From 1cf218e40f33f1f84ab5aea35ab812cfa1b46302 Mon Sep 17 00:00:00 2001
From: dillon <dillon@FreeBSD.org>
Date: Thu, 5 Jul 2001 01:32:42 +0000
Subject: Move vm_page_zero_idle() from machine-dependant sections to a
 machine-independant source file, vm/vm_zeroidle.c.  It was exactly the same
 for all platforms and updating them all was getting annoying.

---
 sys/vm/vm_zeroidle.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 sys/vm/vm_zeroidle.c

(limited to 'sys/vm')

diff --git a/sys/vm/vm_zeroidle.c b/sys/vm/vm_zeroidle.c
new file mode 100644
index 0000000..c1361de
--- /dev/null
+++ b/sys/vm/vm_zeroidle.c
@@ -0,0 +1,117 @@
+/*-
+ * Copyright (c) 1994 John Dyson
+ * Copyright (c) 2001 Matt Dillon
+ *
+ * All rights reserved.  Terms for use and redistribution
+ * are covered by the BSD Copyright as found in /usr/src/COPYRIGHT.
+ *
+ *	from: @(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
+ *	Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
+ * $FreeBSD$
+ */
+
+#include "opt_npx.h"
+#ifdef PC98
+#include "opt_pc98.h"
+#endif
+#include "opt_reset.h"
+#include "opt_isa.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/proc.h>
+#include <sys/bio.h>
+#include <sys/buf.h>
+#include <sys/vnode.h>
+#include <sys/vmmeter.h>
+#include <sys/kernel.h>
+#include <sys/ktr.h>
+#include <sys/mutex.h>
+#include <sys/smp.h>
+#include <sys/sysctl.h>
+#include <sys/unistd.h>
+
+#include <machine/cpu.h>
+#include <machine/md_var.h>
+#include <machine/pcb.h>
+#include <machine/pcb_ext.h>
+#include <machine/vm86.h>
+
+#include <vm/vm.h>
+#include <vm/vm_param.h>
+#include <sys/lock.h>
+#include <vm/vm_kern.h>
+#include <vm/vm_page.h>
+#include <vm/vm_map.h>
+#include <vm/vm_extern.h>
+
+#include <sys/user.h>
+
+#ifdef PC98
+#include <pc98/pc98/pc98.h>
+#else
+#include <i386/isa/isa.h>
+#endif
+
+SYSCTL_DECL(_vm_stats_misc);
+
+static int cnt_prezero;
+
+SYSCTL_INT(_vm_stats_misc, OID_AUTO,
+	cnt_prezero, CTLFLAG_RD, &cnt_prezero, 0, "");
+
+/*
+ * Implement the pre-zeroed page mechanism.
+ * This routine is called from the idle loop.
+ */
+
+#define ZIDLE_LO(v)	((v) * 2 / 3)
+#define ZIDLE_HI(v)	((v) * 4 / 5)
+
+int
+vm_page_zero_idle(void)
+{
+	static int free_rover;
+	static int zero_state;
+	vm_page_t m;
+
+	/*
+	 * Attempt to maintain approximately 1/2 of our free pages in a
+	 * PG_ZERO'd state.   Add some hysteresis to (attempt to) avoid
+	 * generally zeroing a page when the system is near steady-state.
+	 * Otherwise we might get 'flutter' during disk I/O / IPC or 
+	 * fast sleeps.  We also do not want to be continuously zeroing
+	 * pages because doing so may flush our L1 and L2 caches too much.
+	 */
+
+	if (zero_state && vm_page_zero_count >= ZIDLE_LO(cnt.v_free_count))
+		return(0);
+	if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count))
+		return(0);
+
+	if (mtx_trylock(&Giant)) {
+		zero_state = 0;
+		m = vm_pageq_find(PQ_FREE, free_rover, FALSE);
+		if (m != NULL && (m->flags & PG_ZERO) == 0) {
+			vm_page_queues[m->queue].lcnt--;
+			TAILQ_REMOVE(&vm_page_queues[m->queue].pl, m, pageq);
+			m->queue = PQ_NONE;
+			pmap_zero_page(VM_PAGE_TO_PHYS(m));
+			vm_page_flag_set(m, PG_ZERO);
+			m->queue = PQ_FREE + m->pc;
+			vm_page_queues[m->queue].lcnt++;
+			TAILQ_INSERT_TAIL(&vm_page_queues[m->queue].pl, m,
+			    pageq);
+			++vm_page_zero_count;
+			++cnt_prezero;
+			if (vm_page_zero_count >= ZIDLE_HI(cnt.v_free_count))
+				zero_state = 1;
+		}
+		free_rover = (free_rover + PQ_PRIME2) & PQ_L2_MASK;
+		mtx_unlock(&Giant);
+		return (1);
+	}
+	return(0);
+}
+
-- 
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