xvmalloc will not currently function with 64K pages. Newly allocated pages will be inserted at an offset beyond the end of the first-level index. This tuning is needed to properly size the allocator for 64K pages. The default 3 byte shift results in a second level list size which can not be indexed using the 64 bits of the flbitmap in the xv_pool structure. The shift must increase to 4 bytes between second level list entries to fit the size of the first level bitmap. Here are a few statistics for structure sizes on 32- and 64-bit CPUs with 4KB and 64KB page sizes. bits_per_long 32 64 64 page_size 4,096 4,096 65,535 xv_align 4 8 8 fl_delta 3 3 4 num_free_lists 508 508 4,094 xv_pool size 4,144b 8,216b 66,040b per object overhead 32 64 64 zram struct 0.5GB disk 512KB 1024KB 64KB This patch maintains the current tunings for 4K pages, adds an optimal sizing for 64K pages and adds a safe tuning for any other page sizes. Signed-off-by: Robert Jennings <rcj@xxxxxxxxxxxxxxxxxx> --- drivers/staging/zram/xvmalloc_int.h | 18 ++++++++++++++++-- 1 files changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/staging/zram/xvmalloc_int.h b/drivers/staging/zram/xvmalloc_int.h index e23ed5c..051a49b 100644 --- a/drivers/staging/zram/xvmalloc_int.h +++ b/drivers/staging/zram/xvmalloc_int.h @@ -19,7 +19,11 @@ /* User configurable params */ /* Must be power of two */ +#ifdef CONFIG_64BIT +#define XV_ALIGN_SHIFT 3 +#else #define XV_ALIGN_SHIFT 2 +#endif #define XV_ALIGN (1 << XV_ALIGN_SHIFT) #define XV_ALIGN_MASK (XV_ALIGN - 1) @@ -27,8 +31,18 @@ #define XV_MIN_ALLOC_SIZE 32 #define XV_MAX_ALLOC_SIZE (PAGE_SIZE - XV_ALIGN) -/* Free lists are separated by FL_DELTA bytes */ -#define FL_DELTA_SHIFT 3 +/* + * Free lists are separated by FL_DELTA bytes + * This value is 3 for 4k pages and 4 for 64k pages, for any + * other page size, a conservative (PAGE_SHIFT - 9) is used. + */ +#if PAGE_SHIFT == 12 +#define FL_DELTA_SHIFT 3 +#elif PAGE_SHIFT == 16 +#define FL_DELTA_SHIFT 4 +#else +#define FL_DELTA_SHIFT (PAGE_SHIFT - 9) +#endif #define FL_DELTA (1 << FL_DELTA_SHIFT) #define FL_DELTA_MASK (FL_DELTA - 1) #define NUM_FREE_LISTS ((XV_MAX_ALLOC_SIZE - XV_MIN_ALLOC_SIZE) \ -- 1.6.0.2 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
