use pause() and monmwait() with mcslocks.

Reference: /n/atom/patch/applied/mcsmwait
Date: Mon Aug 17 05:51:48 CES 2015
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/k10/l64v.s	Mon Aug 17 05:49:29 2015
+++ /sys/src/nix/k10/l64v.s	Mon Aug 17 05:49:30 2015
@@ -286,6 +286,19 @@
 	SUBL	$1, AX
 	RET
 
+TEXT ainc64(SB), 1, $-4			/* u64int ainc(u64int*) */
+	MOVQ	$1, AX
+	LOCK; XADDQ AX, (RARG)
+	ADDQ	$1, AX
+	RET
+
+TEXT aadd64(SB), 1, $-4			/* u64int aadd64(u64int*, u64int) */
+	MOVQ	v+8(FP), AX
+	MOVQ	AX, BX
+	LOCK; XADDQ AX, (RARG)
+	ADDQ	BX, AX
+	RET
+
 TEXT tas32(SB), 1, $-4
 	MOVL	$0xdeaddead, AX
 	XCHGL	AX, (RARG)			/*  */
@@ -357,19 +370,19 @@
 /*
  * uintptr monmwait(void*, uintptr)
  */
-TEXT	k10monmwait64(SB),1,$16
+TEXT	k10monmwait64(SB),1,$-4
 	MOVQ	val+8(FP), BX
 
 _mmstart:
-	CMPQ	(BP), BX			/* changed yet? */
+	CMPQ	(RARG), BX			/* changed yet? */
 	JNE	_mmdone
 
-	MOVQ	BP, AX				/* linear address to monitor */
+	MOVQ	RARG, AX				/* linear address to monitor */
 	XORQ	CX, CX				/* extensions */
 	XORQ	DX, DX				/* hints */
 	MONITOR
 
-	CMPQ	(BP), BX			/* changed yet? */
+	CMPQ	(RARG), BX			/* changed yet? */
 	JNE	_mmdone
 
 	/*XORQ	CX, CX*/			/* extensions (different from monitor) */
@@ -377,22 +390,22 @@
 	MWAIT
 						/* questionable: pop out on irq */
 _mmdone:
-	MOVQ	(BP), AX
+	MOVQ	(RARG), AX
 	RET
 
-TEXT	k10monmwait32(SB),1,$16
+TEXT	k10monmwait32(SB),1,$-4
 	MOVQ	val+8(FP), BX
 
 _mmstart32:
-	CMPL	(BP), BX			/* changed yet? */
+	CMPL	(RARG), BX			/* changed yet? */
 	JNE	_mmdone32
 
-	MOVQ	BP, AX				/* linear address to monitor */
+	MOVQ	RARG, AX			/* linear address to monitor */
 	XORQ	CX, CX				/* extensions */
 	XORQ	DX, DX				/* hints */
 	MONITOR
 
-	CMPL	(BP), BX			/* changed yet? */
+	CMPL	(RARG), BX			/* changed yet? */
 	JNE	_mmdone32
 
 	/*XORQ	CX, CX*/			/* extensions (different from monitor) */
@@ -400,7 +413,7 @@
 	MWAIT
 						/* questionable: pop out on irq */
 _mmdone32:
-	MOVL	(BP), AX
+	MOVL	(RARG), AX
 	RET
 
 TEXT mul64fract(SB), 1, $-4
--- /sys/src/nix/k10/fns.h	Mon Aug 17 05:49:32 2015
+++ /sys/src/nix/k10/fns.h	Mon Aug 17 05:49:33 2015
@@ -156,7 +156,7 @@
 u32int	nopmonmwait32(u32int*, u32int);
 u32int	k10monmwait32(u32int*, u32int);
 
-#define	monmwaitp(v, o)	monmwait64(v, o);
+#define	monmwaitp(v, o)	((void*)monmwait64((u64int*)(v), (u64int)(o)))
 u64int	(*monmwait64)(u64int*, u64int);
 u64int	nopmonmwait64(u64int*, u64int);
 u64int	k10monmwait64(u64int*, u64int);
--- /sys/src/nix/port/mcslock.c	Mon Aug 17 05:49:35 2015
+++ /sys/src/nix/port/mcslock.c	Mon Aug 17 05:49:36 2015
@@ -22,7 +22,7 @@
 		sfence();	/* ensure reader sees updated value */
 		pred->next = ql;
 		while(monmwait(&ql->locked, 1) == 1)
-			{}
+			pause();
 	}
 }
 
@@ -42,7 +42,7 @@
 	if(ql->next != nil || !casp(&lk->head, ql, nil)){
 		/* successor, wait for list to catch up */
 		while(ql->next == nil)
-			{}
+			monmwaitp(&ql->next, nil);
 		ql->next->locked = 0;
 		sfence();
 	}