From 0d1bbcd3414c66f75004c9f4b7ca3cffc293aa8a Mon Sep 17 00:00:00 2001
From: Vlad Lazar <vlad@redpanda.com>
Date: Mon, 8 Aug 2022 13:30:22 +0100
Subject: [PATCH] scheduling_group: expose usage statistics

This commit extends the public interface of scheduling_group to expose
usage statistics (e.g. runtime).
---
 include/seastar/core/scheduling.hh |  7 +++++++
 src/core/reactor.cc                | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/seastar/core/scheduling.hh b/include/seastar/core/scheduling.hh
index 0405b9ba992..96a5fcfc06a 100644
--- a/include/seastar/core/scheduling.hh
+++ b/include/seastar/core/scheduling.hh
@@ -293,6 +293,13 @@ public:
     friend unsigned internal::scheduling_group_index(scheduling_group sg) noexcept;
     friend scheduling_group internal::scheduling_group_from_index(unsigned index) noexcept;
 
+    struct stats {
+        sched_clock::duration runtime;
+        sched_clock::duration waittime;
+        sched_clock::duration starvetime;
+    };
+    stats get_stats() const noexcept;
+
     template<typename SpecificValType, typename Mapper, typename Reducer, typename Initial>
     SEASTAR_CONCEPT( requires requires(SpecificValType specific_val, Mapper mapper, Reducer reducer, Initial initial) {
         {reducer(initial, mapper(specific_val))} -> std::convertible_to<Initial>;
diff --git a/src/core/reactor.cc b/src/core/reactor.cc
index 49ed5d7d4dd..f807bdca7f3 100644
--- a/src/core/reactor.cc
+++ b/src/core/reactor.cc
@@ -4512,6 +4512,17 @@ scheduling_group::set_shares(float shares) noexcept {
     engine()._task_queues[_id]->set_shares(shares);
 }
 
+scheduling_group::stats
+scheduling_group::get_stats() const noexcept {
+    const auto * const tq = engine()._task_queues[_id].get();
+    return {
+        .runtime = tq->_runtime,
+        .waittime = tq->_waittime,
+        .starvetime = tq->_starvetime
+    };
+}
+
+
 future<scheduling_group>
 create_scheduling_group(sstring name, float shares) noexcept {
     auto aid = allocate_scheduling_group_id();