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Mark Santaniello authored
Perf script can report the dso for "addr" and "ip" fields. This adds the same support for the "brstack" and "brstacksym" fields. This can be helpful for AutoFDO: we can ignore LBR entries unless the source and target address are both in the target module we are about to build. I built a small test akin to "while(1) { do_nothing(); }" where the do_nothing function is loaded from a dso: $ cat burncpu.cpp #include <dlfcn.h> int main() { void* handle = dlopen("./dso.so", RTLD_LAZY); if (!handle) return -1; typedef void (*fp)(); fp do_nothing = (fp) dlsym(handle, "do_nothing"); while(1) { do_nothing(); } } $ cat dso.cpp extern "C" void do_nothing() {} $ cat build.sh #!/bin/bash g++ -shared dso.cpp -o dso.so g++ burncpu.cpp -o burncpu -ldl I sampled the execution with perf record -b. Using the new perf script functionality I can easily find cases where there was a transition from one dso to another: $ perf record -a -b -- sleep 5 [ perf record: Woken up 55 times to write data ] [ perf record: Captured and wrote 18.815 MB perf.data (43593 samples) ] $ perf script -F brstack,dso | sed 's/\/0 /\/0\n/g' | grep burncpu | grep dso.so | head -n 1 0x7f967139b6aa(/tmp/burncpu/dso.so)/0x4006b1(/tmp/burncpu/exe)/P/-/-/0 $ perf script -F brstacksym,dso | sed 's/\/0 /\/0\n/g' | grep burncpu | grep dso.so | head -n 1 do_nothing+0x5(/tmp/burncpu/dso.so)/main+0x44(/tmp/burncpu/exe)/P/-/-/0 Signed-off-by:
Mark Santaniello <marksan@fb.com> Tested-by:
Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170619163825.2012979-1-marksan@fb.comSigned-off-by:
Arnaldo Carvalho de Melo <acme@redhat.com>
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