"Kirill A. Shutemov" <kir...@shutemov.name> writes: > On Tue, Mar 28, 2017 at 01:32:01PM +0800, Huang, Ying wrote: >> From: Huang Ying <ying.hu...@intel.com> >> >> 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. >> >> For other architectures which want THP swap support, >> ARCH_USES_THP_SWAP_CLUSTER need to be selected in the Kconfig file for >> the architecture. > > Intreseting case could be architecture with HPAGE_PMD_NR < 256. > Can current code pack more than one THP per claster.
No. Only one THP for each swap cluster is supported. But in current implementation, if HPAGE_PMD_NR < 256, the swap cluster will be < 256 too. The size of swap cluster will be exact same as HPAGE_PMD_NR. Best Regards, Huang, Ying > If not we need to have BUILG_BUG_ON() to catch attempt of such enabling.
