Hi, This is an early RFC version adding transparent huge page support for PPC64. I am sharing the changes, so that we can have early review on the approach taken. The TODOs include
*) Compile issues with different config option *) HugeTLBfs is disabled now (mostly compile issues) *) PPC32 and other sub architecture details need to be worked out. *) 4K page size details need to be worked out *) Closer review of PMD* flags. Some numbers: The latency measurements code from Anton found at http://ozlabs.org/~anton/junkcode/latency2001.c THP disabled 64K page size ------------------------ [root@llmp24l02 ~]# ./latency2001 8G 8589934592 731.73 cycles 205.77 ns [root@llmp24l02 ~]# ./latency2001 8G 8589934592 743.39 cycles 209.05 ns [root@llmp24l02 ~]# THP disabled large page via hugetlbfs ------------------------------------- [root@llmp24l02 ~]# ./latency2001 -l 8G 8589934592 416.09 cycles 117.01 ns [root@llmp24l02 ~]# ./latency2001 -l 8G 8589934592 415.74 cycles 116.91 ns THP enabled 64K page size. ---------------- [root@llmp24l02 ~]# ./latency2001 8G 8589934592 405.07 cycles 113.91 ns [root@llmp24l02 ~]# ./latency2001 8G 8589934592 411.82 cycles 115.81 ns [root@llmp24l02 ~]# We are close to hugetlbfs in latency and we can achieve this with zero config/page reservation. Most of the allocations above are fault allocated. I haven't really measured the collapse alloc impact. Another test that does 50000000 random access over 1GB area goes from 2.65 seconds to 1.07 seconds with this patchset. Thanks, -aneesh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
