Bug 1670188 - pt 2. Add a tool that prints the run lengths for size classes r=glandium

This new program prints the jemalloc configuration, it is only built for
--enable-project=memory

Differential Revision: https://phabricator.services.mozilla.com/D93184

memory/build/mozjemalloc.cpp

@@ -4330,6 +4330,7 @@ inline void MozJemalloc::jemalloc_stats_internal(
           aBinStats[j].bytes_unused += bin_unused;
           aBinStats[j].bytes_total +=
               bin->mNumRuns * (bin->mRunSize - bin->mRunFirstRegionOffset);
+          aBinStats[j].bytes_per_run = bin->mRunSize;
         }
       }
     }

memory/build/mozjemalloc_types.h

@@ -106,7 +106,7 @@ typedef struct {
   size_t num_runs;           // The number of runs in this bin
   size_t bytes_unused;       // The unallocated bytes across all these bins
   size_t bytes_total;        // The total storage area for runs in this bin,
-                             // excluding headers..
+  size_t bytes_per_run;      // The number of bytes per run, including headers.
 } jemalloc_bin_stats_t;
 
 #define JEMALLOC_MAX_STATS_BINS 40

memory/moz.build

@@ -11,8 +11,12 @@ DIRS += [
     "build",
 ]
 
-# For now, don't build mozalloc when building with --enable-project=memory
+if CONFIG["MOZ_BUILD_APP"] == "memory":
-if CONFIG["MOZ_BUILD_APP"] != "memory":
+    DIRS += [
+        "mozjemalloc_info",
+    ]
+else:
+    # For now, don't build mozalloc when building with --enable-project=memory
     DIRS += [
         "mozalloc",
     ]

memory/mozjemalloc_info/MozjemallocInfo.cpp

@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "mozmemory.h"
+
+/*
+ * Print the configured size classes which we can then use to update
+ * documentation.
+ */
+int main() {
+  jemalloc_stats_t stats;
+  jemalloc_bin_stats_t bin_stats[JEMALLOC_MAX_STATS_BINS];
+
+  jemalloc_stats(&stats, bin_stats);
+
+  printf("Page size:    %5zu\n", stats.page_size);
+  printf("Chunk size:   %5zuKiB\n", stats.chunksize / 1024);
+
+  printf("Quantum:      %5zu\n", stats.quantum);
+  printf("Quantum max:  %5zu\n", stats.quantum_max);
+  printf("Sub-page max: %5zu\n", stats.page_size / 2);
+  printf("Large max:    %5zuKiB\n", stats.large_max / 1024);
+
+  printf("\nBin stats:\n");
+  for (auto& bin : bin_stats) {
+    if (bin.size) {
+      printf("  Bin %5zu has runs of %3zuKiB\n", bin.size,
+             bin.bytes_per_run / 1024);
+    }
+  }
+
+  return EXIT_SUCCESS;
+}

memory/mozjemalloc_info/moz.build

@@ -0,0 +1,26 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+Program("mozjemalloc-info")
+
+SOURCES += [
+    "/mfbt/Assertions.cpp",
+    "/mfbt/RandomNum.cpp",
+    "MozjemallocInfo.cpp",
+]
+
+# Link replace-malloc and the default allocator.
+USE_LIBS += [
+    "memory",
+]
+
+# The memory library defines this, so it's needed here too.
+DEFINES["IMPL_MFBT"] = True
+
+if CONFIG["MOZ_NEEDS_LIBATOMIC"]:
+    OS_LIBS += ["atomic"]
+
+DisableStlWrapping()