1/*
2 * Copyright (c) 2002, Jeffrey Roberson <jroberson@chesapeake.net>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
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18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/vm/uma_int.h 93818 2002-04-04 21:03:38Z jhb $
27 *
28 */
29
30/*
31 *
32 * Jeff Roberson <jroberson@chesapeake.net>
33 *
34 * This file includes definitions, structures, prototypes, and inlines that
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47 * for pages that don't have embedded uma_slab_t's.
48 *
49 * The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may
50 * be allocated off the page from a special slab zone. The free list within a
51 * slab is managed with a linked list of indexes, which are 8 bit values. If
52 * UMA_SLAB_SIZE is defined to be too large I will have to switch to 16bit
53 * values. Currently on alpha you can get 250 or so 32 byte items and on x86
54 * you can get 250 or so 16byte items. For item sizes that would yield more
55 * than 10% memory waste we potentially allocate a seperate uma_slab_t if this
56 * will improve the number of items per slab that will fit.
57 *
58 * Other potential space optimizations are storing the 8bit of linkage in space
59 * wasted between items due to alignment problems. This may yield a much better
60 * memory footprint for certain sizes of objects. Another alternative is to
61 * increase the UMA_SLAB_SIZE, or allow for dynamic slab sizes. I prefer
62 * dynamic slab sizes because we could stick with 8 bit indexes and only use
63 * large slab sizes for zones with a lot of waste per slab. This may create
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2 * Copyright (c) 2002, Jeffrey Roberson <jroberson@chesapeake.net>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
--- 9 unchanged lines hidden (view full) ---
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/vm/uma_int.h 93818 2002-04-04 21:03:38Z jhb $
27 *
28 */
29
30/*
31 *
32 * Jeff Roberson <jroberson@chesapeake.net>
33 *
34 * This file includes definitions, structures, prototypes, and inlines that
--- 12 unchanged lines hidden (view full) ---
47 * for pages that don't have embedded uma_slab_t's.
48 *
49 * The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may
50 * be allocated off the page from a special slab zone. The free list within a
51 * slab is managed with a linked list of indexes, which are 8 bit values. If
52 * UMA_SLAB_SIZE is defined to be too large I will have to switch to 16bit
53 * values. Currently on alpha you can get 250 or so 32 byte items and on x86
54 * you can get 250 or so 16byte items. For item sizes that would yield more
55 * than 10% memory waste we potentially allocate a seperate uma_slab_t if this
56 * will improve the number of items per slab that will fit.
57 *
58 * Other potential space optimizations are storing the 8bit of linkage in space
59 * wasted between items due to alignment problems. This may yield a much better
60 * memory footprint for certain sizes of objects. Another alternative is to
61 * increase the UMA_SLAB_SIZE, or allow for dynamic slab sizes. I prefer
62 * dynamic slab sizes because we could stick with 8 bit indexes and only use
63 * large slab sizes for zones with a lot of waste per slab. This may create
--- 267 unchanged lines hidden ---