Disable jemalloc decay in benches

Author: Veykril

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

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,

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]

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,

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";