On 06/07/2020 07:19, Chris Wilson wrote:
In preparation for making eb_vma bigger and heavy to run inn parallel,
in
we need to stop apply an in-place swap() to reorder around ww_mutex
applying
deadlocks. Keep the array intact and reorder the locks using a dedicated
list.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
.../gpu/drm/i915/gem/i915_gem_execbuffer.c | 83 ++++++++++++-------
1 file changed, 54 insertions(+), 29 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 6d20be29ff3c..4d8ac89c56fc 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -37,6 +37,7 @@ struct eb_vma {
struct list_head bind_link;
struct list_head unbound_link;
struct list_head reloc_link;
+ struct list_head submit_link;
struct hlist_node node;
u32 handle;
@@ -248,6 +249,8 @@ struct i915_execbuffer {
/** list of vma that have execobj.relocation_count */
struct list_head relocs;
+ struct list_head submit_list;
+
/**
* Track the most recently used object for relocations, as we
* frequently have to perform multiple relocations within the same
@@ -341,6 +344,42 @@ static void eb_vma_array_put(struct eb_vma_array *arr)
kref_put(&arr->kref, eb_vma_array_destroy);
}
+static int
+eb_lock_vma(struct i915_execbuffer *eb, struct ww_acquire_ctx *acquire)
vmas plural?
+{
+ struct eb_vma *ev;
+ int err = 0;
+
+ list_for_each_entry(ev, &eb->submit_list, submit_link) {
+ struct i915_vma *vma = ev->vma;
+
+ err = ww_mutex_lock_interruptible(&vma->resv->lock, acquire);
+ if (err == -EDEADLK) {
+ struct eb_vma *unlock = ev, *en;
+
+ list_for_each_entry_safe_continue_reverse(unlock, en,
+
&eb->submit_list,
+ submit_link) {
+ ww_mutex_unlock(&unlock->vma->resv->lock);
+ list_move_tail(&unlock->submit_link,
&eb->submit_list);
+ }
+
+ GEM_BUG_ON(!list_is_first(&ev->submit_link,
&eb->submit_list));
+ err = ww_mutex_lock_slow_interruptible(&vma->resv->lock,
+ acquire);
+ }
+ if (err) {
+ list_for_each_entry_continue_reverse(ev,
+ &eb->submit_list,
+ submit_link)
+ ww_mutex_unlock(&ev->vma->resv->lock);
+ break;
+ }
+ }
+
+ return err;
+}
+
static int eb_create(struct i915_execbuffer *eb)
{
/* Allocate an extra slot for use by the command parser + sentinel */
@@ -393,6 +432,10 @@ static int eb_create(struct i915_execbuffer *eb)
eb->lut_size = -eb->buffer_count;
}
+ INIT_LIST_HEAD(&eb->bind_list);
+ INIT_LIST_HEAD(&eb->submit_list);
+ INIT_LIST_HEAD(&eb->relocs);
+
return 0;
}
@@ -574,6 +617,7 @@ eb_add_vma(struct i915_execbuffer *eb,
}
list_add_tail(&ev->bind_link, &eb->bind_list);
+ list_add_tail(&ev->submit_link, &eb->submit_list);
if (entry->relocation_count)
list_add_tail(&ev->reloc_link, &eb->relocs);
@@ -910,9 +954,6 @@ static int eb_lookup_vmas(struct i915_execbuffer *eb)
unsigned int i;
int err = 0;
- INIT_LIST_HEAD(&eb->bind_list);
- INIT_LIST_HEAD(&eb->relocs);
-
for (i = 0; i < eb->buffer_count; i++) {
struct i915_vma *vma;
@@ -1583,38 +1624,19 @@ static int eb_relocate(struct i915_execbuffer *eb)
static int eb_move_to_gpu(struct i915_execbuffer *eb)
{
- const unsigned int count = eb->buffer_count;
struct ww_acquire_ctx acquire;
- unsigned int i;
+ struct eb_vma *ev;
int err = 0;
ww_acquire_init(&acquire, &reservation_ww_class);
- for (i = 0; i < count; i++) {
- struct eb_vma *ev = &eb->vma[i];
- struct i915_vma *vma = ev->vma;
-
- err = ww_mutex_lock_interruptible(&vma->resv->lock, &acquire);
- if (err == -EDEADLK) {
- GEM_BUG_ON(i == 0);
- do {
- int j = i - 1;
-
- ww_mutex_unlock(&eb->vma[j].vma->resv->lock);
-
- swap(eb->vma[i], eb->vma[j]);
- } while (--i);
+ err = eb_lock_vma(eb, &acquire);
+ if (err)
+ goto err_fini;
- err = ww_mutex_lock_slow_interruptible(&vma->resv->lock,
- &acquire);
- }
- if (err)
- break;
- }
ww_acquire_done(&acquire);
- while (i--) {
- struct eb_vma *ev = &eb->vma[i];
+ list_for_each_entry(ev, &eb->submit_list, submit_link) {
struct i915_vma *vma = ev->vma;
unsigned int flags = ev->flags;
struct drm_i915_gem_object *obj = vma->obj;
@@ -1671,6 +1693,8 @@ static int eb_move_to_gpu(struct i915_execbuffer *eb)
intel_gt_chipset_flush(eb->engine->gt);
return 0;
+err_fini:
+ ww_acquire_fini(&acquire);
err_skip:
i915_request_set_error_once(eb->request, err);
return err;
@@ -1952,9 +1976,10 @@ static int eb_parse(struct i915_execbuffer *eb)
if (err)
goto err_trampoline;
- eb->vma[eb->buffer_count].vma = i915_vma_get(shadow);
- eb->vma[eb->buffer_count].flags = __EXEC_OBJECT_HAS_PIN;
eb->batch = &eb->vma[eb->buffer_count++];
+ eb->batch->vma = i915_vma_get(shadow);
+ eb->batch->flags = __EXEC_OBJECT_HAS_PIN;
+ list_add_tail(&eb->batch->submit_link, &eb->submit_list);
eb->vma[eb->buffer_count].vma = NULL;
eb->trampoline = trampoline;
Just a temporary stage... are we reviewing those? Best if they can be
avoided.
Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Regards,
Tvrtko
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