From 196f5066228d908cbac060396a1aba557efe1ef3 Mon Sep 17 00:00:00 2001
From: Pedro Martelletto <pedro@cvs.openbsd.org>
Date: Sat, 26 May 2007 20:26:52 +0000
Subject: Dynamic buffer cache. Initial diff from mickey@, okay art@ beck@
 toby@ deraadt@ dlg@.

---
 sys/arch/aviion/aviion/machdep.c | 88 +++++-----------------------------------
 1 file changed, 10 insertions(+), 78 deletions(-)

(limited to 'sys/arch/aviion')

diff --git a/sys/arch/aviion/aviion/machdep.c b/sys/arch/aviion/aviion/machdep.c
index fe4951338b7..eb4b2527e0a 100644
--- a/sys/arch/aviion/aviion/machdep.c
+++ b/sys/arch/aviion/aviion/machdep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: machdep.c,v 1.6 2007/05/12 20:03:22 miod Exp $	*/
+/* $OpenBSD: machdep.c,v 1.7 2007/05/26 20:26:50 pedro Exp $	*/
 /*
  * Copyright (c) 1998, 1999, 2000, 2001 Steve Murphree, Jr.
  * Copyright (c) 1996 Nivas Madhur
@@ -116,12 +116,6 @@ __cpu_simple_lock_t cpu_mutex = __SIMPLELOCK_UNLOCKED;
 /*
  * Declare these as initialized data so we can patch them.
  */
-#ifdef	NBUF
-int nbuf = NBUF;
-#else
-int nbuf = 0;
-#endif
-
 #ifndef BUFCACHEPERCENT
 #define BUFCACHEPERCENT 5
 #endif
@@ -269,49 +263,17 @@ cpu_startup()
 	platform->startup();
 
 	/*
-	 * Now allocate buffers proper.  They are different than the above
-	 * in that they usually occupy more virtual memory than physical.
+	 * Determine how many buffers to allocate.
+	 * We allocate bufcachepercent% of memory for buffer space.
 	 */
-	size = MAXBSIZE * nbuf;
-	if (uvm_map(kernel_map, (vaddr_t *) &buffers, round_page(size),
-	    NULL, UVM_UNKNOWN_OFFSET, 0, UVM_MAPFLAG(UVM_PROT_NONE,
-	      UVM_PROT_NONE, UVM_INH_NONE, UVM_ADV_NORMAL, 0)))
-		panic("cpu_startup: cannot allocate VM for buffers");
-	minaddr = (vaddr_t)buffers;
-
-	if ((bufpages / nbuf) >= btoc(MAXBSIZE)) {
-		/* don't want to alloc more physical mem than needed */
-		bufpages = btoc(MAXBSIZE) * nbuf;
-	}
-	base = bufpages / nbuf;
-	residual = bufpages % nbuf;
-
-	for (i = 0; i < nbuf; i++) {
-		vsize_t curbufsize;
-		vaddr_t curbuf;
-		struct vm_page *pg;
+	if (bufpages == 0)
+		bufpages = physmem * bufcachepercent / 100;
 
-		/*
-		 * Each buffer has MAXBSIZE bytes of VM space allocated.  Of
-		 * that MAXBSIZE space, we allocate and map (base+1) pages
-		 * for the first "residual" buffers, and then we allocate
-		 * "base" pages for the rest.
-		 */
-		curbuf = (vaddr_t)buffers + (i * MAXBSIZE);
-		curbufsize = PAGE_SIZE * ((i < residual) ? (base + 1) : base);
-
-		while (curbufsize) {
-			pg = uvm_pagealloc(NULL, 0, NULL, 0);
-			if (pg == NULL)
-				panic("cpu_startup: not enough memory for "
-				      "buffer cache");
-			pmap_kenter_pa(curbuf, VM_PAGE_TO_PHYS(pg),
-			    VM_PROT_READ | VM_PROT_WRITE);
-			curbuf += PAGE_SIZE;
-			curbufsize -= PAGE_SIZE;
-		}
-	}
-	pmap_update(pmap_kernel());
+	/* Restrict to at most 25% filled kvm */
+	if (bufpages >
+	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
+		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
+		    PAGE_SIZE / 4;
 
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
@@ -327,8 +289,6 @@ cpu_startup()
 	    VM_PHYS_SIZE, 0, FALSE, NULL);
 
 	printf("avail mem = %ld (%d pages)\n", ptoa(uvmexp.free), uvmexp.free);
-	printf("using %d buffers containing %d bytes of memory\n", nbuf,
-	    bufpages * PAGE_SIZE);
 
 	/*
 	 * Set up buffers, so they can be used to read disk labels.
@@ -377,34 +337,6 @@ allocsys(v)
 	valloc(msqids, struct msqid_ds, msginfo.msgmni);
 #endif
 
-	/*
-	 * Determine how many buffers to allocate.  We use 10% of the
-	 * first 2MB of memory, and 5% of the rest, with a minimum of 16
-	 * buffers.  We allocate 1/2 as many swap buffer headers as file
-	 * i/o buffers.
-	 */
-	if (bufpages == 0) {
-		bufpages = (btoc(2 * 1024 * 1024) + physmem) *
-		    bufcachepercent / 100;
-	}
-	if (nbuf == 0) {
-		nbuf = bufpages;
-		if (nbuf < 16)
-			nbuf = 16;
-	}
-
-	/* Restrict to at most 70% filled kvm */
-	if (nbuf >
-	    (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / MAXBSIZE * 7 / 10)
-		nbuf = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
-		    MAXBSIZE * 7 / 10;
-
-	/* More buffer pages than fits into the buffers is senseless.  */
-	if (bufpages > nbuf * MAXBSIZE / PAGE_SIZE)
-		bufpages = nbuf * MAXBSIZE / PAGE_SIZE;
-
-	valloc(buf, struct buf, nbuf);
-
 	return v;
 }
 
-- 
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