From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Thu, 20 Sep 2012 04:33:54 +0000 (-0700)
Subject: kernel - Add lwkt_yield_quick()
X-Git-Tag: v3.2.0~107
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/405041228ac2bcf301b9dedd7aa46e88618842c5

kernel - Add lwkt_yield_quick()

* Add a quick version of lwkt_yield() which does not try to round-robin
  LWKT threads at the same priority.
---

diff --git a/sys/kern/lwkt_thread.c b/sys/kern/lwkt_thread.c
index bc6f22c2d1..7414c2c8b5 100644
--- a/sys/kern/lwkt_thread.c
+++ b/sys/kern/lwkt_thread.c
@@ -1199,6 +1199,28 @@ lwkt_yield(void)
     }
 }
 
+/*
+ * The quick version processes pending interrupts and higher-priority
+ * LWKT threads but will not round-robin same-priority LWKT threads.
+ */
+void
+lwkt_yield_quick(void)
+{
+    globaldata_t gd = mycpu;
+    thread_t td = gd->gd_curthread;
+
+    if ((gd->gd_reqflags & RQF_IDLECHECK_MASK) && td->td_nest_count < 2)
+	splz();
+    if (lwkt_resched_wanted()) {
+	if (TAILQ_FIRST(&gd->gd_tdrunq) == td) {
+	    clear_lwkt_resched();
+	} else {
+	    lwkt_schedule_self(curthread);
+	    lwkt_switch();
+	}
+    }
+}
+
 /*
  * This yield is designed for kernel threads with a user context.
  *
diff --git a/sys/sys/thread.h b/sys/sys/thread.h
index 66c126e4d2..4e244a5b5f 100644
--- a/sys/sys/thread.h
+++ b/sys/sys/thread.h
@@ -444,6 +444,7 @@ extern void lwkt_schedule_self(thread_t);
 extern void lwkt_deschedule(thread_t);
 extern void lwkt_deschedule_self(thread_t);
 extern void lwkt_yield(void);
+extern void lwkt_yield_quick(void);
 extern void lwkt_user_yield(void);
 extern void lwkt_token_wait(void);
 extern void lwkt_hold(thread_t);