[src/trunk]: src/sys/kern preempt_needed(), preempt_point(): simplify the def...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b0702f13ffb9
branches:  trunk
changeset: 1008868:b0702f13ffb9
user:      ad <ad%NetBSD.org@localhost>
date:      Sat Apr 04 20:21:53 2020 +0000

description:
preempt_needed(), preempt_point(): simplify the definition of these and
key on ci_want_resched in the interests of interactive response.

diffstat:

 sys/kern/kern_synch.c |  47 ++++++++++++++++++-----------------------------
 1 files changed, 18 insertions(+), 29 deletions(-)

diffs (81 lines):

diff -r aa51172a4dd1 -r b0702f13ffb9 sys/kern/kern_synch.c
--- a/sys/kern/kern_synch.c     Sat Apr 04 20:21:26 2020 +0000
+++ b/sys/kern/kern_synch.c     Sat Apr 04 20:21:53 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_synch.c,v 1.345 2020/03/26 19:42:39 ad Exp $      */
+/*     $NetBSD: kern_synch.c,v 1.346 2020/04/04 20:21:53 ad Exp $      */
 
 /*-
  * Copyright (c) 1999, 2000, 2004, 2006, 2007, 2008, 2009, 2019, 2020
@@ -69,7 +69,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_synch.c,v 1.345 2020/03/26 19:42:39 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_synch.c,v 1.346 2020/04/04 20:21:53 ad Exp $");
 
 #include "opt_kstack.h"
 #include "opt_dtrace.h"
@@ -317,46 +317,35 @@
 }
 
 /*
- * A breathing point for long running code in kernel.
+ * Return true if the current LWP should yield the processor.  Intended to
+ * be used by long-running code in kernel.
  */
-void
-preempt_point(void)
-{
-       lwp_t *l = curlwp;
-       int needed;
-
-       KPREEMPT_DISABLE(l);
-       needed = l->l_cpu->ci_schedstate.spc_flags & SPCF_SHOULDYIELD;
-#ifndef __HAVE_FAST_SOFTINTS
-       needed |= l->l_cpu->ci_data.cpu_softints;
-#endif
-       KPREEMPT_ENABLE(l);
-
-       if (__predict_false(needed)) {
-               preempt();
-       }
-}
-
-/*
- * Check the SPCF_SHOULDYIELD flag.
- */
-bool
+inline bool
 preempt_needed(void)
 {
        lwp_t *l = curlwp;
        int needed;
 
        KPREEMPT_DISABLE(l);
-       needed = l->l_cpu->ci_schedstate.spc_flags & SPCF_SHOULDYIELD;
-#ifndef __HAVE_FAST_SOFTINTS
-       needed |= l->l_cpu->ci_data.cpu_softints;
-#endif
+       needed = l->l_cpu->ci_want_resched;
        KPREEMPT_ENABLE(l);
 
        return (bool)needed;
 }
 
 /*
+ * A breathing point for long running code in kernel.
+ */
+void
+preempt_point(void)
+{
+
+       if (__predict_false(preempt_needed())) {
+               preempt();
+       }
+}
+
+/*
  * Handle a request made by another agent to preempt the current LWP
  * in-kernel.  Usually called when l_dopreempt may be non-zero.
  *