From d090a7886d0168d1e81a46865e63b34199be520d Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Sat, 12 Dec 2020 05:02:23 -0800
Subject: [PATCH] kern: add kernel thread utilization debug

---
 .../source/kern_k_dump_object.cpp             | 75 ++++++++++++++++++-
 1 file changed, 74 insertions(+), 1 deletion(-)

diff --git a/libraries/libmesosphere/source/kern_k_dump_object.cpp b/libraries/libmesosphere/source/kern_k_dump_object.cpp
index 628d3e869..6582a8143 100644
--- a/libraries/libmesosphere/source/kern_k_dump_object.cpp
+++ b/libraries/libmesosphere/source/kern_k_dump_object.cpp
@@ -252,6 +252,13 @@ namespace ams::kern::KDumpObject {
             }
         }
 
+        ALWAYS_INLINE s64 GetTickOrdered() {
+            __asm__ __volatile__("" ::: "memory");
+            const s64 tick = KHardwareTimer::GetTick();
+            __asm__ __volatile__("" ::: "memory");
+            return tick;
+        }
+
     }
 
     void DumpThread() {
@@ -648,7 +655,73 @@ namespace ams::kern::KDumpObject {
     }
 
     void DumpKernelCpuUtilization() {
-        /* TODO */
+        MESOSPHERE_RELEASE_LOG("Dump Kernel Cpu Utilization\n");
+
+        constexpr size_t MaxLogDepth = 64;
+        {
+            /* Create tracking arrays. */
+            KAutoObject *objects[MaxLogDepth];
+            u32 cpu_time[MaxLogDepth];
+
+            s64 start_tick;
+            size_t i, n;
+            KDpcManager::Sync();
+            {
+                /* Lock the thread list. */
+                KThread::ListAccessor accessor;
+
+                /* Begin tracking. */
+                start_tick = GetTickOrdered();
+
+                /* Iterate, finding kernel threads. */
+                const auto end = accessor.end();
+                i = 0;
+                for (auto it = accessor.begin(); it != end; ++it) {
+                    KThread *thread = static_cast<KThread *>(std::addressof(*it));
+                    if (KProcess *process = thread->GetOwnerProcess(); process == nullptr) {
+                        if (AMS_LIKELY(i < MaxLogDepth)) {
+                            if (AMS_LIKELY(thread->Open())) {
+                                cpu_time[i] = thread->GetCpuTime();
+                                objects[i]  = thread;
+                                ++i;
+                            }
+                        }
+                    }
+                }
+
+                /* Keep track of how many kernel threads we found. */
+                n = i;
+            }
+
+            /* Wait one second. */
+            const s64 timeout = KHardwareTimer::GetTick() + ams::svc::Tick(TimeSpan::FromSeconds(1));
+            GetCurrentThread().Sleep(timeout);
+            KDpcManager::Sync();
+
+            /* Update our metrics. */
+            for (i = 0; i < n; ++i) {
+                KThread *thread = static_cast<KThread *>(objects[i]);
+                cpu_time[i] = thread->GetCpuTime() - cpu_time[i];
+            }
+
+            /* End tracking. */
+            const s64 end_tick = GetTickOrdered();
+
+            /* Log thread utilization. */
+            for (i = 0; i < n; ++i) {
+                KThread *thread = static_cast<KThread *>(objects[i]);
+                const s64 t = static_cast<u64>(cpu_time[i]) * 1000 / (end_tick - start_tick);
+
+                MESOSPHERE_RELEASE_LOG("tid=%3lu (kernel) %3lu.%lu%% pri=%2d af=%lx\n", thread->GetId(), t / 10, t % 10, thread->GetPriority(), thread->GetAffinityMask().GetAffinityMask());
+            }
+
+            /* Close all objects. */
+            for (i = 0; i < n; ++i) {
+                objects[i]->Close();
+            }
+        }
+
+        MESOSPHERE_RELEASE_LOG("\n");
     }
 
     void DumpCpuUtilization() {