From e601787ca2619209aa1f254940ef716376bc9031 Mon Sep 17 00:00:00 2001
From: Jiajie Chen <c@jia.je>
Date: Thu, 9 Jul 2020 12:50:06 +0800
Subject: [PATCH] Only yield for timer interrupt

---
 kernel/src/arch/mipsel/interrupt/mod.rs | 2 +-
 kernel/src/process/thread.rs            | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/src/arch/mipsel/interrupt/mod.rs b/kernel/src/arch/mipsel/interrupt/mod.rs
index 43b47586..6b845f49 100644
--- a/kernel/src/arch/mipsel/interrupt/mod.rs
+++ b/kernel/src/arch/mipsel/interrupt/mod.rs
@@ -194,7 +194,7 @@ pub fn handle_reserved_inst(tf: &mut UserContext) -> bool {
             let tls = tf.tls;
 
             set_trapframe_register(rt, tls, tf);
-            debug!("Read TLS by rdhwr {:x} to register {:?}", tls, rt);
+            trace!("Read TLS by rdhwr {:x} to register {:?}", tls, rt);
             tf.epc = tf.epc + 4;
             return true;
         } else {
diff --git a/kernel/src/process/thread.rs b/kernel/src/process/thread.rs
index 82869205..3891aae2 100644
--- a/kernel/src/process/thread.rs
+++ b/kernel/src/process/thread.rs
@@ -510,6 +510,7 @@ pub fn spawn(thread: Arc<Thread>) {
             trace!("back from user: {:#x?} trap_num {:#x}", cx, trap_num);
 
             let mut exit = false;
+            let mut do_yield = false;
             match trap_num {
                 // must be first
                 _ if is_page_fault(trap_num) => {
@@ -527,6 +528,7 @@ pub fn spawn(thread: Arc<Thread>) {
                     crate::arch::interrupt::ack(trap_num);
                     trace!("handle irq {:#x}", trap_num);
                     if is_timer_intr(trap_num) {
+                        do_yield = true;
                         crate::arch::interrupt::timer();
                     }
                     IRQ_MANAGER.read().try_handle_interrupt(Some(trap_num));
@@ -556,7 +558,7 @@ pub fn spawn(thread: Arc<Thread>) {
             if exit {
                 info!("thread {} stopped", thread.tid);
                 break;
-            } else {
+            } else if do_yield {
                 yield_now().await;
             }
         }