2 * Copyright (c) 2020 Collabora, Ltd.
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * Authors (Collabora):
24 * Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
27 /* Index buffer min/max cache. We need to calculate the min/max for arbitrary
28 * slices (start, start + count) of the index buffer at drawtime. As this can
29 * be quite expensive, we cache. Conceptually, we just use a hash table mapping
30 * the key (start, count) to the value (min, max). In practice, mesa's hash
31 * table implementation is higher overhead than we would like and makes
32 * handling memory usage a little complicated. So we use this data structure
33 * instead. Searching is O(n) to the size, but the size is capped at the
34 * PANFROST_MINMAX_SIZE constant (so this is a tradeoff between cache hit/miss
35 * ratio and cache search speed). Note that keys are adjacent so we get cache
36 * line alignment benefits. Insertion is O(1) and in-order until the cache
37 * fills up, after that it evicts the oldest cached value in a ring facilitated
41 #include "pan_minmax_cache.h"
44 panfrost_minmax_cache_get(struct panfrost_minmax_cache
*cache
, unsigned start
, unsigned count
,
45 unsigned *min_index
, unsigned *max_index
)
47 uint64_t ht_key
= (((uint64_t)count
) << 32) | start
;
53 for (unsigned i
= 0; i
< cache
->size
; ++i
) {
54 if (cache
->keys
[i
] == ht_key
) {
55 uint64_t hit
= cache
->values
[i
];
57 *min_index
= hit
& 0xffffffff;
58 *max_index
= hit
>> 32;
68 panfrost_minmax_cache_add(struct panfrost_minmax_cache
*cache
, unsigned start
, unsigned count
,
69 unsigned min_index
, unsigned max_index
)
71 uint64_t ht_key
= (((uint64_t)count
) << 32) | start
;
72 uint64_t value
= min_index
| (((uint64_t)max_index
) << 32);
78 if (cache
->size
== PANFROST_MINMAX_SIZE
) {
79 index
= cache
->index
++;
80 cache
->index
= cache
->index
% PANFROST_MINMAX_SIZE
;
82 index
= cache
->size
++;
85 cache
->keys
[index
] = ht_key
;
86 cache
->values
[index
] = value
;
90 /* If we've been caching min/max indices and we update the index
91 * buffer, that may invalidate the min/max. Check what's been cached vs
92 * what we've written, and throw out invalid entries. */
95 panfrost_minmax_cache_invalidate(struct panfrost_minmax_cache
*cache
, struct pipe_transfer
*transfer
)
97 /* Ensure there is a cache to invalidate and a write */
101 if (!(transfer
->usage
& PIPE_TRANSFER_WRITE
))
104 unsigned valid_count
= 0;
106 for (unsigned i
= 0; i
< cache
->size
; ++i
) {
107 uint64_t key
= cache
->keys
[i
];
109 uint32_t start
= key
& 0xffffffff;
110 uint32_t count
= key
>> 32;
112 /* 1D range intersection */
113 bool invalid
= MAX2(transfer
->box
.x
, start
) < MIN2(transfer
->box
.x
+ transfer
->box
.width
, start
+ count
);
115 cache
->keys
[valid_count
] = key
;
116 cache
->values
[valid_count
] = cache
->values
[i
];
121 cache
->size
= valid_count
;