diff options
Diffstat (limited to 'drivers/gpu/nvgpu/gk20a/lockless_allocator_priv.h')
-rw-r--r-- | drivers/gpu/nvgpu/gk20a/lockless_allocator_priv.h | 121 |
1 files changed, 0 insertions, 121 deletions
diff --git a/drivers/gpu/nvgpu/gk20a/lockless_allocator_priv.h b/drivers/gpu/nvgpu/gk20a/lockless_allocator_priv.h deleted file mode 100644 index f9b03e0e..00000000 --- a/drivers/gpu/nvgpu/gk20a/lockless_allocator_priv.h +++ /dev/null | |||
@@ -1,121 +0,0 @@ | |||
1 | /* | ||
2 | * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved. | ||
3 | * | ||
4 | * This program is free software; you can redistribute it and/or modify it | ||
5 | * under the terms and conditions of the GNU General Public License, | ||
6 | * version 2, as published by the Free Software Foundation. | ||
7 | * | ||
8 | * This program is distributed in the hope it will be useful, but WITHOUT | ||
9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | ||
11 | * more details. | ||
12 | * | ||
13 | * You should have received a copy of the GNU General Public License | ||
14 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
15 | */ | ||
16 | |||
17 | /* | ||
18 | * Basics: | ||
19 | * | ||
20 | * - Lockless memory allocator for fixed-size structures, whose | ||
21 | * size is defined up front at init time. | ||
22 | * - Memory footprint scales linearly w/ the number of structures in | ||
23 | * the pool. It is ~= sizeof(int) * N. | ||
24 | * - Memory is pre-allocated by the client. The allocator itself | ||
25 | * only computes the addresses for allocations. | ||
26 | * - Limit of MAX_INT nodes that the allocator can be responsible for. | ||
27 | * | ||
28 | * Implementation details: | ||
29 | * | ||
30 | * The allocator maintains a single list of free nodes. We allocate & | ||
31 | * free nodes from the head of the list. We rely on the cmpxchg() operator | ||
32 | * to maintain atomicity on the head. | ||
33 | * | ||
34 | * So, both allocs & frees are O(1)!! | ||
35 | * | ||
36 | * -- Definitions -- | ||
37 | * Block Size - size of a single structure that this allocator will | ||
38 | * allocate. | ||
39 | * Node - one of the elements of size blk_size in the | ||
40 | * client-allocated buffer. | ||
41 | * Node Index - zero-based index of a node in the client-allocated | ||
42 | * contiguous buffer. | ||
43 | * | ||
44 | * -- Initial State -- | ||
45 | * We maintain the following to track the state of the free list: | ||
46 | * | ||
47 | * 1) A "head" index to track the index of the first free node in the list | ||
48 | * 2) A "next" array to track the index of the next free node in the list | ||
49 | * for every node. So next[head], will give the index to the 2nd free | ||
50 | * element in the list. | ||
51 | * | ||
52 | * So, to begin with, the free list consists of all node indices, and each | ||
53 | * position in the next array contains index N + 1: | ||
54 | * | ||
55 | * head = 0 | ||
56 | * next = [1, 2, 3, 4, -1] : Example for a user-allocated buffer of 5 nodes | ||
57 | * free_list = 0->1->2->3->4->-1 | ||
58 | * | ||
59 | * -- Allocations -- | ||
60 | * 1) Read the current head (aka acq_head) | ||
61 | * 2) Read next[acq_head], to get the 2nd free element (aka new_head) | ||
62 | * 3) cmp_xchg(&head, acq_head, new_head) | ||
63 | * 4) If it succeeds, compute the address of the node, based on | ||
64 | * base address, blk_size, & acq_head. | ||
65 | * | ||
66 | * head = 1; | ||
67 | * next = [1, 2, 3, 4, -1] : Example after allocating Node #0 | ||
68 | * free_list = 1->2->3->4->-1 | ||
69 | * | ||
70 | * head = 2; | ||
71 | * next = [1, 2, 3, 4, -1] : Example after allocating Node #1 | ||
72 | * free_list = 2->3->4->-1 | ||
73 | * | ||
74 | * -- Frees -- | ||
75 | * 1) Based on the address to be freed, calculate the index of the node | ||
76 | * being freed (cur_idx) | ||
77 | * 2) Read the current head (old_head) | ||
78 | * 3) So the freed node is going to go at the head of the list, and we | ||
79 | * want to put the old_head after it. So next[cur_idx] = old_head | ||
80 | * 4) cmpxchg(head, old_head, cur_idx) | ||
81 | * | ||
82 | * head = 0 | ||
83 | * next = [2, 2, 3, 4, -1] | ||
84 | * free_list = 0->2->3->4->-1 : Example after freeing Node #0 | ||
85 | * | ||
86 | * head = 1 | ||
87 | * next = [2, 0, 3, 4, -1] | ||
88 | * free_list = 1->0->2->3->4->-1 : Example after freeing Node #1 | ||
89 | */ | ||
90 | |||
91 | #ifndef LOCKLESS_ALLOCATOR_PRIV_H | ||
92 | #define LOCKLESS_ALLOCATOR_PRIV_H | ||
93 | |||
94 | struct gk20a_allocator; | ||
95 | |||
96 | struct gk20a_lockless_allocator { | ||
97 | struct gk20a_allocator *owner; | ||
98 | |||
99 | u64 base; /* Base address of the space. */ | ||
100 | u64 length; /* Length of the space. */ | ||
101 | u64 blk_size; /* Size of the structure being allocated */ | ||
102 | int nr_nodes; /* Number of nodes available for allocation */ | ||
103 | |||
104 | int *next; /* An array holding the next indices per node */ | ||
105 | int head; /* Current node at the top of the stack */ | ||
106 | |||
107 | u64 flags; | ||
108 | |||
109 | bool inited; | ||
110 | |||
111 | /* Statistics */ | ||
112 | atomic_t nr_allocs; | ||
113 | }; | ||
114 | |||
115 | static inline struct gk20a_lockless_allocator *lockless_allocator( | ||
116 | struct gk20a_allocator *a) | ||
117 | { | ||
118 | return (struct gk20a_lockless_allocator *)(a)->priv; | ||
119 | } | ||
120 | |||
121 | #endif | ||