On Thu, 1 Sep 2016 08:16:54 -0700 "Huang, Ying" <[email protected]> wrote:
> From: Huang Ying <[email protected]> > > In this patch, the size of the swap cluster is changed to that of the > THP (Transparent Huge Page) on x86_64 architecture (512). This is for > the THP swap support on x86_64. Where one swap cluster will be used to > hold the contents of each THP swapped out. And some information of the > swapped out THP (such as compound map count) will be recorded in the > swap_cluster_info data structure. > > In effect, this will enlarge swap cluster size by 2 times. Which may > make it harder to find a free cluster when the swap space becomes > fragmented. So that, this may reduce the continuous swap space > allocation and sequential write in theory. The performance test in 0day > show no regressions caused by this. > > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -196,7 +196,7 @@ static void discard_swap_cluster(struct swap_info_struct > *si, > } > } > > -#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?
