From 322d41a2b01d70462fd2fa6a96d70b06a423e78b Mon Sep 17 00:00:00 2001
From: AptRock327 <dominik032009@gmail.com>
Date: Mon, 22 Jul 2024 22:50:29 +0200
Subject: kernel: sched: Implement MLFQ
Implements the Multilevel Feedback Queue scheduling algorithm.
Signed-off-by: AptRock327 <dominik032009@gmail.com>
Signed-off-by: Ian Moffett <ian@osmora.org>
---
sys/include/sys/proc.h | 1 +
sys/include/sys/sched.h | 1 +
sys/kern/kern_sched.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 51 insertions(+)
(limited to 'sys')
diff --git a/sys/include/sys/proc.h b/sys/include/sys/proc.h
index ed75f71..b9db603 100644
--- a/sys/include/sys/proc.h
+++ b/sys/include/sys/proc.h
@@ -56,6 +56,7 @@ struct proc {
struct trapframe tf;
struct pcb pcb;
size_t priority;
+ bool rested;
uint32_t flags;
uintptr_t stack_base;
TAILQ_ENTRY(proc) link;
diff --git a/sys/include/sys/sched.h b/sys/include/sys/sched.h
index 52ca1ba..829e57d 100644
--- a/sys/include/sys/sched.h
+++ b/sys/include/sys/sched.h
@@ -36,6 +36,7 @@
#if defined(_KERNEL)
void sched_init(void);
+void sched_yield(void);
__dead void sched_enter(void);
void sched_enqueue_td(struct proc *td);
diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
index 1d79937..6d85330 100644
--- a/sys/kern/kern_sched.c
+++ b/sys/kern/kern_sched.c
@@ -140,6 +140,38 @@ this_td(void)
return ci->curtd;
}
+static inline void
+td_pri_raise(struct proc *td)
+{
+ if (td->priority > 0) {
+ td->priority--;
+ }
+}
+
+static inline void
+td_pri_lower(struct proc *td)
+{
+ if (td->priority < SCHED_NQUEUE - 1) {
+ td->priority++;
+ }
+}
+
+static inline void
+td_pri_update(struct proc *td)
+{
+ switch (policy) {
+ case SCHED_POLICY_MLFQ:
+ if (td->rested) {
+ td->rested = false;
+ td_pri_raise(td);
+ } else {
+ td_pri_lower(td);
+ }
+
+ break;
+ }
+}
+
/*
* Perform a context switch.
*/
@@ -154,6 +186,10 @@ sched_switch(struct trapframe *tf)
ci = this_cpu();
td = ci->curtd;
+ if (td != NULL) {
+ td_pri_update(td);
+ }
+
/*
* Get the next thread and use it only if it isn't
* in the middle of an exit, exec, or whatever.
@@ -204,6 +240,19 @@ sched_enter(void)
for (;;);
}
+void
+sched_yield(void)
+{
+ struct proc *td = this_td();
+
+ if (td != NULL) {
+ td->rested = true;
+ }
+
+ sched_oneshot(false);
+ while (td->rested);
+}
+
void
sched_init(void)
{
--
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