diff --git a/dist/core.c b/dist/core.c
index fcd1876..3d15316 100644
--- a/dist/core.c
+++ b/dist/core.c
@@ -61296,6 +61296,8 @@ void callgrind_start_instrumentation() {}
 
 void callgrind_stop_instrumentation() {}
 
+void callgrind_toggle_collect() {}
+
 void callgrind_add_obj_skip(uint8_t const *path) { (void)path; }
 #else
 #include "callgrind.h"
@@ -61315,6 +61317,8 @@ void callgrind_start_instrumentation() { CALLGRIND_START_INSTRUMENTATION; }
 
 void callgrind_stop_instrumentation() { CALLGRIND_STOP_INSTRUMENTATION; }
 
+void callgrind_toggle_collect() { CALLGRIND_TOGGLE_COLLECT; }
+
 void callgrind_add_obj_skip(uint8_t const *path) {
   CALLGRIND_ADD_OBJ_SKIP(path);
 }
diff --git a/includes/core.h b/includes/core.h
index de4e65d..0690d91 100644
--- a/includes/core.h
+++ b/includes/core.h
@@ -49,6 +49,13 @@ uint64_t instrument_hooks_current_timestamp(void);
 void callgrind_start_instrumentation();
 void callgrind_stop_instrumentation();
 
+// Toggle callgrind cost collection on/off without re-instrumenting.
+// Unlike start/stop instrumentation, this does not flush the simulated
+// cache, so it can be used to exclude code regions from measurement
+// without introducing artificial cold-cache costs.
+// Safe to call outside Valgrind: expands to a no-op.
+void callgrind_toggle_collect();
+
 // Register an object file path on callgrind's runtime --obj-skip list.
 // Equivalent to passing --obj-skip=<path> on the valgrind command line.
 // Safe to call outside Valgrind: expands to a no-op.
diff --git a/src/helpers/valgrind_wrapper.c b/src/helpers/valgrind_wrapper.c
index 00ed042..c338c04 100644
--- a/src/helpers/valgrind_wrapper.c
+++ b/src/helpers/valgrind_wrapper.c
@@ -17,6 +17,8 @@ void callgrind_start_instrumentation() {}
 
 void callgrind_stop_instrumentation() {}
 
+void callgrind_toggle_collect() {}
+
 void callgrind_add_obj_skip(uint8_t const *path) { (void)path; }
 #else
 #include "callgrind.h"
@@ -36,6 +38,8 @@ void callgrind_start_instrumentation() { CALLGRIND_START_INSTRUMENTATION; }
 
 void callgrind_stop_instrumentation() { CALLGRIND_STOP_INSTRUMENTATION; }
 
+void callgrind_toggle_collect() { CALLGRIND_TOGGLE_COLLECT; }
+
 void callgrind_add_obj_skip(uint8_t const *path) {
   CALLGRIND_ADD_OBJ_SKIP(path);
 }