[Intel-xe] [PATCH v2 08/31] drm/xe: VM LRU bulk move

[Thomas Hellström]

On 5/10/23 20:40, Matthew Brost wrote:
> On Wed, May 10, 2023 at 10:14:12AM +0200, Thomas Hellström wrote:
>> On 5/10/23 00:05, Matthew Brost wrote:
>>> On Tue, May 09, 2023 at 02:47:54PM +0200, Thomas Hellström wrote:
>>>> On 5/2/23 02:17, Matthew Brost wrote:
>>>>> Use the TTM LRU bulk move for BOs tied to a VM. Update the bulk moves
>>>>> LRU position on every exec.
>>>>>
>>>>> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
>>>>> ---
>>>>>     drivers/gpu/drm/xe/xe_bo.c       | 32 ++++++++++++++++++++++++++++----
>>>>>     drivers/gpu/drm/xe/xe_bo.h       |  4 ++--
>>>>>     drivers/gpu/drm/xe/xe_dma_buf.c  |  2 +-
>>>>>     drivers/gpu/drm/xe/xe_exec.c     |  6 ++++++
>>>>>     drivers/gpu/drm/xe/xe_vm_types.h |  3 +++
>>>>>     5 files changed, 40 insertions(+), 7 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
>>>>> index 3ab404e33fae..da99ee53e7d7 100644
>>>>> --- a/drivers/gpu/drm/xe/xe_bo.c
>>>>> +++ b/drivers/gpu/drm/xe/xe_bo.c
>>>>> @@ -985,6 +985,23 @@ static void xe_gem_object_free(struct drm_gem_object *obj)
>>>>>     	ttm_bo_put(container_of(obj, struct ttm_buffer_object, base));
>>>>>     }
>>>>> +static void xe_gem_object_close(struct drm_gem_object *obj,
>>>>> +				struct drm_file *file_priv)
>>>>> +{
>>>>> +	struct xe_bo *bo = gem_to_xe_bo(obj);
>>>>> +
>>>>> +	if (bo->vm && !xe_vm_no_dma_fences(bo->vm)) {
>>>> Is there a reason we don't use bulk moves for LR vms? Admittedly bumping LRU
>>>> doesn't make much sense when we support user-space command buffer chaining,
>>>> but I think we should be doing it on exec at least, no?
>>> Maybe you could make the argument for compute VMs, the preempt worker in
>>> that case should probably do a bulk move. I can change this if desired.
>> Yes, please.
>>> Fot a fault VM it makes no sense as the fault handler updates the LRU
>>> for individual BOs.
>> Yes that makes sense.
>>>>> +		struct ww_acquire_ctx ww;
>>>>> +
>>>>> +		XE_BUG_ON(!xe_bo_is_user(bo));
>>>> Also why can't we use this for kernel objects as well? At some point we want
>>>> to get to evictable page-table objects? Could we do this in the
>>>> release_notify() callback to cover all potential bos?
>>>>
>>> xe_gem_object_close is a user call, right? We can't call this on kernel
>>> BOs. This also could be outside the if statement.
>> Hmm, yes the question was can we stop doing this in xe_gem_object_close()
>> and instead do it in release_notify() to cover also kernel objects. Since
>> release_notify() is called just after individualizing dma_resv, it makes
>> sense to individualize also LRU at that point?
>>
> If we ever support moving kernel BOs, then yes. We need to do a lot of
> work to get there, with I'd rather leave this where is but I'll add a
> comment indicating if we want to support kernel BO eviction, this should
> be updated.
>
> Sound good?

Well, I can't see the motivation to have it in gem close? Are other 
drivers doing that? Whether the object should be bulk moved or not is 
tied to whether it's a vm private object or not and that is closely tied 
to whether the reservation object is the vm resv or the object resv?

/Thomas

>
> Matt
>
>> /Thomas
>>
>>
>>> Matt
>>>
>>>> /Thomas
>>>>
>>>>