perf 对某个CPU进行perf，生成火焰图：
# 只 perf 42 核
perf record -p `pidof retrievalx_server` -g -c 42
perf script -i perf.data | FlameGraph-master/stackcollapse-perf.pl > out.perf-folded
cat out.perf-folded | FlameGraph-master/flamegraph.pl > perf.svgperf 对某个CPU进行perf，生成火焰图：
# 只 perf 42 核
perf record -p `pidof retrievalx_server` -g -c 42
perf script -i perf.data | FlameGraph-master/stackcollapse-perf.pl > out.perf-folded
cat out.perf-folded | FlameGraph-master/flamegraph.pl > perf.svg