\, Ying" <ying.hu...@intel.com> wrote:
> >> } > >> > >> -#define SWAPFILE_CLUSTER 256 > >> +#define SWAPFILE_CLUSTER 512 > >> #define LATENCY_LIMIT 256 > >> > > > > What happens to architectures which have different HPAGE_SIZE and/or > > PAGE_SIZE? > > For the architecture with HPAGE_SIZE / PAGE_SIZE == 512 (for example > x86_64), the huge page swap optimizing will be turned on. For other > architectures, it will be turned off as before. > > This mostly because I don't know whether it is a good idea to turn on > THP swap optimizing for the architectures other than x86_64. For > example, it appears that the huge page size is 8M (1<<23) on SPARC. But > I don't know whether 8M is too big for a swap cluster. And it appears > that the huge page size could be as large as 512M on MIPS. This doesn't sounds very organized. If some architecture with some config happens to have HPAGE_SIZE / PAGE_SIZE == 512 then the feature will be turned on; otherwise it will be turned off. Nobody will even notice that it happened. Would it not be better to do #ifdef CONFIG_SOMETHING #define SWAPFILE_CLUSTER (HPAGE_SIZE / PAGE_SIZE) #else #define SWAPFILE_CLUSTER 256 #endif and, by using CONFIG_SOMETHING in the other appropriate places, enable the feature in the usual fashion?
