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target: Correct profiling calculation

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1. high_pc should be (maximum sample + 1) (Refer to gprof source code)
2. bucket index should be

     sample offset
    --------------- x (number of bucket)
	 sample range

For example, if minimum sample is 0 and maximum sample is 5
and the number of bucket is 3.

a = sampled_address - 0
b = 3
c = 6
(a, b, c refer to source code variables)

sampled_address = 0, => a = 0, => bucket_index = 0
sampled_address = 1, => a = 1, => bucket_index = 0
sampled_address = 2, => a = 2, => bucket_index = 1
sampled_address = 3, => a = 3, => bucket_index = 1
sampled_address = 4, => a = 4, => bucket_index = 2
sampled_address = 5, => a = 5, => bucket_index = 2

Change-Id: Ia9fa0e4d9c7183e3e9d7ceaf73e63729f07aa2ce
Signed-off-by: Hsiangkai Wang <hsiangkai@gmail.com>
Reviewed-on: http://openocd.zylin.com/1607
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>
This commit is contained in:
Hsiangkai Wang 2013-08-30 13:35:08 +08:00 committed by Spencer Oliver
parent a4bacdcb84
commit d4d62ea8a8
1 changed files with 7 additions and 3 deletions
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10
src/target/target.c
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@ -3387,7 +3387,11 @@ static void writeGmon(uint32_t *samples, uint32_t sampleNum, const char *filenam
max = samples[i];
}
int addressSpace = (max - min + 1);
/* max should be (largest sample + 1)
* Refer to binutils/gprof/hist.c (find_histogram_for_pc) */
max++;
int addressSpace = max - min;
assert(addressSpace >= 2);
static const uint32_t maxBuckets = 16 * 1024; /* maximum buckets. */
@ -3403,8 +3407,8 @@ static void writeGmon(uint32_t *samples, uint32_t sampleNum, const char *filenam
for (i = 0; i < sampleNum; i++) {
uint32_t address = samples[i];
long long a = address - min;
long long b = numBuckets - 1;
long long c = addressSpace - 1;
long long b = numBuckets;
long long c = addressSpace;
int index_t = (a * b) / c; /* danger!!!! int32 overflows */
buckets[index_t]++;
}