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authorKen Steele <ken@tilera.com>2013-08-07 12:39:56 -0400
committerNeilBrown <neilb@suse.de>2013-08-27 16:05:50 +1000
commitae77cbc1e7b90473a2b0963bce0e1eb163873214 (patch)
tree0d412c9c4932c59c8b495aa6214f98404849af60 /lib/raid6/tilegx.uc
parent275c51c4e34ed776d40a99dd97c1deee50303b07 (diff)
RAID: add tilegx SIMD implementation of raid6
This change adds TILE-Gx SIMD instructions to the software raid (md), modeling the Altivec implementation. This is only for Syndrome generation; there is more that could be done to improve recovery, as in the recent Intel SSE3 recovery implementation. The code unrolls 8 times; this turns out to be the best on tilegx hardware among the set 1, 2, 4, 8 or 16. The code reads one cache-line of data from each disk, stores P and Q then goes to the next cache-line. The test code in sys/linux/lib/raid6/test reports 2008 MB/s data read rate for syndrome generation using 18 disks (16 data and 2 parity). It was 1512 MB/s before this SIMD optimizations. This is running on 1 core with all the data in cache. This is based on the paper The Mathematics of RAID-6. (http://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf). Signed-off-by: Ken Steele <ken@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'lib/raid6/tilegx.uc')
-rw-r--r--lib/raid6/tilegx.uc86
1 files changed, 86 insertions, 0 deletions
diff --git a/lib/raid6/tilegx.uc b/lib/raid6/tilegx.uc
new file mode 100644
index 000000000000..e7c29459cbcd
--- /dev/null
+++ b/lib/raid6/tilegx.uc
@@ -0,0 +1,86 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ * Copyright 2002 H. Peter Anvin - All Rights Reserved
+ * Copyright 2012 Tilera Corporation - All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
+ * Boston MA 02111-1307, USA; either version 2 of the License, or
+ * (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * tilegx$#.c
+ *
+ * $#-way unrolled TILE-Gx SIMD for RAID-6 math.
+ *
+ * This file is postprocessed using unroll.awk.
+ *
+ */
+
+#include <linux/raid/pq.h>
+
+/* Create 8 byte copies of constant byte */
+# define NBYTES(x) (__insn_v1addi(0, x))
+# define NSIZE 8
+
+/*
+ * The SHLBYTE() operation shifts each byte left by 1, *not*
+ * rolling over into the next byte
+ */
+static inline __attribute_const__ u64 SHLBYTE(u64 v)
+{
+ /* Vector One Byte Shift Left Immediate. */
+ return __insn_v1shli(v, 1);
+}
+
+/*
+ * The MASK() operation returns 0xFF in any byte for which the high
+ * bit is 1, 0x00 for any byte for which the high bit is 0.
+ */
+static inline __attribute_const__ u64 MASK(u64 v)
+{
+ /* Vector One Byte Shift Right Signed Immediate. */
+ return __insn_v1shrsi(v, 7);
+}
+
+
+void raid6_tilegx$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
+{
+ u8 **dptr = (u8 **)ptrs;
+ u64 *p, *q;
+ int d, z, z0;
+
+ u64 wd$$, wq$$, wp$$, w1$$, w2$$;
+ u64 x1d = NBYTES(0x1d);
+ u64 * z0ptr;
+
+ z0 = disks - 3; /* Highest data disk */
+ p = (u64 *)dptr[z0+1]; /* XOR parity */
+ q = (u64 *)dptr[z0+2]; /* RS syndrome */
+
+ z0ptr = (u64 *)&dptr[z0][0];
+ for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
+ wq$$ = wp$$ = *z0ptr++;
+ for ( z = z0-1 ; z >= 0 ; z-- ) {
+ wd$$ = *(u64 *)&dptr[z][d+$$*NSIZE];
+ wp$$ = wp$$ ^ wd$$;
+ w2$$ = MASK(wq$$);
+ w1$$ = SHLBYTE(wq$$);
+ w2$$ = w2$$ & x1d;
+ w1$$ = w1$$ ^ w2$$;
+ wq$$ = w1$$ ^ wd$$;
+ }
+ *p++ = wp$$;
+ *q++ = wq$$;
+ }
+}
+
+const struct raid6_calls raid6_tilegx$# = {
+ raid6_tilegx$#_gen_syndrome,
+ NULL,
+ "tilegx$#",
+ 0
+};