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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /drivers/gpu/drm/i915/i915_syncmap.c | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'drivers/gpu/drm/i915/i915_syncmap.c')
-rw-r--r-- | drivers/gpu/drm/i915/i915_syncmap.c | 412 |
1 files changed, 412 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_syncmap.c b/drivers/gpu/drm/i915/i915_syncmap.c new file mode 100644 index 0000000000..60404dbb2e --- /dev/null +++ b/drivers/gpu/drm/i915/i915_syncmap.c @@ -0,0 +1,412 @@ +/* + * Copyright © 2017 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + * + */ + +#include <linux/slab.h> + +#include "i915_syncmap.h" + +#include "i915_gem.h" /* GEM_BUG_ON() */ +#include "i915_selftest.h" + +#define SHIFT ilog2(KSYNCMAP) +#define MASK (KSYNCMAP - 1) + +/* + * struct i915_syncmap is a layer of a radixtree that maps a u64 fence + * context id to the last u32 fence seqno waited upon from that context. + * Unlike lib/radixtree it uses a parent pointer that allows traversal back to + * the root. This allows us to access the whole tree via a single pointer + * to the most recently used layer. We expect fence contexts to be dense + * and most reuse to be on the same i915_gem_context but on neighbouring + * engines (i.e. on adjacent contexts) and reuse the same leaf, a very + * effective lookup cache. If the new lookup is not on the same leaf, we + * expect it to be on the neighbouring branch. + * + * A leaf holds an array of u32 seqno, and has height 0. The bitmap field + * allows us to store whether a particular seqno is valid (i.e. allows us + * to distinguish unset from 0). + * + * A branch holds an array of layer pointers, and has height > 0, and always + * has at least 2 layers (either branches or leaves) below it. + * + * For example, + * for x in + * 0 1 2 0x10 0x11 0x200 0x201 + * 0x500000 0x500001 0x503000 0x503001 + * 0xE<<60: + * i915_syncmap_set(&sync, x, lower_32_bits(x)); + * will build a tree like: + * 0xXXXXXXXXXXXXXXXX + * 0-> 0x0000000000XXXXXX + * | 0-> 0x0000000000000XXX + * | | 0-> 0x00000000000000XX + * | | | 0-> 0x000000000000000X 0:0, 1:1, 2:2 + * | | | 1-> 0x000000000000001X 0:10, 1:11 + * | | 2-> 0x000000000000020X 0:200, 1:201 + * | 5-> 0x000000000050XXXX + * | 0-> 0x000000000050000X 0:500000, 1:500001 + * | 3-> 0x000000000050300X 0:503000, 1:503001 + * e-> 0xe00000000000000X e:e + */ + +struct i915_syncmap { + u64 prefix; + unsigned int height; + unsigned int bitmap; + struct i915_syncmap *parent; + /* + * Following this header is an array of either seqno or child pointers: + * union { + * u32 seqno[KSYNCMAP]; + * struct i915_syncmap *child[KSYNCMAP]; + * }; + */ +}; + +/** + * i915_syncmap_init -- initialise the #i915_syncmap + * @root: pointer to the #i915_syncmap + */ +void i915_syncmap_init(struct i915_syncmap **root) +{ + BUILD_BUG_ON_NOT_POWER_OF_2(KSYNCMAP); + BUILD_BUG_ON_NOT_POWER_OF_2(SHIFT); + BUILD_BUG_ON(KSYNCMAP > BITS_PER_TYPE((*root)->bitmap)); + *root = NULL; +} + +static inline u32 *__sync_seqno(struct i915_syncmap *p) +{ + GEM_BUG_ON(p->height); + return (u32 *)(p + 1); +} + +static inline struct i915_syncmap **__sync_child(struct i915_syncmap *p) +{ + GEM_BUG_ON(!p->height); + return (struct i915_syncmap **)(p + 1); +} + +static inline unsigned int +__sync_branch_idx(const struct i915_syncmap *p, u64 id) +{ + return (id >> p->height) & MASK; +} + +static inline unsigned int +__sync_leaf_idx(const struct i915_syncmap *p, u64 id) +{ + GEM_BUG_ON(p->height); + return id & MASK; +} + +static inline u64 __sync_branch_prefix(const struct i915_syncmap *p, u64 id) +{ + return id >> p->height >> SHIFT; +} + +static inline u64 __sync_leaf_prefix(const struct i915_syncmap *p, u64 id) +{ + GEM_BUG_ON(p->height); + return id >> SHIFT; +} + +static inline bool seqno_later(u32 a, u32 b) +{ + return (s32)(a - b) >= 0; +} + +/** + * i915_syncmap_is_later -- compare against the last know sync point + * @root: pointer to the #i915_syncmap + * @id: the context id (other timeline) we are synchronising to + * @seqno: the sequence number along the other timeline + * + * If we have already synchronised this @root timeline with another (@id) then + * we can omit any repeated or earlier synchronisation requests. If the two + * timelines are already coupled, we can also omit the dependency between the + * two as that is already known via the timeline. + * + * Returns true if the two timelines are already synchronised wrt to @seqno, + * false if not and the synchronisation must be emitted. + */ +bool i915_syncmap_is_later(struct i915_syncmap **root, u64 id, u32 seqno) +{ + struct i915_syncmap *p; + unsigned int idx; + + p = *root; + if (!p) + return false; + + if (likely(__sync_leaf_prefix(p, id) == p->prefix)) + goto found; + + /* First climb the tree back to a parent branch */ + do { + p = p->parent; + if (!p) + return false; + + if (__sync_branch_prefix(p, id) == p->prefix) + break; + } while (1); + + /* And then descend again until we find our leaf */ + do { + if (!p->height) + break; + + p = __sync_child(p)[__sync_branch_idx(p, id)]; + if (!p) + return false; + + if (__sync_branch_prefix(p, id) != p->prefix) + return false; + } while (1); + + *root = p; +found: + idx = __sync_leaf_idx(p, id); + if (!(p->bitmap & BIT(idx))) + return false; + + return seqno_later(__sync_seqno(p)[idx], seqno); +} + +static struct i915_syncmap * +__sync_alloc_leaf(struct i915_syncmap *parent, u64 id) +{ + struct i915_syncmap *p; + + p = kmalloc(sizeof(*p) + KSYNCMAP * sizeof(u32), GFP_KERNEL); + if (unlikely(!p)) + return NULL; + + p->parent = parent; + p->height = 0; + p->bitmap = 0; + p->prefix = __sync_leaf_prefix(p, id); + return p; +} + +static inline void __sync_set_seqno(struct i915_syncmap *p, u64 id, u32 seqno) +{ + unsigned int idx = __sync_leaf_idx(p, id); + + p->bitmap |= BIT(idx); + __sync_seqno(p)[idx] = seqno; +} + +static inline void __sync_set_child(struct i915_syncmap *p, + unsigned int idx, + struct i915_syncmap *child) +{ + p->bitmap |= BIT(idx); + __sync_child(p)[idx] = child; +} + +static noinline int __sync_set(struct i915_syncmap **root, u64 id, u32 seqno) +{ + struct i915_syncmap *p = *root; + unsigned int idx; + + if (!p) { + p = __sync_alloc_leaf(NULL, id); + if (unlikely(!p)) + return -ENOMEM; + + goto found; + } + + /* Caller handled the likely cached case */ + GEM_BUG_ON(__sync_leaf_prefix(p, id) == p->prefix); + + /* Climb back up the tree until we find a common prefix */ + do { + if (!p->parent) + break; + + p = p->parent; + + if (__sync_branch_prefix(p, id) == p->prefix) + break; + } while (1); + + /* + * No shortcut, we have to descend the tree to find the right layer + * containing this fence. + * + * Each layer in the tree holds 16 (KSYNCMAP) pointers, either fences + * or lower layers. Leaf nodes (height = 0) contain the fences, all + * other nodes (height > 0) are internal layers that point to a lower + * node. Each internal layer has at least 2 descendents. + * + * Starting at the top, we check whether the current prefix matches. If + * it doesn't, we have gone past our target and need to insert a join + * into the tree, and a new leaf node for the target as a descendent + * of the join, as well as the original layer. + * + * The matching prefix means we are still following the right branch + * of the tree. If it has height 0, we have found our leaf and just + * need to replace the fence slot with ourselves. If the height is + * not zero, our slot contains the next layer in the tree (unless + * it is empty, in which case we can add ourselves as a new leaf). + * As descend the tree the prefix grows (and height decreases). + */ + do { + struct i915_syncmap *next; + + if (__sync_branch_prefix(p, id) != p->prefix) { + unsigned int above; + + /* Insert a join above the current layer */ + next = kzalloc(sizeof(*next) + KSYNCMAP * sizeof(next), + GFP_KERNEL); + if (unlikely(!next)) + return -ENOMEM; + + /* Compute the height at which these two diverge */ + above = fls64(__sync_branch_prefix(p, id) ^ p->prefix); + above = round_up(above, SHIFT); + next->height = above + p->height; + next->prefix = __sync_branch_prefix(next, id); + + /* Insert the join into the parent */ + if (p->parent) { + idx = __sync_branch_idx(p->parent, id); + __sync_child(p->parent)[idx] = next; + GEM_BUG_ON(!(p->parent->bitmap & BIT(idx))); + } + next->parent = p->parent; + + /* Compute the idx of the other branch, not our id! */ + idx = p->prefix >> (above - SHIFT) & MASK; + __sync_set_child(next, idx, p); + p->parent = next; + + /* Ascend to the join */ + p = next; + } else { + if (!p->height) + break; + } + + /* Descend into the next layer */ + GEM_BUG_ON(!p->height); + idx = __sync_branch_idx(p, id); + next = __sync_child(p)[idx]; + if (!next) { + next = __sync_alloc_leaf(p, id); + if (unlikely(!next)) + return -ENOMEM; + + __sync_set_child(p, idx, next); + p = next; + break; + } + + p = next; + } while (1); + +found: + GEM_BUG_ON(p->prefix != __sync_leaf_prefix(p, id)); + __sync_set_seqno(p, id, seqno); + *root = p; + return 0; +} + +/** + * i915_syncmap_set -- mark the most recent syncpoint between contexts + * @root: pointer to the #i915_syncmap + * @id: the context id (other timeline) we have synchronised to + * @seqno: the sequence number along the other timeline + * + * When we synchronise this @root timeline with another (@id), we also know + * that we have synchronized with all previous seqno along that timeline. If + * we then have a request to synchronise with the same seqno or older, we can + * omit it, see i915_syncmap_is_later() + * + * Returns 0 on success, or a negative error code. + */ +int i915_syncmap_set(struct i915_syncmap **root, u64 id, u32 seqno) +{ + struct i915_syncmap *p = *root; + + /* + * We expect to be called in sequence following is_later(id), which + * should have preloaded the root for us. + */ + if (likely(p && __sync_leaf_prefix(p, id) == p->prefix)) { + __sync_set_seqno(p, id, seqno); + return 0; + } + + return __sync_set(root, id, seqno); +} + +static void __sync_free(struct i915_syncmap *p) +{ + if (p->height) { + unsigned int i; + + while ((i = ffs(p->bitmap))) { + p->bitmap &= ~0u << i; + __sync_free(__sync_child(p)[i - 1]); + } + } + + kfree(p); +} + +/** + * i915_syncmap_free -- free all memory associated with the syncmap + * @root: pointer to the #i915_syncmap + * + * Either when the timeline is to be freed and we no longer need the sync + * point tracking, or when the fences are all known to be signaled and the + * sync point tracking is redundant, we can free the #i915_syncmap to recover + * its allocations. + * + * Will reinitialise the @root pointer so that the #i915_syncmap is ready for + * reuse. + */ +void i915_syncmap_free(struct i915_syncmap **root) +{ + struct i915_syncmap *p; + + p = *root; + if (!p) + return; + + while (p->parent) + p = p->parent; + + __sync_free(p); + *root = NULL; +} + +#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST) +#include "selftests/i915_syncmap.c" +#endif |