Linux + x86_64 optimisations.

Add likely() macro.
Optimise a few obvious code paths with likely/unlikely.
Change algo to sse2_amd64 by default.
Move priority change to worker threads only.
Detect number of CPUs and set default number of threads == CPUs.
Add scheduling policy change to worker threads to SCHED_IDLE first and fallback to SCHED_BATCH on linux.
Don't error when failing to set priority.
Add CPU affinity and bind worker threads to CPUs when number of threads is a multiple of number of CPUs.
Update NEWS with changes.

1 files changed, 5 insertions, 3 deletions

diff --git a/miner.h b/miner.h
index 0781ce7..e72404f 100644
--- a/miner.h
+++ b/miner.h
@@ -87,12 +87,14 @@ enum {
 };
 #endif
 
-#if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
 #undef unlikely
-#define unlikely(expr) (__builtin_expect((expr), 0))
+#undef likely
+#if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
+#define unlikely(expr) (__builtin_expect(!!(expr), 0))
+#define likely(expr) (__builtin_expect(!!(expr), 1))
 #else
-#undef unlikely
 #define unlikely(expr) (expr)
+#define likely(expr) (expr)
 #endif
 
 #if defined(__i386__)