From 444615f245995d9f976ea400328d1518a864d196 Mon Sep 17 00:00:00 2001
From: Carl Lerche <me@carllerche.com>
Date: Thu, 22 Jun 2023 20:03:51 +0000
Subject: [PATCH] more work

---
 .../runtime/scheduler/multi_thread/counters.rs   | 16 ++++++++++++++++
 .../src/runtime/scheduler/multi_thread/worker.rs | 11 +++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/tokio/src/runtime/scheduler/multi_thread/counters.rs b/tokio/src/runtime/scheduler/multi_thread/counters.rs
index 276894b44..edda0d46d 100644
--- a/tokio/src/runtime/scheduler/multi_thread/counters.rs
+++ b/tokio/src/runtime/scheduler/multi_thread/counters.rs
@@ -19,6 +19,8 @@ mod imp {
     static NUM_GLOBAL_QUEUE_INTERVAL: AtomicUsize = AtomicUsize::new(0);
     static NUM_NO_AVAIL_CORE: AtomicUsize = AtomicUsize::new(0);
     static NUM_RELAY_SEARCH: AtomicUsize = AtomicUsize::new(0);
+    static NUM_SPIN_STALL: AtomicUsize = AtomicUsize::new(0);
+    static NUM_NO_LOCAL_WORK: AtomicUsize = AtomicUsize::new(0);
 
     impl Drop for super::Counters {
         fn drop(&mut self) {
@@ -38,6 +40,8 @@ mod imp {
             let num_global_queue_interval = NUM_GLOBAL_QUEUE_INTERVAL.load(Relaxed);
             let num_no_avail_core = NUM_NO_AVAIL_CORE.load(Relaxed);
             let num_relay_search = NUM_RELAY_SEARCH.load(Relaxed);
+            let num_spin_stall = NUM_SPIN_STALL.load(Relaxed);
+            let num_no_local_work = NUM_NO_LOCAL_WORK.load(Relaxed);
 
             println!("---");
             println!("notifies (remote): {}", notifies_remote);
@@ -56,6 +60,8 @@ mod imp {
             println!("remote task batch: {}", num_remote_batch);
             println!("global Q interval: {}", num_global_queue_interval);
             println!("     relay search: {}", num_relay_search);
+            println!("       spin stall: {}", num_spin_stall);
+            println!("    no local work: {}", num_no_local_work);
         }
     }
 
@@ -122,6 +128,14 @@ mod imp {
     pub(crate) fn inc_num_relay_search() {
         NUM_RELAY_SEARCH.fetch_add(1, Relaxed);
     }
+
+    pub(crate) fn inc_num_spin_stall() {
+        NUM_SPIN_STALL.fetch_add(1, Relaxed);
+    }
+
+    pub(crate) fn inc_num_no_local_work() {
+        NUM_NO_LOCAL_WORK.fetch_add(1, Relaxed);
+    }
 }
 
 #[cfg(not(tokio_internal_mt_counters))]
@@ -142,6 +156,8 @@ mod imp {
     pub(crate) fn inc_global_queue_interval() {}
     pub(crate) fn inc_notify_no_core() {}
     pub(crate) fn inc_num_relay_search() {}
+    pub(crate) fn inc_num_spin_stall() {}
+    pub(crate) fn inc_num_no_local_work() {}
 }
 
 #[derive(Debug)]
diff --git a/tokio/src/runtime/scheduler/multi_thread/worker.rs b/tokio/src/runtime/scheduler/multi_thread/worker.rs
index 5ff2a3db3..dff66a377 100644
--- a/tokio/src/runtime/scheduler/multi_thread/worker.rs
+++ b/tokio/src/runtime/scheduler/multi_thread/worker.rs
@@ -700,6 +700,8 @@ impl Worker {
         // a notified task.
         core = try_task!(self.next_notified_task(cx, core));
 
+        super::counters::inc_num_no_local_work();
+
         // We consumed all work in the queues and will start searching for work.
         core.stats.end_processing_scheduled_tasks(&mut self.stats);
 
@@ -837,7 +839,7 @@ impl Worker {
     /// workers will be trying to steal at the same time.
     fn search_for_work(&mut self, cx: &Context, mut core: Box<Core>) -> NextTaskResult {
         #[cfg(not(loom))]
-        const ROUNDS: usize = 4;
+        const ROUNDS: usize = 1;
 
         #[cfg(loom)]
         const ROUNDS: usize = 1;
@@ -866,7 +868,10 @@ impl Worker {
                 return Ok((Some(task), core));
             }
 
-            std::thread::sleep(std::time::Duration::from_micros(3));
+            if i > 0 {
+                super::counters::inc_num_spin_stall();
+                std::thread::sleep(std::time::Duration::from_micros(i as u64));
+            }
 
             core = try_task_new_batch!(self, self.next_remote_task_batch(cx, core));
         }
@@ -1403,6 +1408,8 @@ impl Shared {
     }
 
     fn schedule_local(&self, cx: &Context, core: &mut Core, task: Notified) {
+        core.stats.inc_local_schedule_count();
+
         if cx.lifo_enabled.get() {
             // Push to the LIFO slot
             let prev = std::mem::replace(&mut core.lifo_slot, Some(task));