Bug 1812452 - Increase the min profiler buffer limit to 128MiB r=florian,geckoview-reviewers,m_kato

Differential Revision: https://phabricator.services.mozilla.com/D181654

mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoThread.java

@@ -695,20 +695,21 @@ public class GeckoThread extends Thread {
     // Putting default values for now, but they can be overwritten.
     // Keep these values in sync with profiler defaults.
     int interval = 1;
-    // 8M entries. Keep this in sync with `PROFILER_DEFAULT_STARTUP_ENTRIES`.
-    int capacity = 8 * 1024 * 1024;
-    // We have a default 8M of entries but user can actually put less entries
-    // with environment variables. But even though user can put anything, we
-    // have a hard cap on the minimum value count, because if it's lower than
-    // this value, profiler could not capture anything meaningful.
+
+    // The default capacity value is the same with the min capacity, but users
+    // can still enter a different capacity. We also keep this variable to make
+    // sure that the entered value is not below the min capacity.
     // This value is kept in `scMinimumBufferEntries` variable in the cpp side:
     // https://searchfox.org/mozilla-central/rev/fa7f47027917a186fb2052dee104cd06c21dd76f/tools/profiler/core/platform.cpp#749
-    // This number is not clear in the cpp code at first, so lets calculate:
-    // scMinimumBufferEntries = scMinimumBufferSize / scBytesPerEntry
-    // expands into
-    // scMinimumNumberOfChunks * 2 * scExpectedMaximumStackSize / scBytesPerEntry
-    // and this is: 4 * 2 * 64 * 1024 / 8 = 65536 (~512 kb)
-    final int minCapacity = 65536;
+    // This number represents 128MiB in entry size.
+    // This is calculated as:
+    // 128 * 1024 * 1024 / 8 = 16777216
+    final int minCapacity = 16777216;
+
+    // ~16M entries which is 128MiB in entry size.
+    // Keep this in sync with `PROFILER_DEFAULT_STARTUP_ENTRIES`.
+    // It's computed as 16 * 1024 * 1024 there, which is the same number.
+    int capacity = minCapacity;
 
     // Set the default value of no filters - an empty array - which is safer than using null.
     // If we find a user provided value, this will be overwritten.

mozglue/baseprofiler/public/BaseProfiler.h

@@ -117,9 +117,9 @@ class SpliceableJSONWriter;
 
 static constexpr PowerOfTwo32 BASE_PROFILER_DEFAULT_ENTRIES =
 #  if !defined(GP_PLAT_arm_android)
-    MakePowerOfTwo32<8 * 1024 * 1024>();  // 8M entries = 64MB
+    MakePowerOfTwo32<16 * 1024 * 1024>();  // 16M entries = 128MiB
 #  else
-    MakePowerOfTwo32<2 * 1024 * 1024>();           // 2M entries = 16MB
+    MakePowerOfTwo32<4 * 1024 * 1024>();            // 4M entries = 32MiB
 #  endif
 
 // Startup profiling usually need to capture more data, especially on slow
@@ -128,9 +128,9 @@ static constexpr PowerOfTwo32 BASE_PROFILER_DEFAULT_ENTRIES =
 // https://searchfox.org/mozilla-central/source/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoThread.java
 static constexpr PowerOfTwo32 BASE_PROFILER_DEFAULT_STARTUP_ENTRIES =
 #  if !defined(GP_PLAT_arm_android)
-    mozilla::MakePowerOfTwo32<64 * 1024 * 1024>();  // 64M entries = 512MB
+    mozilla::MakePowerOfTwo32<64 * 1024 * 1024>();  // 64M entries = 512MiB
 #  else
-    mozilla::MakePowerOfTwo32<8 * 1024 * 1024>();  // 8M entries = 64MB
+    mozilla::MakePowerOfTwo32<16 * 1024 * 1024>();  // 16M entries = 128MiB
 #  endif
 
 // Note: Keep in sync with GeckoThread.maybeStartGeckoProfiler:

mozglue/baseprofiler/public/ProfilerBufferSize.h

@@ -35,10 +35,8 @@ constexpr static uint32_t scMinimumNumberOfChunks = 4;
 //   Firefox processes).
 constexpr static uint32_t scMaximumChunkSize = 1024 * 1024;
 
-// We should be able to store at least the minimum number of the smallest-
-// possible chunks.
-constexpr static uint32_t scMinimumBufferSize =
-    scMinimumNumberOfChunks * scMinimumChunkSize;
+// Limit to 128MiB as a lower buffer size usually isn't enough.
+constexpr static uint32_t scMinimumBufferSize = 128u * 1024u * 1024u;
 // Note: Keep in sync with GeckoThread.maybeStartGeckoProfiler:
 // https://searchfox.org/mozilla-central/source/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoThread.java
 constexpr static uint32_t scMinimumBufferEntries =