On Thu, Sep 01, 2022 at 08:58:57AM +0100, Tvrtko Ursulin wrote:
On 01/09/2022 06:09, Niranjana Vishwanathapura wrote:
On Wed, Aug 31, 2022 at 08:38:48AM +0100, Tvrtko Ursulin wrote:
On 27/08/2022 20:43, Andi Shyti wrote:
From: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx>
Implement new execbuf3 ioctl (I915_GEM_EXECBUFFER3) which only
works in vm_bind mode. The vm_bind mode only works with
this new execbuf3 ioctl.
The new execbuf3 ioctl will not have any list of objects to validate
bind as all required objects binding would have been requested by the
userspace before submitting the execbuf3.
And the legacy support like relocations etc are removed.
Signed-off-by: Niranjana Vishwanathapura
<niranjana.vishwanathapura@xxxxxxxxx>
Signed-off-by: Ramalingam C <ramalingam.c@xxxxxxxxx>
Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
---
[snip]
+static void signal_fence_array(const struct i915_execbuffer *eb,
+ struct dma_fence * const fence)
+{
+ unsigned int n;
+
+ for (n = 0; n < eb->num_fences; n++) {
+ struct drm_syncobj *syncobj;
+ unsigned int flags;
+
+ syncobj = ptr_unpack_bits(eb->fences[n].syncobj, &flags, 2);
+ if (!(flags & I915_TIMELINE_FENCE_SIGNAL))
+ continue;
+
+ if (eb->fences[n].chain_fence) {
+ drm_syncobj_add_point(syncobj,
+ eb->fences[n].chain_fence,
+ fence,
+ eb->fences[n].value);
+ /*
+ * The chain's ownership is transferred to the
+ * timeline.
+ */
+ eb->fences[n].chain_fence = NULL;
+ } else {
+ drm_syncobj_replace_fence(syncobj, fence);
+ }
+ }
+}
Semi-random place to ask - how many of the code here is direct
copy of existing functions from i915_gem_execbuffer.c? There seems
to be some 100% copies at least. And then some more with small
tweaks. Spend some time and try to figure out some code sharing?
During VM_BIND design review, maintainers expressed thought on keeping
execbuf3 completely separate and not touch the legacy execbuf path.
Got a link so this maintainer can see what exactly was said? Just to
make sure there isn't any misunderstanding on what "completely
separate" means to different people.
Here is one (search for copypaste/copy-paste)
https://patchwork.freedesktop.org/patch/486608/?series=93447&rev=3
It is hard to search for old discussion threads. May be maintainers
can provide feedback here directly. Dave, Daniel? :)
I also think, execbuf3 should be fully separate. We can do some code
sharing where is a close 100% copy (there is a TODO in cover letter).
There are some changes like the timeline fence array handling here
which looks similar, but the uapi is not exactly the same. Probably,
we should keep them separate and not try to force code sharing at
least at this point.
Okay did not spot that TODO in the cover. But fair since it is RFC to
be unfinished.
I do however think it should be improved before considering the merge.
Because looking at the patch, 100% copies are:
for_each_batch_create_order
for_each_batch_add_order
eb_throttle
eb_pin_timeline
eb_pin_engine
eb_put_engine
__free_fence_array
put_fence_array
await_fence_array
signal_fence_array
retire_requests
eb_request_add
eb_requests_get
eb_requests_put
eb_find_context
Quite a lot.
Then there is a bunch of almost same functions which could be shared
if there weren't two incompatible local struct i915_execbuffer's.
Especially given when the out fence TODO item gets handled a chunk
more will also become a 100% copy.
There are difinitely a few which is 100% copies hence should have a
shared code.
But some are not. Like, fence_array stuff though looks very similar,
the uapi structures are different between execbuf3 and legacy execbuf.
The internal flags are also different (eg., __EXEC3_ENGINE_PINNED vs
__EXEC_ENGINE_PINNED) which causes minor differences hence not a
100% copy.
So, I am not convinced if it is worth carrying legacy stuff into
execbuf3 code. I think we need to look at these on a case by case
basis and see if abstracting common functionality to a separate
shared code makes sense or it is better to keep the code separate.
This could be done by having a common struct i915_execbuffer and then
eb2 and eb3 specific parts which inherit from it. After that is done
it should be easier to see if it makes sense to do something more and
how.
I am not a big fan of it. I think we should not try to load the execbuf3
code with the legacy stuff.
Niranjana
Regards,
Tvrtko
