[Intel-gfx] [PATCH 02/24] drm/i915: Revert relocation chaining commits.
Daniel Vetter
daniel at ffwll.ch
Tue Aug 11 12:41:57 UTC 2020
On Mon, Aug 10, 2020 at 12:30:41PM +0200, Maarten Lankhorst wrote:
> This reverts commit 964a9b0f611ee ("drm/i915/gem: Use chained reloc batches")
> and commit 0e97fbb080553 ("drm/i915/gem: Use a single chained reloc batches
> for a single execbuf").
>
> When adding ww locking to execbuf, it's hard enough to deal with a
> single BO that is part of relocation execution. Chaining is hard to
> get right, and with GPU relocation deprecated, it's best to drop this
> altogether, instead of trying to fix something we will remove.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> ---
> .../gpu/drm/i915/gem/i915_gem_execbuffer.c | 171 ++++--------------
> .../i915/gem/selftests/i915_gem_execbuffer.c | 8 +-
> 2 files changed, 35 insertions(+), 144 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index c6a613d92a13..6acbd08f82f0 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -276,9 +276,7 @@ struct i915_execbuffer {
> bool has_fence : 1;
> bool needs_unfenced : 1;
>
> - struct i915_vma *target;
> struct i915_request *rq;
> - struct i915_vma *rq_vma;
> u32 *rq_cmd;
> unsigned int rq_size;
> } reloc_cache;
> @@ -973,7 +971,7 @@ static void reloc_cache_init(struct reloc_cache *cache,
> cache->needs_unfenced = INTEL_INFO(i915)->unfenced_needs_alignment;
> cache->node.flags = 0;
> cache->rq = NULL;
> - cache->target = NULL;
> + cache->rq_size = 0;
This hunk is from e3d291301f99 ("drm/i915/gem: Implement legacy
MI_STORE_DATA_IMM") and reverted here, needed to not totally break the
selftest. Which this patch also updates aside from just the 2 reverts.
Otherwise this seems to match the reconstruted revert I've done here.
Please mention that in the commit message, with that:
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> }
>
> static inline void *unmask_page(unsigned long p)
> @@ -995,122 +993,29 @@ static inline struct i915_ggtt *cache_to_ggtt(struct reloc_cache *cache)
> return &i915->ggtt;
> }
>
> -#define RELOC_TAIL 4
> -
> -static int reloc_gpu_chain(struct reloc_cache *cache)
> +static void reloc_gpu_flush(struct reloc_cache *cache)
> {
> - struct intel_gt_buffer_pool_node *pool;
> - struct i915_request *rq = cache->rq;
> - struct i915_vma *batch;
> - u32 *cmd;
> - int err;
> -
> - pool = intel_gt_get_buffer_pool(rq->engine->gt, PAGE_SIZE);
> - if (IS_ERR(pool))
> - return PTR_ERR(pool);
> -
> - batch = i915_vma_instance(pool->obj, rq->context->vm, NULL);
> - if (IS_ERR(batch)) {
> - err = PTR_ERR(batch);
> - goto out_pool;
> - }
> -
> - err = i915_vma_pin(batch, 0, 0, PIN_USER | PIN_NONBLOCK);
> - if (err)
> - goto out_pool;
> -
> - GEM_BUG_ON(cache->rq_size + RELOC_TAIL > PAGE_SIZE / sizeof(u32));
> - cmd = cache->rq_cmd + cache->rq_size;
> - *cmd++ = MI_ARB_CHECK;
> - if (cache->gen >= 8)
> - *cmd++ = MI_BATCH_BUFFER_START_GEN8;
> - else if (cache->gen >= 6)
> - *cmd++ = MI_BATCH_BUFFER_START;
> - else
> - *cmd++ = MI_BATCH_BUFFER_START | MI_BATCH_GTT;
> - *cmd++ = lower_32_bits(batch->node.start);
> - *cmd++ = upper_32_bits(batch->node.start); /* Always 0 for gen<8 */
> - i915_gem_object_flush_map(cache->rq_vma->obj);
> - i915_gem_object_unpin_map(cache->rq_vma->obj);
> - cache->rq_vma = NULL;
> -
> - err = intel_gt_buffer_pool_mark_active(pool, rq);
> - if (err == 0) {
> - i915_vma_lock(batch);
> - err = i915_request_await_object(rq, batch->obj, false);
> - if (err == 0)
> - err = i915_vma_move_to_active(batch, rq, 0);
> - i915_vma_unlock(batch);
> - }
> - i915_vma_unpin(batch);
> - if (err)
> - goto out_pool;
> + struct drm_i915_gem_object *obj = cache->rq->batch->obj;
>
> - cmd = i915_gem_object_pin_map(batch->obj,
> - cache->has_llc ?
> - I915_MAP_FORCE_WB :
> - I915_MAP_FORCE_WC);
> - if (IS_ERR(cmd)) {
> - err = PTR_ERR(cmd);
> - goto out_pool;
> - }
> + GEM_BUG_ON(cache->rq_size >= obj->base.size / sizeof(u32));
> + cache->rq_cmd[cache->rq_size] = MI_BATCH_BUFFER_END;
>
> - /* Return with batch mapping (cmd) still pinned */
> - cache->rq_cmd = cmd;
> - cache->rq_size = 0;
> - cache->rq_vma = batch;
> + __i915_gem_object_flush_map(obj, 0, sizeof(u32) * (cache->rq_size + 1));
> + i915_gem_object_unpin_map(obj);
>
> -out_pool:
> - intel_gt_buffer_pool_put(pool);
> - return err;
> -}
> + intel_gt_chipset_flush(cache->rq->engine->gt);
>
> -static unsigned int reloc_bb_flags(const struct reloc_cache *cache)
> -{
> - return cache->gen > 5 ? 0 : I915_DISPATCH_SECURE;
> -}
> -
> -static int reloc_gpu_flush(struct reloc_cache *cache)
> -{
> - struct i915_request *rq;
> - int err;
> -
> - rq = fetch_and_zero(&cache->rq);
> - if (!rq)
> - return 0;
> -
> - if (cache->rq_vma) {
> - struct drm_i915_gem_object *obj = cache->rq_vma->obj;
> -
> - GEM_BUG_ON(cache->rq_size >= obj->base.size / sizeof(u32));
> - cache->rq_cmd[cache->rq_size++] = MI_BATCH_BUFFER_END;
> -
> - __i915_gem_object_flush_map(obj,
> - 0, sizeof(u32) * cache->rq_size);
> - i915_gem_object_unpin_map(obj);
> - }
> -
> - err = 0;
> - if (rq->engine->emit_init_breadcrumb)
> - err = rq->engine->emit_init_breadcrumb(rq);
> - if (!err)
> - err = rq->engine->emit_bb_start(rq,
> - rq->batch->node.start,
> - PAGE_SIZE,
> - reloc_bb_flags(cache));
> - if (err)
> - i915_request_set_error_once(rq, err);
> -
> - intel_gt_chipset_flush(rq->engine->gt);
> - i915_request_add(rq);
> -
> - return err;
> + i915_request_add(cache->rq);
> + cache->rq = NULL;
> }
>
> static void reloc_cache_reset(struct reloc_cache *cache)
> {
> void *vaddr;
>
> + if (cache->rq)
> + reloc_gpu_flush(cache);
> +
> if (!cache->vaddr)
> return;
>
> @@ -1309,6 +1214,7 @@ static int reloc_move_to_gpu(struct i915_request *rq, struct i915_vma *vma)
>
> static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
> struct intel_engine_cs *engine,
> + struct i915_vma *vma,
> unsigned int len)
> {
> struct reloc_cache *cache = &eb->reloc_cache;
> @@ -1331,7 +1237,7 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
> goto out_pool;
> }
>
> - batch = i915_vma_instance(pool->obj, eb->context->vm, NULL);
> + batch = i915_vma_instance(pool->obj, vma->vm, NULL);
> if (IS_ERR(batch)) {
> err = PTR_ERR(batch);
> goto err_unmap;
> @@ -1367,6 +1273,16 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
> if (err)
> goto err_request;
>
> + err = reloc_move_to_gpu(rq, vma);
> + if (err)
> + goto err_request;
> +
> + err = eb->engine->emit_bb_start(rq,
> + batch->node.start, PAGE_SIZE,
> + cache->gen > 5 ? 0 : I915_DISPATCH_SECURE);
> + if (err)
> + goto skip_request;
> +
> i915_vma_lock(batch);
> err = i915_request_await_object(rq, batch->obj, false);
> if (err == 0)
> @@ -1381,7 +1297,6 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
> cache->rq = rq;
> cache->rq_cmd = cmd;
> cache->rq_size = 0;
> - cache->rq_vma = batch;
>
> /* Return with batch mapping (cmd) still pinned */
> goto out_pool;
> @@ -1410,9 +1325,12 @@ static u32 *reloc_gpu(struct i915_execbuffer *eb,
> {
> struct reloc_cache *cache = &eb->reloc_cache;
> u32 *cmd;
> - int err;
> +
> + if (cache->rq_size > PAGE_SIZE/sizeof(u32) - (len + 1))
> + reloc_gpu_flush(cache);
>
> if (unlikely(!cache->rq)) {
> + int err;
> struct intel_engine_cs *engine = eb->engine;
>
> if (!reloc_can_use_engine(engine)) {
> @@ -1421,31 +1339,11 @@ static u32 *reloc_gpu(struct i915_execbuffer *eb,
> return ERR_PTR(-ENODEV);
> }
>
> - err = __reloc_gpu_alloc(eb, engine, len);
> + err = __reloc_gpu_alloc(eb, engine, vma, len);
> if (unlikely(err))
> return ERR_PTR(err);
> }
>
> - if (vma != cache->target) {
> - err = reloc_move_to_gpu(cache->rq, vma);
> - if (unlikely(err)) {
> - i915_request_set_error_once(cache->rq, err);
> - return ERR_PTR(err);
> - }
> -
> - cache->target = vma;
> - }
> -
> - if (unlikely(cache->rq_size + len >
> - PAGE_SIZE / sizeof(u32) - RELOC_TAIL)) {
> - err = reloc_gpu_chain(cache);
> - if (unlikely(err)) {
> - i915_request_set_error_once(cache->rq, err);
> - return ERR_PTR(err);
> - }
> - }
> -
> - GEM_BUG_ON(cache->rq_size + len >= PAGE_SIZE / sizeof(u32));
> cmd = cache->rq_cmd + cache->rq_size;
> cache->rq_size += len;
>
> @@ -1793,20 +1691,15 @@ static int eb_relocate(struct i915_execbuffer *eb)
> /* The objects are in their final locations, apply the relocations. */
> if (eb->args->flags & __EXEC_HAS_RELOC) {
> struct eb_vma *ev;
> - int flush;
>
> list_for_each_entry(ev, &eb->relocs, reloc_link) {
> err = eb_relocate_vma(eb, ev);
> if (err)
> - break;
> + return err;
> }
> -
> - flush = reloc_gpu_flush(&eb->reloc_cache);
> - if (!err)
> - err = flush;
> }
>
> - return err;
> + return 0;
> }
>
> static int eb_move_to_gpu(struct i915_execbuffer *eb)
> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_execbuffer.c
> index a49016f8ee0d..580884cffec3 100644
> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_execbuffer.c
> @@ -53,13 +53,13 @@ static int __igt_gpu_reloc(struct i915_execbuffer *eb,
> }
>
> /* Skip to the end of the cmd page */
> - i = PAGE_SIZE / sizeof(u32) - RELOC_TAIL - 1;
> + i = PAGE_SIZE / sizeof(u32) - 1;
> i -= eb->reloc_cache.rq_size;
> memset32(eb->reloc_cache.rq_cmd + eb->reloc_cache.rq_size,
> MI_NOOP, i);
> eb->reloc_cache.rq_size += i;
>
> - /* Force batch chaining */
> + /* Force next batch */
> if (!__reloc_entry_gpu(eb, vma,
> offsets[2] * sizeof(u32),
> 2)) {
> @@ -69,9 +69,7 @@ static int __igt_gpu_reloc(struct i915_execbuffer *eb,
>
> GEM_BUG_ON(!eb->reloc_cache.rq);
> rq = i915_request_get(eb->reloc_cache.rq);
> - err = reloc_gpu_flush(&eb->reloc_cache);
> - if (err)
> - goto put_rq;
> + reloc_gpu_flush(&eb->reloc_cache);
> GEM_BUG_ON(eb->reloc_cache.rq);
>
> err = i915_gem_object_wait(obj, I915_WAIT_INTERRUPTIBLE, HZ / 2);
> --
> 2.28.0
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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