[PATCH] Use strict priority ranking for pq gen() benchmarking

["Dirk Müller" <dmueller@suse.de>]

On x86_64, currently 3 variants of AVX512, 3 variants of AVX2
and 3 variants of SSE2 are benchmarked on initialization, taking
between 144-153 jiffies. Over a hardware pool of various generations
of intel cpus I could not find a single case where SSE2 won over
AVX2 or AVX512. There are cases where AVX2 wins over AVX512.

By giving AVXx variants higher priority over SSE, we can generally
skip 3 benchmarks which speeds this up by 33% - 50%, depending on
whether AVX512 is available.

Signed-off-by: Dirk Müller <dmueller@suse.de>
---
 include/linux/raid/pq.h | 2 +-
 lib/raid6/algos.c       | 2 +-
 lib/raid6/avx2.c        | 6 +++---
 lib/raid6/avx512.c      | 6 +++---
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/linux/raid/pq.h b/include/linux/raid/pq.h
index 154e954b711d..d6e5a1feb947 100644
--- a/include/linux/raid/pq.h
+++ b/include/linux/raid/pq.h
@@ -81,7 +81,7 @@ struct raid6_calls {
 	void (*xor_syndrome)(int, int, int, size_t, void **);
 	int  (*valid)(void);	/* Returns 1 if this routine set is usable */
 	const char *name;	/* Name of this routine set */
-	int prefer;		/* Has special performance attribute */
+	int priority;		/* Relative priority ranking if non-zero */
 };
 
 /* Selected algorithm */
diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c
index 889033b7fc0d..d1e8ff837a32 100644
--- a/lib/raid6/algos.c
+++ b/lib/raid6/algos.c
@@ -151,7 +151,7 @@ static inline const struct raid6_calls *raid6_choose_gen(
 	const struct raid6_calls *best;
 
 	for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
-		if (!best || (*algo)->prefer >= best->prefer) {
+		if (!best || (*algo)->priority >= best->priority) {
 			if ((*algo)->valid && !(*algo)->valid())
 				continue;
 
diff --git a/lib/raid6/avx2.c b/lib/raid6/avx2.c
index f299476e1d76..31be496b8c81 100644
--- a/lib/raid6/avx2.c
+++ b/lib/raid6/avx2.c
@@ -132,7 +132,7 @@ const struct raid6_calls raid6_avx2x1 = {
 	raid6_avx21_xor_syndrome,
 	raid6_have_avx2,
 	"avx2x1",
-	1			/* Has cache hints */
+	.priority = 2
 };
 
 /*
@@ -262,7 +262,7 @@ const struct raid6_calls raid6_avx2x2 = {
 	raid6_avx22_xor_syndrome,
 	raid6_have_avx2,
 	"avx2x2",
-	1			/* Has cache hints */
+	.priority = 2
 };
 
 #ifdef CONFIG_X86_64
@@ -465,6 +465,6 @@ const struct raid6_calls raid6_avx2x4 = {
 	raid6_avx24_xor_syndrome,
 	raid6_have_avx2,
 	"avx2x4",
-	1			/* Has cache hints */
+	.priority = 2
 };
 #endif
diff --git a/lib/raid6/avx512.c b/lib/raid6/avx512.c
index bb684d144ee2..63ae197c3294 100644
--- a/lib/raid6/avx512.c
+++ b/lib/raid6/avx512.c
@@ -162,7 +162,7 @@ const struct raid6_calls raid6_avx512x1 = {
 	raid6_avx5121_xor_syndrome,
 	raid6_have_avx512,
 	"avx512x1",
-	1                       /* Has cache hints */
+	.priority = 2
 };
 
 /*
@@ -319,7 +319,7 @@ const struct raid6_calls raid6_avx512x2 = {
 	raid6_avx5122_xor_syndrome,
 	raid6_have_avx512,
 	"avx512x2",
-	1                       /* Has cache hints */
+	.priority = 2
 };
 
 #ifdef CONFIG_X86_64
@@ -557,7 +557,7 @@ const struct raid6_calls raid6_avx512x4 = {
 	raid6_avx5124_xor_syndrome,
 	raid6_have_avx512,
 	"avx512x4",
-	1                       /* Has cache hints */
+	.priority = 2
 };
 #endif
 
-- 
2.34.1