commit a1c0d2fd4ce96e123c4ae6506c9d637d747e1fe2
author Christopher Ferris <cferris@google.com> Mon May 15 15:50:19 2017 -0700
committer Christopher Ferris <cferris@google.com> Mon May 15 16:59:16 2017 -0700
tree b1f89edbd67d6b09b9cbdfb1bf03b65b2dac9ad4
parent ac58d33d343eba6a3370f541467f09802c48b24b

Add support for modifying decay timer.

Add the mallopt function, and only a single option so far.

Bug: 36401135

Test: Built and booted bullhead.
Test: Ran jemalloc unit tests.
Test: Ran bionic unit tests.
Test: Ran a test that allocated and free'd a large piece of memory,
Test: and verified that after changing the parameter, the PSS
Test: sticks around (decay timer set to 1), the PSS is purged (decay
Test: timer set to 0).
Change-Id: I6927929b0c539c1023d34772d9e26bb6a8a45877

libc/bionic/jemalloc.h

diff --git a/libc/bionic/jemalloc.h b/libc/bionic/jemalloc.h
index fceb323..f7e8770 100644
--- a/libc/bionic/jemalloc.h
+++ b/libc/bionic/jemalloc.h
@@ -26,6 +26,7 @@
 __BEGIN_DECLS
 
 struct mallinfo je_mallinfo();
+int je_mallopt(int, int);
 int je_iterate(uintptr_t, size_t, void (*)(uintptr_t, size_t, void*), void*);
 void je_malloc_disable();
 void je_malloc_enable();

libc/bionic/jemalloc_wrapper.cpp

diff --git a/libc/bionic/jemalloc_wrapper.cpp b/libc/bionic/jemalloc_wrapper.cpp
index e33d560..266b966 100644
--- a/libc/bionic/jemalloc_wrapper.cpp
+++ b/libc/bionic/jemalloc_wrapper.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <malloc.h>
 #include <sys/param.h>
 #include <unistd.h>
 
@@ -46,3 +47,38 @@
   }
   return je_memalign(boundary, size);
 }
+
+int je_mallopt(int param, int value) {
+  // The only parameter we currently understand is M_DECAY_TIME.
+  if (param == M_DECAY_TIME) {
+    // Only support setting the value to 1 or 0.
+    ssize_t decay_time;
+    if (value) {
+      decay_time = 1;
+    } else {
+      decay_time = 0;
+    }
+    // First get the total number of arenas.
+    unsigned narenas;
+    size_t sz = sizeof(unsigned);
+    if (je_mallctl("arenas.narenas", &narenas, &sz, nullptr, 0) != 0) {
+      return 0;
+    }
+
+    // Set the decay time for any arenas that will be created in the future.
+    if (je_mallctl("arenas.decay_time", nullptr, nullptr, &decay_time, sizeof(decay_time)) != 0) {
+      return 0;
+    }
+
+    // Change the decay on the already existing arenas.
+    char buffer[100];
+    for (unsigned i = 0; i < narenas; i++) {
+      snprintf(buffer, sizeof(buffer), "arena.%d.decay_time", i);
+      if (je_mallctl(buffer, nullptr, nullptr, &decay_time, sizeof(decay_time)) != 0) {
+        break;
+      }
+    }
+    return 1;
+  }
+  return 0;
+}

libc/bionic/malloc_common.cpp

diff --git a/libc/bionic/malloc_common.cpp b/libc/bionic/malloc_common.cpp
index 18c998d..1f201d1 100644
--- a/libc/bionic/malloc_common.cpp
+++ b/libc/bionic/malloc_common.cpp
@@ -68,6 +68,7 @@
     Malloc(iterate),
     Malloc(malloc_disable),
     Malloc(malloc_enable),
+    Malloc(mallopt),
   };
 
 // In a VM process, this is set to 1 after fork()ing out of zygote.
@@ -101,6 +102,14 @@
   return Malloc(mallinfo)();
 }
 
+extern "C" int mallopt(int param, int value) {
+  auto _mallopt = __libc_globals->malloc_dispatch.mallopt;
+  if (__predict_false(_mallopt != nullptr)) {
+    return _mallopt(param, value);
+  }
+  return Malloc(mallopt)(param, value);
+}
+
 extern "C" void* malloc(size_t bytes) {
   auto _malloc = __libc_globals->malloc_dispatch.malloc;
   if (__predict_false(_malloc != nullptr)) {
@@ -247,6 +256,10 @@
                                           prefix, "mallinfo")) {
     return false;
   }
+  if (!InitMallocFunction<MallocMallopt>(malloc_impl_handler, &table->mallopt,
+                                         prefix, "mallopt")) {
+    return false;
+  }
   if (!InitMallocFunction<MallocMalloc>(malloc_impl_handler, &table->malloc,
                                         prefix, "malloc")) {
     return false;