There are several algorithms available for raid6 to generate xor and syndrome parity, including basic int1, int2 ... int32 and SIMD optimized implementation like sse and neon. To test and choose the best algorithms at the initial stage, we need provide enough disk data to feed the algorithms. However, the disk number we provided depends on page size and gfmul table, seeing bellow: const int disks = (65536/PAGE_SIZE) + 2; So when come to 64K PAGE_SIZE, there is only one data disk plus 2 parity disk, as a result the chosed algorithm is not reliable. For example, on my arm64 machine with 64K page enabled, it will choose intx32 as the best one, although the NEON implementation is better. This patch tries to fix the problem by defining a constant raid6 disk number to supporting arbitrary page size.
Showing the changes to include/linux (1 of 2 files). Show all
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| @@ -28,6 +28,7 @@ extern const char raid6_empty_zero_page[PAGE_SIZE]; · 27 unmodified lines | |||
| 28 | #include <errno.h> | 28 | #include <errno.h> |
| 29 | #include <inttypes.h> | 29 | #include <inttypes.h> |
| 30 | #include <stddef.h> | 30 | #include <stddef.h> |
| 31 | #include <string.h> | ||
| 31 | #include <sys/mman.h> | 32 | #include <sys/mman.h> |
| 32 | #include <sys/time.h> | 33 | #include <sys/time.h> |
| 33 | #include <sys/types.h> | 34 | #include <sys/types.h> |
| @@ -43,6 +44,9 @@ typedef uint64_t u64; · 9 unmodified lines | |||
| 43 | #ifndef PAGE_SIZE | 44 | #ifndef PAGE_SIZE |
| 44 | # define PAGE_SIZE 4096 | 45 | # define PAGE_SIZE 4096 |
| 45 | #endif | 46 | #endif |
| 47 | #ifndef PAGE_SHIFT | ||
| 48 | # define PAGE_SHIFT 12 | ||
| 49 | #endif | ||
| 46 | extern const char raid6_empty_zero_page[PAGE_SIZE]; | 50 | extern const char raid6_empty_zero_page[PAGE_SIZE]; |
| 47 | 51 | ||
| 48 | #define __init | 52 | #define __init |