Everywhere: Make tracking cpu usage independent from system ticks

This switches tracking CPU usage to more accurately measure time in
user and kernel land using either the TSC or another time source.
This will also come in handy when implementing a tickless kernel mode.

1 files changed, 23 insertions, 0 deletions

diff --git a/Kernel/Thread.cpp b/Kernel/Thread.cpp
index b3e0b53158..6d5111a1bd 100644
--- a/Kernel/Thread.cpp
+++ b/Kernel/Thread.cpp
@@ -567,6 +567,29 @@ void Thread::finalize_dying_threads()
     }
 }
 
+void Thread::update_time_scheduled(u64 current_scheduler_time, bool is_kernel, bool no_longer_running)
+{
+    if (m_last_time_scheduled.has_value()) {
+        u64 delta;
+        if (current_scheduler_time >= m_last_time_scheduled.value())
+            delta = current_scheduler_time - m_last_time_scheduled.value();
+        else
+            delta = m_last_time_scheduled.value() - current_scheduler_time; // the unlikely event that the clock wrapped
+        if (delta != 0) {
+            // Add it to the global total *before* updating the thread's value!
+            Scheduler::add_time_scheduled(delta, is_kernel);
+
+            auto& total_time = is_kernel ? m_total_time_scheduled_kernel : m_total_time_scheduled_user;
+            ScopedSpinLock scheduler_lock(g_scheduler_lock);
+            total_time += delta;
+        }
+    }
+    if (no_longer_running)
+        m_last_time_scheduled = {};
+    else
+        m_last_time_scheduled = current_scheduler_time;
+}
+
 bool Thread::tick()
 {
     if (previous_mode() == PreviousMode::KernelMode) {