tracing: optimization of branch tracer
Impact: better performance for if branch tracer
Use an array to count the hit and misses of a conditional instead
of using another conditional. This cuts down on saturation of branch
predictions and increases performance of modern pipelined architectures.
Signed-off-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index d95da10..6faa7e5 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -68,6 +68,7 @@
unsigned long miss;
unsigned long hit;
};
+ unsigned long miss_hit[2];
};
};
@@ -125,10 +126,7 @@
.line = __LINE__, \
}; \
______r = !!(cond); \
- if (______r) \
- ______f.hit++; \
- else \
- ______f.miss++; \
+ ______f.miss_hit[______r]++; \
______r; \
}))
#endif /* CONFIG_PROFILE_ALL_BRANCHES */