update perf script (#51)

motivation: beter perf script

changes:
* adjust to latest version of perf
* higher frequency sampling
* more debug symbols

Author: tomerd

scripts/linux_performance_setup.sh

@@ -16,13 +16,13 @@
 # docker run --privileged -it -v `pwd`:/code -w /code swiftlang/swift:nightly-5.2-bionic bash
 
 apt-get update -y
-apt-get install -y vim htop strace linux-tools-common linux-tools-generic
+apt-get install -y vim htop strace linux-tools-common linux-tools-generic libc6-dbg
 
 echo 0 > /proc/sys/kernel/kptr_restrict
 
 cd /usr/bin
 rm -rf perf
-ln -s /usr/lib/linux-tools/4.15.0-88-generic/perf perf
+ln -s /usr/lib/linux-tools/4.15.0-91-generic/perf perf
 cd -
 
 cd /opt
@@ -42,5 +42,5 @@ cd -
 #
 # perf
 # export MAX_REQUESTS=10000
-# perf record -o .build/perf-$MAX_REQUESTS.data -g .build/release/StringSample dwarf
+# perf record -o .build/perf-$MAX_REQUESTS.data -g -F 100000 .build/release/StringSample dwarf
 # perf script -i .build/perf-$MAX_REQUESTS.data | /opt/FlameGraph/stackcollapse-perf.pl | swift-demangle | /opt/FlameGraph/flamegraph.pl > .build/flamegraph-$MAX_REQUESTS.svg