Re: [PATCH] drm/ttm: replace dma_resv object on deleted BOs v3
> 2020年2月13日 18:01，Koenig, Christian 写道：
>
> Am 13.02.20 um 05:11 schrieb Pan, Xinhui:
>>
>>
>>> 2020年2月12日 19:53，Christian König 写道：
>>>
>>> Am 12.02.20 um 07:23 schrieb Pan, Xinhui:
> 2020年2月11日 23:43，Christian König 写道：
>
> When non-imported BOs are resurrected for delayed delete we replace
> the dma_resv object to allow for easy reclaiming of the resources.
>
> v2: move that to ttm_bo_individualize_resv
> v3: add a comment to explain what's going on
>
> Signed-off-by: Christian König
> Reviewed-by: xinhui pan
> ---
> drivers/gpu/drm/ttm/ttm_bo.c | 14 +-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index bfc42a9e4fb4..8174603d390f 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -393,6 +393,18 @@ static int ttm_bo_individualize_resv(struct
> ttm_buffer_object *bo)
>
> r = dma_resv_copy_fences(>base._resv, bo->base.resv);
> dma_resv_unlock(>base._resv);
> + if (r)
> + return r;
> +
> + if (bo->type != ttm_bo_type_sg) {
> + /* This works because the BO is about to be destroyed and nobody
> + * reference it any more. The only tricky case is the trylock on
> + * the resv object while holding the lru_lock.
> + */
> + spin_lock(_bo_glob.lru_lock);
> + bo->base.resv = >base._resv;
> + spin_unlock(_bo_glob.lru_lock);
> + }
>
how about something like that.
the basic idea is to do the bo cleanup work in bo release first and avoid
any race with evict.
As in bo dieing progress, evict also just do bo cleanup work.
If bo is busy, neither bo_release nor evict can do cleanupwork on it.
For the bo release case, we just add bo back to lru list.
So we can clean it up both in workqueue and shrinker as the past way did.
@@ -405,8 +405,9 @@ static int ttm_bo_individualize_resv(struct
ttm_buffer_object *bo)
if (bo->type != ttm_bo_type_sg) {
spin_lock(_bo_glob.lru_lock);
- bo->base.resv = >base._resv;
+ ttm_bo_del_from_lru(bo);
spin_unlock(_bo_glob.lru_lock);
+ bo->base.resv = >base._resv;
}
return r;
@@ -606,10 +607,9 @@ static void ttm_bo_release(struct kref *kref)
* shrinkers, now that they are queued for
* destruction.
*/
- if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT) {
+ if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT)
bo->mem.placement &= ~TTM_PL_FLAG_NO_EVICT;
- ttm_bo_move_to_lru_tail(bo, NULL);
- }
+ ttm_bo_add_mem_to_lru(bo, >mem);
kref_init(>kref);
list_add_tail(>ddestroy, >ddestroy);
>>> Yeah, thought about that as well. But this has the major drawback that the
>>> deleted BO moves to the end of the LRU, which is something we don't want.
>> well, as the bo is busy, looks like it needs time to being idle. putting it
>> to tail seems fair.
>
> No, see BOs should move to the tail of the LRU whenever they are used.
> Freeing up a BO is basically the opposite of using it.
>
> So what would happen on the next memory contention is that the MM would evict
> BOs which are still used and only after come to the delete BO which could
> have been removed long ago.
>
>>> I think the real solution to this problem is to go a completely different
>>> way and remove the delayed delete feature from TTM altogether. Instead this
>>> should be part of some DRM domain handler component.
>>>
>> yes, completely agree. As long as we can shrink bos when OOM, the workqueue
>> is not necessary, The workqueue does not help in a heavy workload case.
>>
>> Pls see my patches below, I remove the workqueue, and what’s more, we can
>> clearup the bo without lru lock hold.
>> That would reduce the lock contention. I run kfdtest and got a good
>> performance result.
>
> No, that's an approach we had before as well and it also doesn't work that
> well.
>
> See the problem is that we can only remove the BO from the LRU after it has
> released the memory it references. Otherwise we run into the issue that some
> threads can't wait for the memory to be freed any more and run into an OOM
> situation.
>
ok, we can keep the workqueue at it is.
Now I come up with another idea that evict and swap can touch the destroy list
first, then lru list.
Looks like putting a dieing bo in lru list is useless.
thanks
xinhui
> Regards,
> Christian.
>
>>
>>
>>> In other words it should not matter if a BO is evicted, moved or freed.
>>> Whenever a piece of memory becomes available again we keep around a fence
>>> which marks the end of using this piece of memory.
>>>
>>> When then
Re: [PATCH] drm/ttm: replace dma_resv object on deleted BOs v3
Am 13.02.20 um 05:11 schrieb Pan, Xinhui:
2020年2月12日 19:53，Christian König 写道：
Am 12.02.20 um 07:23 schrieb Pan, Xinhui:
2020年2月11日 23:43，Christian König 写道：
When non-imported BOs are resurrected for delayed delete we replace
the dma_resv object to allow for easy reclaiming of the resources.
v2: move that to ttm_bo_individualize_resv
v3: add a comment to explain what's going on
Signed-off-by: Christian König
Reviewed-by: xinhui pan
---
drivers/gpu/drm/ttm/ttm_bo.c | 14 +-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index bfc42a9e4fb4..8174603d390f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -393,6 +393,18 @@ static int ttm_bo_individualize_resv(struct
ttm_buffer_object *bo)
r = dma_resv_copy_fences(>base._resv, bo->base.resv);
dma_resv_unlock(>base._resv);
+ if (r)
+ return r;
+
+ if (bo->type != ttm_bo_type_sg) {
+ /* This works because the BO is about to be destroyed and nobody
+* reference it any more. The only tricky case is the trylock on
+* the resv object while holding the lru_lock.
+*/
+ spin_lock(_bo_glob.lru_lock);
+ bo->base.resv = >base._resv;
+ spin_unlock(_bo_glob.lru_lock);
+ }
how about something like that.
the basic idea is to do the bo cleanup work in bo release first and avoid any
race with evict.
As in bo dieing progress, evict also just do bo cleanup work.
If bo is busy, neither bo_release nor evict can do cleanupwork on it. For the
bo release case, we just add bo back to lru list.
So we can clean it up both in workqueue and shrinker as the past way did.
@@ -405,8 +405,9 @@ static int ttm_bo_individualize_resv(struct
ttm_buffer_object *bo)
if (bo->type != ttm_bo_type_sg) {
spin_lock(_bo_glob.lru_lock);
- bo->base.resv = >base._resv;
+ ttm_bo_del_from_lru(bo);
spin_unlock(_bo_glob.lru_lock);
+ bo->base.resv = >base._resv;
}
return r;
@@ -606,10 +607,9 @@ static void ttm_bo_release(struct kref *kref)
* shrinkers, now that they are queued for
* destruction.
*/
- if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT) {
+ if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT)
bo->mem.placement &= ~TTM_PL_FLAG_NO_EVICT;
- ttm_bo_move_to_lru_tail(bo, NULL);
- }
+ ttm_bo_add_mem_to_lru(bo, >mem);
kref_init(>kref);
list_add_tail(>ddestroy, >ddestroy);
Yeah, thought about that as well. But this has the major drawback that the
deleted BO moves to the end of the LRU, which is something we don't want.
well, as the bo is busy, looks like it needs time to being idle. putting it to
tail seems fair.
No, see BOs should move to the tail of the LRU whenever they are used.
Freeing up a BO is basically the opposite of using it.
So what would happen on the next memory contention is that the MM would
evict BOs which are still used and only after come to the delete BO
which could have been removed long ago.
I think the real solution to this problem is to go a completely different way
and remove the delayed delete feature from TTM altogether. Instead this should
be part of some DRM domain handler component.
yes, completely agree. As long as we can shrink bos when OOM, the workqueue is
not necessary, The workqueue does not help in a heavy workload case.
Pls see my patches below, I remove the workqueue, and what’s more, we can
clearup the bo without lru lock hold.
That would reduce the lock contention. I run kfdtest and got a good performance
result.
No, that's an approach we had before as well and it also doesn't work
that well.
See the problem is that we can only remove the BO from the LRU after it
has released the memory it references. Otherwise we run into the issue
that some threads can't wait for the memory to be freed any more and run
into an OOM situation.
Regards,
Christian.
In other words it should not matter if a BO is evicted, moved or freed.
Whenever a piece of memory becomes available again we keep around a fence which
marks the end of using this piece of memory.
When then somebody asks for new memory we work through the LRU and test if
using a certain piece of memory makes sense or not. If we find that a BO needs
to be evicted for this we return a reference to the BO in question to the upper
level handling.
If we find that we can do the allocation but only with recently freed up memory
we gather the fences and say you can only use the newly allocated memory after
waiting for those.
HEY! Wait a second! Did I just outlined what a potential replacement to TTM
would look like?
yes, that is a good picture. Looks like we could do more work hen. :)
thanks
xinhui
--git a/drivers/gpu/drm/ttm/ttm_bo.c
Re: [PATCH] drm/ttm: replace dma_resv object on deleted BOs v3
> 2020年2月12日 19:53，Christian König 写道：
>
> Am 12.02.20 um 07:23 schrieb Pan, Xinhui:
>>
>>> 2020年2月11日 23:43，Christian König 写道：
>>>
>>> When non-imported BOs are resurrected for delayed delete we replace
>>> the dma_resv object to allow for easy reclaiming of the resources.
>>>
>>> v2: move that to ttm_bo_individualize_resv
>>> v3: add a comment to explain what's going on
>>>
>>> Signed-off-by: Christian König
>>> Reviewed-by: xinhui pan
>>> ---
>>> drivers/gpu/drm/ttm/ttm_bo.c | 14 +-
>>> 1 file changed, 13 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
>>> index bfc42a9e4fb4..8174603d390f 100644
>>> --- a/drivers/gpu/drm/ttm/ttm_bo.c
>>> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
>>> @@ -393,6 +393,18 @@ static int ttm_bo_individualize_resv(struct
>>> ttm_buffer_object *bo)
>>>
>>> r = dma_resv_copy_fences(>base._resv, bo->base.resv);
>>> dma_resv_unlock(>base._resv);
>>> + if (r)
>>> + return r;
>>> +
>>> + if (bo->type != ttm_bo_type_sg) {
>>> + /* This works because the BO is about to be destroyed and nobody
>>> +* reference it any more. The only tricky case is the trylock on
>>> +* the resv object while holding the lru_lock.
>>> +*/
>>> + spin_lock(_bo_glob.lru_lock);
>>> + bo->base.resv = >base._resv;
>>> + spin_unlock(_bo_glob.lru_lock);
>>> + }
>>>
>> how about something like that.
>> the basic idea is to do the bo cleanup work in bo release first and avoid
>> any race with evict.
>> As in bo dieing progress, evict also just do bo cleanup work.
>>
>> If bo is busy, neither bo_release nor evict can do cleanupwork on it. For
>> the bo release case, we just add bo back to lru list.
>> So we can clean it up both in workqueue and shrinker as the past way did.
>>
>> @@ -405,8 +405,9 @@ static int ttm_bo_individualize_resv(struct
>> ttm_buffer_object *bo)
>> if (bo->type != ttm_bo_type_sg) {
>> spin_lock(_bo_glob.lru_lock);
>> - bo->base.resv = >base._resv;
>> + ttm_bo_del_from_lru(bo);
>> spin_unlock(_bo_glob.lru_lock);
>> + bo->base.resv = >base._resv;
>> }
>> return r;
>> @@ -606,10 +607,9 @@ static void ttm_bo_release(struct kref *kref)
>> * shrinkers, now that they are queued for
>> * destruction.
>> */
>> - if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT) {
>> + if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT)
>> bo->mem.placement &= ~TTM_PL_FLAG_NO_EVICT;
>> - ttm_bo_move_to_lru_tail(bo, NULL);
>> - }
>> + ttm_bo_add_mem_to_lru(bo, >mem);
>> kref_init(>kref);
>> list_add_tail(>ddestroy, >ddestroy);
>
> Yeah, thought about that as well. But this has the major drawback that the
> deleted BO moves to the end of the LRU, which is something we don't want.
well, as the bo is busy, looks like it needs time to being idle. putting it to
tail seems fair.
> I think the real solution to this problem is to go a completely different way
> and remove the delayed delete feature from TTM altogether. Instead this
> should be part of some DRM domain handler component.
>
yes, completely agree. As long as we can shrink bos when OOM, the workqueue is
not necessary, The workqueue does not help in a heavy workload case.
Pls see my patches below, I remove the workqueue, and what’s more, we can
clearup the bo without lru lock hold.
That would reduce the lock contention. I run kfdtest and got a good performance
result.
> In other words it should not matter if a BO is evicted, moved or freed.
> Whenever a piece of memory becomes available again we keep around a fence
> which marks the end of using this piece of memory.
>
> When then somebody asks for new memory we work through the LRU and test if
> using a certain piece of memory makes sense or not. If we find that a BO
> needs to be evicted for this we return a reference to the BO in question to
> the upper level handling.
>
> If we find that we can do the allocation but only with recently freed up
> memory we gather the fences and say you can only use the newly allocated
> memory after waiting for those.
>
> HEY! Wait a second! Did I just outlined what a potential replacement to TTM
> would look like?
yes, that is a good picture. Looks like we could do more work hen. :)
thanks
xinhui
--git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index e795d5b5f8af..ac826a09b4ec 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -405,6 +405,9 @@ static int ttm_bo_individualize_resv(struct
ttm_buffer_object *bo)
if (bo->type != ttm_bo_type_sg) {
spin_lock(_bo_glob.lru_lock);
+ /* it is very likely to release bo successfully.
+* if not, just adding it back.
+*/
ttm_bo_del_from_lru(bo);
Re: [PATCH] drm/ttm: replace dma_resv object on deleted BOs v3
On Wed, Feb 12, 2020 at 12:53 PM Christian König
wrote:
>
> Am 12.02.20 um 07:23 schrieb Pan, Xinhui:
> >
> >> 2020年2月11日 23:43，Christian König 写道：
> >>
> >> When non-imported BOs are resurrected for delayed delete we replace
> >> the dma_resv object to allow for easy reclaiming of the resources.
> >>
> >> v2: move that to ttm_bo_individualize_resv
> >> v3: add a comment to explain what's going on
> >>
> >> Signed-off-by: Christian König
> >> Reviewed-by: xinhui pan
> >> ---
> >> drivers/gpu/drm/ttm/ttm_bo.c | 14 +-
> >> 1 file changed, 13 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> >> index bfc42a9e4fb4..8174603d390f 100644
> >> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> >> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> >> @@ -393,6 +393,18 @@ static int ttm_bo_individualize_resv(struct
> >> ttm_buffer_object *bo)
> >>
> >> r = dma_resv_copy_fences(>base._resv, bo->base.resv);
> >> dma_resv_unlock(>base._resv);
> >> +if (r)
> >> +return r;
> >> +
> >> +if (bo->type != ttm_bo_type_sg) {
> >> +/* This works because the BO is about to be destroyed and
> >> nobody
> >> + * reference it any more. The only tricky case is the trylock
> >> on
> >> + * the resv object while holding the lru_lock.
> >> + */
> >> +spin_lock(_bo_glob.lru_lock);
> >> +bo->base.resv = >base._resv;
> >> +spin_unlock(_bo_glob.lru_lock);
> >> +}
> >>
> > how about something like that.
> > the basic idea is to do the bo cleanup work in bo release first and avoid
> > any race with evict.
> > As in bo dieing progress, evict also just do bo cleanup work.
> >
> > If bo is busy, neither bo_release nor evict can do cleanupwork on it. For
> > the bo release case, we just add bo back to lru list.
> > So we can clean it up both in workqueue and shrinker as the past way did.
> >
> > @@ -405,8 +405,9 @@ static int ttm_bo_individualize_resv(struct
> > ttm_buffer_object *bo)
> >
> > if (bo->type != ttm_bo_type_sg) {
> > spin_lock(_bo_glob.lru_lock);
> > - bo->base.resv = >base._resv;
> > + ttm_bo_del_from_lru(bo);
> > spin_unlock(_bo_glob.lru_lock);
> > + bo->base.resv = >base._resv;
> > }
> >
> > return r;
> > @@ -606,10 +607,9 @@ static void ttm_bo_release(struct kref *kref)
> > * shrinkers, now that they are queued for
> > * destruction.
> > */
> > - if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT) {
> > + if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT)
> > bo->mem.placement &= ~TTM_PL_FLAG_NO_EVICT;
> > - ttm_bo_move_to_lru_tail(bo, NULL);
> > - }
> > + ttm_bo_add_mem_to_lru(bo, >mem);
> >
> > kref_init(>kref);
> > list_add_tail(>ddestroy, >ddestroy);
>
> Yeah, thought about that as well. But this has the major drawback that
> the deleted BO moves to the end of the LRU, which is something we don't
> want.
>
> I think the real solution to this problem is to go a completely
> different way and remove the delayed delete feature from TTM altogether.
> Instead this should be part of some DRM domain handler component.
>
> In other words it should not matter if a BO is evicted, moved or freed.
> Whenever a piece of memory becomes available again we keep around a
> fence which marks the end of using this piece of memory.
>
> When then somebody asks for new memory we work through the LRU and test
> if using a certain piece of memory makes sense or not. If we find that a
> BO needs to be evicted for this we return a reference to the BO in
> question to the upper level handling.
>
> If we find that we can do the allocation but only with recently freed up
> memory we gather the fences and say you can only use the newly allocated
> memory after waiting for those.
>
> HEY! Wait a second! Did I just outlined what a potential replacement to
> TTM would look like?
Hm I thought that was (roughly) the idea behind the last_move fence in
the ttm allocation manager? Except it's gloabl, so you'd want to have
it slightly more fine-grained. But if your vram can essentially be
managed as pages, because (almost) no need for contig allocations,
then tracking all that gets a bit nasty ...
Anyway, I think the ghost object trickery is indeed not great, since
it mixes up fences for one thing (objects) with fences for allocated
ranges in the underlying resource. Another mismatch I'm seeing is that
ttm doesn't even track (or bothers) vma ranges. So you have that
additional fun with "the memory is gone, but the ptes are kinda still
there". I guess you could also solve that by tracking such usage at
the allocation manager level, with some fences that track the async
pte update job. I guess that's your plan, I'm not sure that fits with
all the ideas we have with fancy new submission models (stuff like
what amdkfd is doing).
-Daniel
Daniel Vetter
Re: [PATCH] drm/ttm: replace dma_resv object on deleted BOs v3
Am 12.02.20 um 07:23 schrieb Pan, Xinhui:
2020年2月11日 23:43，Christian König 写道：
When non-imported BOs are resurrected for delayed delete we replace
the dma_resv object to allow for easy reclaiming of the resources.
v2: move that to ttm_bo_individualize_resv
v3: add a comment to explain what's going on
Signed-off-by: Christian König
Reviewed-by: xinhui pan
---
drivers/gpu/drm/ttm/ttm_bo.c | 14 +-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index bfc42a9e4fb4..8174603d390f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -393,6 +393,18 @@ static int ttm_bo_individualize_resv(struct
ttm_buffer_object *bo)
r = dma_resv_copy_fences(>base._resv, bo->base.resv);
dma_resv_unlock(>base._resv);
+ if (r)
+ return r;
+
+ if (bo->type != ttm_bo_type_sg) {
+ /* This works because the BO is about to be destroyed and nobody
+* reference it any more. The only tricky case is the trylock on
+* the resv object while holding the lru_lock.
+*/
+ spin_lock(_bo_glob.lru_lock);
+ bo->base.resv = >base._resv;
+ spin_unlock(_bo_glob.lru_lock);
+ }
how about something like that.
the basic idea is to do the bo cleanup work in bo release first and avoid any
race with evict.
As in bo dieing progress, evict also just do bo cleanup work.
If bo is busy, neither bo_release nor evict can do cleanupwork on it. For the
bo release case, we just add bo back to lru list.
So we can clean it up both in workqueue and shrinker as the past way did.
@@ -405,8 +405,9 @@ static int ttm_bo_individualize_resv(struct
ttm_buffer_object *bo)
if (bo->type != ttm_bo_type_sg) {
spin_lock(_bo_glob.lru_lock);
- bo->base.resv = >base._resv;
+ ttm_bo_del_from_lru(bo);
spin_unlock(_bo_glob.lru_lock);
+ bo->base.resv = >base._resv;
}
return r;
@@ -606,10 +607,9 @@ static void ttm_bo_release(struct kref *kref)
* shrinkers, now that they are queued for
* destruction.
*/
- if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT) {
+ if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT)
bo->mem.placement &= ~TTM_PL_FLAG_NO_EVICT;
- ttm_bo_move_to_lru_tail(bo, NULL);
- }
+ ttm_bo_add_mem_to_lru(bo, >mem);
kref_init(>kref);
list_add_tail(>ddestroy, >ddestroy);
Yeah, thought about that as well. But this has the major drawback that
the deleted BO moves to the end of the LRU, which is something we don't
want.
I think the real solution to this problem is to go a completely
different way and remove the delayed delete feature from TTM altogether.
Instead this should be part of some DRM domain handler component.
In other words it should not matter if a BO is evicted, moved or freed.
Whenever a piece of memory becomes available again we keep around a
fence which marks the end of using this piece of memory.
When then somebody asks for new memory we work through the LRU and test
if using a certain piece of memory makes sense or not. If we find that a
BO needs to be evicted for this we return a reference to the BO in
question to the upper level handling.
If we find that we can do the allocation but only with recently freed up
memory we gather the fences and say you can only use the newly allocated
memory after waiting for those.
HEY! Wait a second! Did I just outlined what a potential replacement to
TTM would look like?
Cheers,
Christian.
thanks
xinhui
return r;
}
@@ -724,7 +736,7 @@ static bool ttm_bo_evict_swapout_allowable(struct
ttm_buffer_object *bo,
if (bo->base.resv == ctx->resv) {
dma_resv_assert_held(bo->base.resv);
- if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT || bo->deleted)
+ if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT)
ret = true;
*locked = false;
if (busy)
--
2.17.1
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Re: [PATCH] drm/ttm: replace dma_resv object on deleted BOs v3
> 2020年2月11日 23:43，Christian König 写道：
>
> When non-imported BOs are resurrected for delayed delete we replace
> the dma_resv object to allow for easy reclaiming of the resources.
>
> v2: move that to ttm_bo_individualize_resv
> v3: add a comment to explain what's going on
>
> Signed-off-by: Christian König
> Reviewed-by: xinhui pan
> ---
> drivers/gpu/drm/ttm/ttm_bo.c | 14 +-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index bfc42a9e4fb4..8174603d390f 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -393,6 +393,18 @@ static int ttm_bo_individualize_resv(struct
> ttm_buffer_object *bo)
>
> r = dma_resv_copy_fences(>base._resv, bo->base.resv);
> dma_resv_unlock(>base._resv);
> + if (r)
> + return r;
> +
> + if (bo->type != ttm_bo_type_sg) {
> + /* This works because the BO is about to be destroyed and nobody
> + * reference it any more. The only tricky case is the trylock on
> + * the resv object while holding the lru_lock.
> + */
> + spin_lock(_bo_glob.lru_lock);
> + bo->base.resv = >base._resv;
> + spin_unlock(_bo_glob.lru_lock);
> + }
>
how about something like that.
the basic idea is to do the bo cleanup work in bo release first and avoid any
race with evict.
As in bo dieing progress, evict also just do bo cleanup work.
If bo is busy, neither bo_release nor evict can do cleanupwork on it. For the
bo release case, we just add bo back to lru list.
So we can clean it up both in workqueue and shrinker as the past way did.
@@ -405,8 +405,9 @@ static int ttm_bo_individualize_resv(struct
ttm_buffer_object *bo)
if (bo->type != ttm_bo_type_sg) {
spin_lock(_bo_glob.lru_lock);
- bo->base.resv = >base._resv;
+ ttm_bo_del_from_lru(bo);
spin_unlock(_bo_glob.lru_lock);
+ bo->base.resv = >base._resv;
}
return r;
@@ -606,10 +607,9 @@ static void ttm_bo_release(struct kref *kref)
* shrinkers, now that they are queued for
* destruction.
*/
- if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT) {
+ if (bo->mem.placement & TTM_PL_FLAG_NO_EVICT)
bo->mem.placement &= ~TTM_PL_FLAG_NO_EVICT;
- ttm_bo_move_to_lru_tail(bo, NULL);
- }
+ ttm_bo_add_mem_to_lru(bo, >mem);
kref_init(>kref);
list_add_tail(>ddestroy, >ddestroy);
thanks
xinhui
> return r;
> }
> @@ -724,7 +736,7 @@ static bool ttm_bo_evict_swapout_allowable(struct
> ttm_buffer_object *bo,
>
> if (bo->base.resv == ctx->resv) {
> dma_resv_assert_held(bo->base.resv);
> - if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT || bo->deleted)
> + if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT)
> ret = true;
> *locked = false;
> if (busy)
> --
> 2.17.1
>
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Re: [PATCH] drm/ttm: replace dma_resv object on deleted BOs v3
On Tue, Feb 11, 2020 at 04:43:26PM +0100, Christian König wrote:
> When non-imported BOs are resurrected for delayed delete we replace
> the dma_resv object to allow for easy reclaiming of the resources.
>
> v2: move that to ttm_bo_individualize_resv
> v3: add a comment to explain what's going on
>
> Signed-off-by: Christian König
> Reviewed-by: xinhui pan
> ---
> drivers/gpu/drm/ttm/ttm_bo.c | 14 +-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index bfc42a9e4fb4..8174603d390f 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -393,6 +393,18 @@ static int ttm_bo_individualize_resv(struct
> ttm_buffer_object *bo)
>
> r = dma_resv_copy_fences(>base._resv, bo->base.resv);
> dma_resv_unlock(>base._resv);
> + if (r)
> + return r;
> +
> + if (bo->type != ttm_bo_type_sg) {
> + /* This works because the BO is about to be destroyed and nobody
> + * reference it any more. The only tricky case is the trylock on
> + * the resv object while holding the lru_lock.
> + */
I'm foolish enough to believe this is correct :-)
Reviewed-by: Daniel Vetter
> + spin_lock(_bo_glob.lru_lock);
> + bo->base.resv = >base._resv;
> + spin_unlock(_bo_glob.lru_lock);
> + }
>
> return r;
> }
> @@ -724,7 +736,7 @@ static bool ttm_bo_evict_swapout_allowable(struct
> ttm_buffer_object *bo,
>
> if (bo->base.resv == ctx->resv) {
> dma_resv_assert_held(bo->base.resv);
> - if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT || bo->deleted)
> + if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT)
> ret = true;
> *locked = false;
> if (busy)
> --
> 2.17.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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[PATCH] drm/ttm: replace dma_resv object on deleted BOs v3
When non-imported BOs are resurrected for delayed delete we replace
the dma_resv object to allow for easy reclaiming of the resources.
v2: move that to ttm_bo_individualize_resv
v3: add a comment to explain what's going on
Signed-off-by: Christian König
Reviewed-by: xinhui pan
---
drivers/gpu/drm/ttm/ttm_bo.c | 14 +-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index bfc42a9e4fb4..8174603d390f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -393,6 +393,18 @@ static int ttm_bo_individualize_resv(struct
ttm_buffer_object *bo)
r = dma_resv_copy_fences(>base._resv, bo->base.resv);
dma_resv_unlock(>base._resv);
+ if (r)
+ return r;
+
+ if (bo->type != ttm_bo_type_sg) {
+ /* This works because the BO is about to be destroyed and nobody
+* reference it any more. The only tricky case is the trylock on
+* the resv object while holding the lru_lock.
+*/
+ spin_lock(_bo_glob.lru_lock);
+ bo->base.resv = >base._resv;
+ spin_unlock(_bo_glob.lru_lock);
+ }
return r;
}
@@ -724,7 +736,7 @@ static bool ttm_bo_evict_swapout_allowable(struct
ttm_buffer_object *bo,
if (bo->base.resv == ctx->resv) {
dma_resv_assert_held(bo->base.resv);
- if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT || bo->deleted)
+ if (ctx->flags & TTM_OPT_FLAG_ALLOW_RES_EVICT)
ret = true;
*locked = false;
if (busy)
--
2.17.1
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