From 8534cd7f0c9474883202ff5ed66b1b0d5d0f8859 Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <edy.burt@gmail.com>
Date: Thu, 24 Sep 2020 20:17:21 +0300
Subject: [PATCH] [experiment/perf] Disable jemalloc's time-delayed purging,
 for extra determinism.

---
 compiler/rustc/src/main.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/compiler/rustc/src/main.rs b/compiler/rustc/src/main.rs
index 6bc5aa6382c4c..eafe62d316aa9 100644
--- a/compiler/rustc/src/main.rs
+++ b/compiler/rustc/src/main.rs
@@ -24,6 +24,12 @@ fn main() {
         static _F5: unsafe extern "C" fn(*mut c_void, usize) -> *mut c_void = jemalloc_sys::realloc;
         #[used]
         static _F6: unsafe extern "C" fn(*mut c_void) = jemalloc_sys::free;
+
+        // HACK(eddyb) disable time-delayed purging to remove the main (only?)
+        // source of non-determinism in `jemalloc`.
+        #[used]
+        #[export_name = "malloc_conf"]
+        static MALLOC_CONF: &'static [u8; 34] = b"dirty_decay_ms:0,muzzy_decay_ms:0\0";
     }
 
     rustc_driver::set_sigpipe_handler();