Update flush_cache for Linux

Author: BenBrock

examples/benchmark_read.c

@@ -43,6 +43,8 @@ double compute_variance(double* x, size_t n) {
 void flush_cache() {
 #ifdef __APPLE__
   system("bash -c \"sync && sudo purge\"");
+#elif __LINUX__
+  system("bash -c \"sync\" && sudo echo 3 > /proc/sys/vm/drop_caches");
 #else
   static_assert(false);
 #endif

examples/benchmark_write.c

@@ -43,6 +43,8 @@ double compute_variance(double* x, size_t n) {
 void flush_cache() {
 #ifdef __APPLE__
   system("bash -c \"sync && sudo purge\"");
+#elif __LINUX__
+  system("bash -c \"sync\" && sudo echo 3 > /proc/sys/vm/drop_caches");
 #else
   static_assert(false);
 #endif
@@ -51,6 +53,8 @@ void flush_cache() {
 void flush_writes() {
 #ifdef __APPLE__
   system("bash -c \"sync\"");
+#elif __LINUX__
+  system("bash -c \"sync\"");
 #else
   static_assert(false);
 #endif