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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>
hifive-unleashed-5.1
Witold Baryluk 2009-03-17 21:15:44 +01:00 committed by Steven Rostedt
parent af4617bdba
commit 97e7e4f391
1 changed files with 2 additions and 4 deletions
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6
include/linux/compiler.h
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@ -68,6 +68,7 @@ struct ftrace_branch_data {
unsigned long miss; unsigned long miss;
unsigned long hit; unsigned long hit;
}; };
unsigned long miss_hit[2];
}; };
}; };
@ -125,10 +126,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
.line = __LINE__, \ .line = __LINE__, \
}; \ }; \
______r = !!(cond); \ ______r = !!(cond); \
if (______r) \ ______f.miss_hit[______r]++; \
______f.hit++; \
else \
______f.miss++; \
______r; \ ______r; \
})) }))
#endif /* CONFIG_PROFILE_ALL_BRANCHES */ #endif /* CONFIG_PROFILE_ALL_BRANCHES */