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Date:      Fri, 12 Apr 2019 00:53:31 +0000 (UTC)
From:      Justin Hibbits <jhibbits@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r346144 - in head/sys/powerpc: include powerpc
Message-ID:  <201904120053.x3C0rVj7048933@repo.freebsd.org>
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Author: jhibbits
Date: Fri Apr 12 00:53:30 2019
New Revision: 346144
URL: https://svnweb.freebsd.org/changeset/base/346144

Log:
  powerpc: Adjust priority NOPs, and make them functions
  
  PowerISA 2.07 and PowerISA 3.0 both specify special NOPs for priority
  adjustments, with "medium" priority being normal.  We had been setting
  medium-low as our normal priority.  Rather than guess each time as to what
  we want and the right NOP, wrap them in inline functions, and replace the
  occurrances of the NOPs with the functions.  Also, make DELAY() drop to very
  low priority while waiting, so we don't burn CPU.
  
  Coupled with r346143, this shaves off a modest 5-8% on buildworld times with
  -j72.  There may be more room for improvement with judicious use of these
  NOPs.
  
  MFC after:	2 weeks

Modified:
  head/sys/powerpc/include/cpufunc.h
  head/sys/powerpc/powerpc/machdep.c
  head/sys/powerpc/powerpc/mp_machdep.c

Modified: head/sys/powerpc/include/cpufunc.h
==============================================================================
--- head/sys/powerpc/include/cpufunc.h	Fri Apr 12 00:44:33 2019	(r346143)
+++ head/sys/powerpc/include/cpufunc.h	Fri Apr 12 00:53:30 2019	(r346144)
@@ -212,6 +212,43 @@ get_pcpu(void)
 	return (ret);
 }
 
+/* "NOP" operations to signify priorities to the kernel. */
+static __inline void
+nop_prio_vlow(void)
+{
+	__asm __volatile("or 31,31,31");
+}
+
+static __inline void
+nop_prio_low(void)
+{
+	__asm __volatile("or 1,1,1");
+}
+
+static __inline void
+nop_prio_mlow(void)
+{
+	__asm __volatile("or 6,6,6");
+}
+
+static __inline void
+nop_prio_medium(void)
+{
+	__asm __volatile("or 2,2,2");
+}
+
+static __inline void
+nop_prio_mhigh(void)
+{
+	__asm __volatile("or 5,5,5");
+}
+
+static __inline void
+nop_prio_high(void)
+{
+	__asm __volatile("or 3,3,3");
+}
+
 #endif /* _KERNEL */
 
 #endif /* !_MACHINE_CPUFUNC_H_ */

Modified: head/sys/powerpc/powerpc/machdep.c
==============================================================================
--- head/sys/powerpc/powerpc/machdep.c	Fri Apr 12 00:44:33 2019	(r346143)
+++ head/sys/powerpc/powerpc/machdep.c	Fri Apr 12 00:53:30 2019	(r346144)
@@ -494,7 +494,7 @@ spinlock_enter(void)
 
 	td = curthread;
 	if (td->td_md.md_spinlock_count == 0) {
-		__asm __volatile("or 2,2,2"); /* Set high thread priority */
+		nop_prio_mhigh();
 		msr = intr_disable();
 		td->td_md.md_spinlock_count = 1;
 		td->td_md.md_saved_msr = msr;
@@ -515,7 +515,7 @@ spinlock_exit(void)
 	td->td_md.md_spinlock_count--;
 	if (td->td_md.md_spinlock_count == 0) {
 		intr_restore(msr);
-		__asm __volatile("or 6,6,6"); /* Set normal thread priority */
+		nop_prio_medium();
 	}
 }
 

Modified: head/sys/powerpc/powerpc/mp_machdep.c
==============================================================================
--- head/sys/powerpc/powerpc/mp_machdep.c	Fri Apr 12 00:44:33 2019	(r346143)
+++ head/sys/powerpc/powerpc/mp_machdep.c	Fri Apr 12 00:53:30 2019	(r346144)
@@ -78,8 +78,8 @@ machdep_ap_bootstrap(void)
 	__asm __volatile("msync; isync");
 
 	while (ap_letgo == 0)
-		__asm __volatile("or 31,31,31");
-	__asm __volatile("or 6,6,6");
+		nop_prio_vlow();
+	nop_prio_medium();
 
 	/*
 	 * Set timebase as soon as possible to meet an implicit rendezvous

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