Change the decay timer default to 0.
Default to always purging, and then assume that people can change
this value if they are willing to leave a bit of PSS hanging around.
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: I7819bd8b91a1df600967fa15eebc19fa382d7ab4
diff --git a/include/jemalloc/internal/arena.h b/include/jemalloc/internal/arena.h
index 0792951..9e4bf04 100644
--- a/include/jemalloc/internal/arena.h
+++ b/include/jemalloc/internal/arena.h
@@ -30,13 +30,16 @@
purge_mode_limit = 2
} purge_mode_t;
/* ANDROID change */
-/* Use the decay mode purge method. Do not set this value to zero, since
- * forcing a purge immediately affects performance negatively. Using a
- * small value provides a compromise between performance and extra PSS.
+/* Use the decay mode purge method.
+ * Setting this value to zero results in performance issues because it
+ * causes purges at every free. Leave the default at zero, but zygote
+ * processes will set this to one using mallopt. This allows apps which
+ * tend to be active to benefit from the extra performance, but allow system
+ * servers to free PSS while they are sitting idle.
*/
#define PURGE_DEFAULT purge_mode_decay
/* Default decay time in seconds. */
-#define DECAY_TIME_DEFAULT 1
+#define DECAY_TIME_DEFAULT 0
/* End ANDROID change */
/* Number of event ticks between time checks. */
#define DECAY_NTICKS_PER_UPDATE 1000
