We have developed the coverage test tool and execution path analyzer using BTS
called "Btrax". It can show the executed/unexecuted source codes with color.
Please refer this slide about details of Btrax.
http://lca2009.linux.org.au/slides/52.pdf
The purpose of 'perf bts' is to implement similar functions to Btrax.
And also, I'll try to reduce memory copies from kernel space to user,
because perf copies 3 times. But btrax does just one copy.
Please see the following benchmark results.
Test program: compile with -O0 option this source code
int main(void)
{
int i;
while(i++ < 100000000);
return 0;
}
Execution Results:
Native:
# time ./a.out
real 0m0.349s
user 0m0.346s
sys 0m0.002s
Btrax:
(enabling BTS_OFF_OS flag for this benchmark)
(kernel 2.6.30 on RHEL 5.4)
# bt_collect_log -d log -c ./a.out
real 1m19.950s
user 0m14.783s
sys 0m40.655s
(trace data size: 1,537,307,064 bytes)
perf:
# time perf bts record ./a.out
Processed 0 events and LOST 5002!
Check IO/CPU overload!
# perf record: Captured and wrote 2704.231 MB perf.data (~118149662 samples)
real 2m1.885s
user 0m7.184s
sys 0m19.194s
Bench Mark Enviroment:
Native and perf: latest -tip kernel on Fedora14
Btrax: vanilla 2.6.30 on RHEL5.4
Core2Duo E6550 @2.33GHz
Mem DDR2 4GB
best regards,
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