* Pekka Enberg <penberg@xxxxxxxxxx> wrote: > On Wed, Jan 26, 2011 at 7:22 PM, Robert Jennings> <rcj@xxxxxxxxxxxxxxxxxx> wrote: >> 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 <snip> >> @@ -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 > > This is handled by the else branch already, no? Yes, it does not need to be there. I will repost. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
