From b195eb6c80c93d5e180a67e5351d497ab9f4cdc9 Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukastw97@gmail.com>
Date: Mon, 24 Feb 2025 14:38:16 +0100
Subject: [PATCH] Disable jemalloc decay in benches

---
 Cargo.toml                              |  3 +++
 benches/accumulator.rs                  |  2 ++
 benches/compare.rs                      |  2 ++
 benches/incremental.rs                  |  2 ++
 benches/shims/global_alloc_overwrite.rs | 29 +++++++++++++++++++++++++
 5 files changed, 38 insertions(+)
 create mode 100644 benches/shims/global_alloc_overwrite.rs

diff --git a/Cargo.toml b/Cargo.toml
index 67c3475dd..d6550b175 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -50,6 +50,9 @@ rustversion = "1.0"
 test-log = { version = "0.2.11", features = ["trace"] }
 trybuild = "1.0"
 
+[target.'cfg(all(not(target_os = "windows"), not(target_os = "openbsd"), any(target_arch = "x86_64", target_arch = "aarch64", target_arch = "powerpc64")))'.dev-dependencies]
+tikv-jemallocator = "0.6.0"
+
 [[bench]]
 name = "compare"
 harness = false
diff --git a/benches/accumulator.rs b/benches/accumulator.rs
index b1a461e89..90c8781d2 100644
--- a/benches/accumulator.rs
+++ b/benches/accumulator.rs
@@ -3,6 +3,8 @@ use std::hint::black_box;
 use codspeed_criterion_compat::{criterion_group, criterion_main, BatchSize, Criterion};
 use salsa::Accumulator;
 
+include!("shims/global_alloc_overwrite.rs");
+
 #[salsa::input]
 struct Input {
     expressions: usize,
diff --git a/benches/compare.rs b/benches/compare.rs
index 6f8b7ee13..4e1cf73cd 100644
--- a/benches/compare.rs
+++ b/benches/compare.rs
@@ -6,6 +6,8 @@ use codspeed_criterion_compat::{
 };
 use salsa::Setter;
 
+include!("shims/global_alloc_overwrite.rs");
+
 #[salsa::input]
 pub struct Input {
     #[return_ref]
diff --git a/benches/incremental.rs b/benches/incremental.rs
index 7fa992682..76796a5bf 100644
--- a/benches/incremental.rs
+++ b/benches/incremental.rs
@@ -3,6 +3,8 @@ use std::hint::black_box;
 use codspeed_criterion_compat::{criterion_group, criterion_main, BatchSize, Criterion};
 use salsa::Setter;
 
+include!("shims/global_alloc_overwrite.rs");
+
 #[salsa::input]
 struct Input {
     field: usize,
diff --git a/benches/shims/global_alloc_overwrite.rs b/benches/shims/global_alloc_overwrite.rs
new file mode 100644
index 000000000..e3b5ea74f
--- /dev/null
+++ b/benches/shims/global_alloc_overwrite.rs
@@ -0,0 +1,29 @@
+#[cfg(all(
+    not(target_os = "windows"),
+    not(target_os = "openbsd"),
+    any(
+        target_arch = "x86_64",
+        target_arch = "aarch64",
+        target_arch = "powerpc64"
+    )
+))]
+#[global_allocator]
+static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
+
+// Disable decay after 10s because it can show up as *random* slow allocations
+// in benchmarks. We don't need purging in benchmarks because it isn't important
+// to give unallocated pages back to the OS.
+// https://jemalloc.net/jemalloc.3.html#opt.dirty_decay_ms
+#[cfg(all(
+    not(target_os = "windows"),
+    not(target_os = "openbsd"),
+    any(
+        target_arch = "x86_64",
+        target_arch = "aarch64",
+        target_arch = "powerpc64"
+    )
+))]
+#[allow(non_upper_case_globals)]
+#[export_name = "_rjem_malloc_conf"]
+#[allow(unsafe_code)]
+pub static _rjem_malloc_conf: &[u8] = b"dirty_decay_ms:-1,muzzy_decay_ms:-1\0";