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[src/trunk]: src/sys bring in blist from freebsd as-is.
details: https://anonhg.NetBSD.org/src/rev/2010bcf18cea
branches: trunk
changeset: 580042:2010bcf18cea
user: yamt <yamt%NetBSD.org@localhost>
date: Wed Apr 06 11:32:06 2005 +0000
description:
bring in blist from freebsd as-is.
diffstat:
sys/kern/subr_blist.c | 1098 +++++++++++++++++++++++++++++++++++++++++++++++++
sys/sys/blist.h | 103 ++++
2 files changed, 1201 insertions(+), 0 deletions(-)
diffs (truncated from 1209 to 300 lines):
diff -r e00550d32708 -r 2010bcf18cea sys/kern/subr_blist.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/sys/kern/subr_blist.c Wed Apr 06 11:32:06 2005 +0000
@@ -0,0 +1,1098 @@
+/*-
+ * Copyright (c) 1998 Matthew Dillon. All Rights Reserved.
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+ * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*
+ * BLIST.C - Bitmap allocator/deallocator, using a radix tree with hinting
+ *
+ * This module implements a general bitmap allocator/deallocator. The
+ * allocator eats around 2 bits per 'block'. The module does not
+ * try to interpret the meaning of a 'block' other then to return
+ * SWAPBLK_NONE on an allocation failure.
+ *
+ * A radix tree is used to maintain the bitmap. Two radix constants are
+ * involved: One for the bitmaps contained in the leaf nodes (typically
+ * 32), and one for the meta nodes (typically 16). Both meta and leaf
+ * nodes have a hint field. This field gives us a hint as to the largest
+ * free contiguous range of blocks under the node. It may contain a
+ * value that is too high, but will never contain a value that is too
+ * low. When the radix tree is searched, allocation failures in subtrees
+ * update the hint.
+ *
+ * The radix tree also implements two collapsed states for meta nodes:
+ * the ALL-ALLOCATED state and the ALL-FREE state. If a meta node is
+ * in either of these two states, all information contained underneath
+ * the node is considered stale. These states are used to optimize
+ * allocation and freeing operations.
+ *
+ * The hinting greatly increases code efficiency for allocations while
+ * the general radix structure optimizes both allocations and frees. The
+ * radix tree should be able to operate well no matter how much
+ * fragmentation there is and no matter how large a bitmap is used.
+ *
+ * Unlike the rlist code, the blist code wires all necessary memory at
+ * creation time. Neither allocations nor frees require interaction with
+ * the memory subsystem. In contrast, the rlist code may allocate memory
+ * on an rlist_free() call. The non-blocking features of the blist code
+ * are used to great advantage in the swap code (vm/nswap_pager.c). The
+ * rlist code uses a little less overall memory then the blist code (but
+ * due to swap interleaving not all that much less), but the blist code
+ * scales much, much better.
+ *
+ * LAYOUT: The radix tree is layed out recursively using a
+ * linear array. Each meta node is immediately followed (layed out
+ * sequentially in memory) by BLIST_META_RADIX lower level nodes. This
+ * is a recursive structure but one that can be easily scanned through
+ * a very simple 'skip' calculation. In order to support large radixes,
+ * portions of the tree may reside outside our memory allocation. We
+ * handle this with an early-termination optimization (when bighint is
+ * set to -1) on the scan. The memory allocation is only large enough
+ * to cover the number of blocks requested at creation time even if it
+ * must be encompassed in larger root-node radix.
+ *
+ * NOTE: the allocator cannot currently allocate more then
+ * BLIST_BMAP_RADIX blocks per call. It will panic with 'allocation too
+ * large' if you try. This is an area that could use improvement. The
+ * radix is large enough that this restriction does not effect the swap
+ * system, though. Currently only the allocation code is effected by
+ * this algorithmic unfeature. The freeing code can handle arbitrary
+ * ranges.
+ *
+ * This code can be compiled stand-alone for debugging.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD: src/sys/kern/subr_blist.c,v 1.17 2004/06/04 04:03:25 alc Exp $");
+
+#ifdef _KERNEL
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/lock.h>
+#include <sys/kernel.h>
+#include <sys/blist.h>
+#include <sys/malloc.h>
+#include <sys/proc.h>
+#include <sys/mutex.h>
+
+#else
+
+#ifndef BLIST_NO_DEBUG
+#define BLIST_DEBUG
+#endif
+
+#define SWAPBLK_NONE ((daddr_t)-1)
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdarg.h>
+
+#define malloc(a,b,c) calloc(a, 1)
+#define free(a,b) free(a)
+
+typedef unsigned int u_daddr_t;
+
+#include <sys/blist.h>
+
+void panic(const char *ctl, ...);
+
+#endif
+
+/*
+ * static support functions
+ */
+
+static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count);
+static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t blk,
+ daddr_t count, daddr_t radix, int skip);
+static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count);
+static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count,
+ daddr_t radix, int skip, daddr_t blk);
+static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix,
+ daddr_t skip, blist_t dest, daddr_t count);
+static int blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count);
+static int blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count,
+ daddr_t radix, int skip, daddr_t blk);
+static daddr_t blst_radix_init(blmeta_t *scan, daddr_t radix,
+ int skip, daddr_t count);
+#ifndef _KERNEL
+static void blst_radix_print(blmeta_t *scan, daddr_t blk,
+ daddr_t radix, int skip, int tab);
+#endif
+
+#ifdef _KERNEL
+static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
+#endif
+
+/*
+ * blist_create() - create a blist capable of handling up to the specified
+ * number of blocks
+ *
+ * blocks must be greater then 0
+ *
+ * The smallest blist consists of a single leaf node capable of
+ * managing BLIST_BMAP_RADIX blocks.
+ */
+
+blist_t
+blist_create(daddr_t blocks)
+{
+ blist_t bl;
+ int radix;
+ int skip = 0;
+
+ /*
+ * Calculate radix and skip field used for scanning.
+ */
+ radix = BLIST_BMAP_RADIX;
+
+ while (radix < blocks) {
+ radix *= BLIST_META_RADIX;
+ skip = (skip + 1) * BLIST_META_RADIX;
+ }
+
+ bl = malloc(sizeof(struct blist), M_SWAP, M_WAITOK | M_ZERO);
+
+ bl->bl_blocks = blocks;
+ bl->bl_radix = radix;
+ bl->bl_skip = skip;
+ bl->bl_rootblks = 1 +
+ blst_radix_init(NULL, bl->bl_radix, bl->bl_skip, blocks);
+ bl->bl_root = malloc(sizeof(blmeta_t) * bl->bl_rootblks, M_SWAP, M_WAITOK);
+
+#if defined(BLIST_DEBUG)
+ printf(
+ "BLIST representing %lld blocks (%lld MB of swap)"
+ ", requiring %lldK of ram\n",
+ (long long)bl->bl_blocks,
+ (long long)bl->bl_blocks * 4 / 1024,
+ (long long)(bl->bl_rootblks * sizeof(blmeta_t) + 1023) / 1024
+ );
+ printf("BLIST raw radix tree contains %lld records\n",
+ (long long)bl->bl_rootblks);
+#endif
+ blst_radix_init(bl->bl_root, bl->bl_radix, bl->bl_skip, blocks);
+
+ return(bl);
+}
+
+void
+blist_destroy(blist_t bl)
+{
+ free(bl->bl_root, M_SWAP);
+ free(bl, M_SWAP);
+}
+
+/*
+ * blist_alloc() - reserve space in the block bitmap. Return the base
+ * of a contiguous region or SWAPBLK_NONE if space could
+ * not be allocated.
+ */
+
+daddr_t
+blist_alloc(blist_t bl, daddr_t count)
+{
+ daddr_t blk = SWAPBLK_NONE;
+
+ if (bl) {
+ if (bl->bl_radix == BLIST_BMAP_RADIX)
+ blk = blst_leaf_alloc(bl->bl_root, 0, count);
+ else
+ blk = blst_meta_alloc(bl->bl_root, 0, count, bl->bl_radix, bl->bl_skip);
+ if (blk != SWAPBLK_NONE)
+ bl->bl_free -= count;
+ }
+ return(blk);
+}
+
+/*
+ * blist_free() - free up space in the block bitmap. Return the base
+ * of a contiguous region. Panic if an inconsistancy is
+ * found.
+ */
+
+void
+blist_free(blist_t bl, daddr_t blkno, daddr_t count)
+{
+ if (bl) {
+ if (bl->bl_radix == BLIST_BMAP_RADIX)
+ blst_leaf_free(bl->bl_root, blkno, count);
+ else
+ blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix, bl->bl_skip, 0);
+ bl->bl_free += count;
+ }
+}
+
+/*
+ * blist_fill() - mark a region in the block bitmap as off-limits
+ * to the allocator (i.e. allocate it), ignoring any
+ * existing allocations. Return the number of blocks
+ * actually filled that were free before the call.
+ */
+
+int
+blist_fill(blist_t bl, daddr_t blkno, daddr_t count)
+{
+ int filled;
+
+ if (bl) {
+ if (bl->bl_radix == BLIST_BMAP_RADIX)
+ filled = blst_leaf_fill(bl->bl_root, blkno, count);
+ else
+ filled = blst_meta_fill(bl->bl_root, blkno, count,
+ bl->bl_radix, bl->bl_skip, 0);
+ bl->bl_free -= filled;
+ return filled;
+ } else
+ return 0;
+}
+
+/*
+ * blist_resize() - resize an existing radix tree to handle the
+ * specified number of blocks. This will reallocate
+ * the tree and transfer the previous bitmap to the new
+ * one. When extending the tree you can specify whether
+ * the new blocks are to left allocated or freed.
+ */
+
+void
+blist_resize(blist_t *pbl, daddr_t count, int freenew)
+{
+ blist_t newbl = blist_create(count);
+ blist_t save = *pbl;
+
+ *pbl = newbl;
+ if (count > save->bl_blocks)
+ count = save->bl_blocks;
+ blst_copy(save->bl_root, 0, save->bl_radix, save->bl_skip, newbl, count);
+
+ /*
+ * If resizing upwards, should we free the new space or not?
+ */
+ if (freenew && count < newbl->bl_blocks) {
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