2 files changed, 20 insertions, 1 deletions

diff --git a/crates/ra_prof/Cargo.toml b/crates/ra_prof/Cargo.toml
index c33b5121a..b3d52985a 100644
--- a/crates/ra_prof/Cargo.toml
+++ b/crates/ra_prof/Cargo.toml
@@ -4,6 +4,7 @@ name = "ra_prof"
 version = "0.1.0"
 authors = ["rust-analyzer developers"]
 publish = false
+license = "MIT OR Apache-2.0"
 
 [lib]
 doctest = false
@@ -12,6 +13,7 @@ doctest = false
 ra_arena = { path = "../ra_arena" }
 once_cell = "1.3.1"
 backtrace = { version = "0.3.44", optional = true }
+mimalloc = { version = "0.1.19", default-features = false, optional = true }
 
 [target.'cfg(not(target_env = "msvc"))'.dependencies]
 jemallocator = { version = "0.3.2", optional = true }
@@ -20,3 +22,9 @@ jemalloc-ctl = { version = "0.3.3", optional = true }
 [features]
 jemalloc = [ "jemallocator", "jemalloc-ctl" ]
 cpu_profiler = []
+
+# Uncomment to enable for the whole crate graph
+# default = [ "backtrace" ]
+# default = [ "jemalloc" ]
+# default = [ "mimalloc" ]
+# default = [ "cpu_profiler" ]
diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
index 89df7f04b..b54531b4e 100644
--- a/crates/ra_prof/src/lib.rs
+++ b/crates/ra_prof/src/lib.rs
@@ -19,6 +19,10 @@ pub use crate::{
 #[global_allocator]
 static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
 
+#[cfg(all(feature = "mimalloc"))]
+#[global_allocator]
+static ALLOC: mimalloc::MiMalloc = mimalloc::MiMalloc;
+
 /// Prints backtrace to stderr, useful for debugging.
 #[cfg(feature = "backtrace")]
 pub fn print_backtrace() {
@@ -43,6 +47,7 @@ pub struct Scope {
 }
 
 impl Scope {
+    #[must_use]
     pub fn enter() -> Scope {
         let prev = IN_SCOPE.with(|slot| std::mem::replace(&mut *slot.borrow_mut(), true));
         Scope { prev }
@@ -65,7 +70,8 @@ impl Drop for Scope {
 /// 2. Build with `cpu_profiler` feature.
 /// 3. Tun the code, the *raw* output would be in the `./out.profile` file.
 /// 4. Install pprof for visualization (https://github.com/google/pprof).
-/// 5. Use something like `pprof -svg target/release/rust-analyzer ./out.profile` to see the results.
+/// 5. Bump sampling frequency to once per ms: `export CPUPROFILE_FREQUENCY=1000`
+/// 6. Use something like `pprof -svg target/release/rust-analyzer ./out.profile` to see the results.
 ///
 /// For example, here's how I run profiling on NixOS:
 ///
@@ -73,11 +79,16 @@ impl Drop for Scope {
 /// $ nix-shell -p gperftools --run \
 ///     'cargo run --release -p rust-analyzer -- parse < ~/projects/rustbench/parser.rs > /dev/null'
 /// ```
+///
+/// See this diff for how to profile completions:
+///
+/// https://github.com/rust-analyzer/rust-analyzer/pull/5306
 #[derive(Debug)]
 pub struct CpuProfiler {
     _private: (),
 }
 
+#[must_use]
 pub fn cpu_profiler() -> CpuProfiler {
     #[cfg(feature = "cpu_profiler")]
     {