From 2d5e79de90d7e5daaec2f77b4e2d0b64c1e523eb Mon Sep 17 00:00:00 2001
From: jovsteva <jovan.j.stevanovic@oracle.com>
Date: Wed, 5 Jun 2024 14:07:40 +0200
Subject: [PATCH] JFR CPU profiler should respect the sampling period.

---
 ....java => PosixSubstrateGlobalSigprofHandler.java} | 10 ++++------
 .../svm/core/posix/PosixSubstrateSigprofHandler.java | 12 ++++++++----
 2 files changed, 12 insertions(+), 10 deletions(-)
 rename substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/{darwin/DarwinSubstrateSigprofHandler.java => PosixSubstrateGlobalSigprofHandler.java} (89%)

diff --git a/substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/darwin/DarwinSubstrateSigprofHandler.java b/substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/PosixSubstrateGlobalSigprofHandler.java
similarity index 89%
rename from substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/darwin/DarwinSubstrateSigprofHandler.java
rename to substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/PosixSubstrateGlobalSigprofHandler.java
index 2398a7c78367..e39a05d005a6 100644
--- a/substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/darwin/DarwinSubstrateSigprofHandler.java
+++ b/substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/PosixSubstrateGlobalSigprofHandler.java
@@ -23,7 +23,7 @@
  * questions.
  */
 
-package com.oracle.svm.core.posix.darwin;
+package com.oracle.svm.core.posix;
 
 import static com.oracle.svm.core.Uninterruptible.CALLED_FROM_UNINTERRUPTIBLE_CODE;
 
@@ -34,18 +34,16 @@
 
 import com.oracle.svm.core.Uninterruptible;
 import com.oracle.svm.core.graal.stackvalue.UnsafeStackValue;
-import com.oracle.svm.core.posix.PosixSubstrateSigprofHandler;
-import com.oracle.svm.core.posix.PosixUtils;
 import com.oracle.svm.core.posix.headers.Time;
 import com.oracle.svm.core.util.TimeUtils;
 
 /**
- * Darwin supports only global timer from POSIX (see {@link PosixSubstrateSigprofHandler}).
+ * Support for POSIX global timer (see {@link PosixSubstrateSigprofHandler}).
  */
-public final class DarwinSubstrateSigprofHandler extends PosixSubstrateSigprofHandler {
+public final class PosixSubstrateGlobalSigprofHandler extends PosixSubstrateSigprofHandler {
 
     @Platforms(Platform.HOSTED_ONLY.class)
-    public DarwinSubstrateSigprofHandler() {
+    public PosixSubstrateGlobalSigprofHandler() {
     }
 
     @Override
diff --git a/substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/PosixSubstrateSigprofHandler.java b/substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/PosixSubstrateSigprofHandler.java
index 3a90c84f5369..03c90de21811 100644
--- a/substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/PosixSubstrateSigprofHandler.java
+++ b/substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/PosixSubstrateSigprofHandler.java
@@ -47,12 +47,12 @@
 import com.oracle.svm.core.feature.AutomaticallyRegisteredFeature;
 import com.oracle.svm.core.feature.InternalFeature;
 import com.oracle.svm.core.heap.RestrictHeapAccess;
+import com.oracle.svm.core.jfr.HasJfrSupport;
 import com.oracle.svm.core.jfr.JfrExecutionSamplerSupported;
 import com.oracle.svm.core.jfr.JfrFeature;
 import com.oracle.svm.core.jfr.sampler.JfrExecutionSampler;
 import com.oracle.svm.core.option.HostedOptionKey;
 import com.oracle.svm.core.option.SubstrateOptionsParser;
-import com.oracle.svm.core.posix.darwin.DarwinSubstrateSigprofHandler;
 import com.oracle.svm.core.posix.headers.Signal;
 import com.oracle.svm.core.posix.linux.LinuxSubstrateSigprofHandler;
 import com.oracle.svm.core.sampler.SubstrateSigprofHandler;
@@ -152,10 +152,14 @@ public void afterRegistration(AfterRegistrationAccess access) {
     }
 
     private static SubstrateSigprofHandler makeNewSigprofHandler() {
-        if (Platform.includedIn(Platform.LINUX.class)) {
+        /*
+         * For JFR, we should employ a global timer instead of a per-thread timer to adhere to the
+         * sampling frequency specified in .jfc.
+         */
+        if (Platform.includedIn(Platform.DARWIN.class) || HasJfrSupport.get()) {
+            return new PosixSubstrateGlobalSigprofHandler();
+        } else if (Platform.includedIn(Platform.LINUX.class)) {
             return new LinuxSubstrateSigprofHandler();
-        } else if (Platform.includedIn(Platform.DARWIN.class)) {
-            return new DarwinSubstrateSigprofHandler();
         } else {
             throw VMError.shouldNotReachHere("The JFR-based sampler is not supported on this platform.");
         }