[PATCH 1/2] [WIP]drm/ttm: add waiter list to prevent allocation not in order
Christian König
ckoenig.leichtzumerken at gmail.com
Fri Jan 26 12:43:42 UTC 2018
> After my investigation, this issue should be detect of TTM design
> self, which breaks scheduling balance.
Yeah, but again. This is indented design we can't change easily.
Regards,
Christian.
Am 26.01.2018 um 13:36 schrieb Zhou, David(ChunMing):
> I am off work, so reply mail by phone, the format could not be text.
>
> back to topic itself:
> the problem indeed happen on amdgpu driver, someone reports me that
> application runs with two instances, the performance are different.
> I also reproduced the issue with unit test(bo_eviction_test). They
> always think our scheduler isn't working as expected.
>
> After my investigation, this issue should be detect of TTM design
> self, which breaks scheduling balance.
>
> Further, if we run containers for our gpu, container A could run high
> score, container B runs low score with same benchmark.
>
> So this is bug that we need fix.
>
> Regards,
> David Zhou
>
> 发自坚果 Pro
>
> Christian K鰊ig <ckoenig.leichtzumerken at gmail.com> 于 2018年1月26日
> 下午6:31写道：
>
> Am 26.01.2018 um 11:22 schrieb Chunming Zhou:
> > there is a scheduling balance issue about get node like:
> > a. process A allocates full memory and use it for submission.
> > b. process B tries to allocates memory, will wait for process A BO
> idle in eviction.
> > c. process A completes the job, process B eviction will put process
> A BO node,
> > but in the meantime, process C is comming to allocate BO, whill
> directly get node successfully, and do submission,
> > process B will again wait for process C BO idle.
> > d. repeat the above setps, process B could be delayed much more.
> >
> > later allocation must not be ahead of front in same place.
>
> Again NAK to the whole approach.
>
> At least with amdgpu the problem you described above never occurs
> because evictions are pipelined operations. We could only block for
> deleted regions to become free.
>
> But independent of that incoming memory requests while we make room for
> eviction are intended to be served first.
>
> Changing that is certainly a no-go cause that would favor memory hungry
> applications over small clients.
>
> Regards,
> Christian.
>
> >
> > Change-Id: I3daa892e50f82226c552cc008a29e55894a98f18
> > Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
> > ---
> > drivers/gpu/drm/ttm/ttm_bo.c | 69
> +++++++++++++++++++++++++++++++++++++++--
> > include/drm/ttm/ttm_bo_api.h | 7 +++++
> > include/drm/ttm/ttm_bo_driver.h | 7 +++++
> > 3 files changed, 80 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> > index d33a6bb742a1..558ec2cf465d 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > @@ -841,6 +841,58 @@ static int ttm_bo_add_move_fence(struct
> ttm_buffer_object *bo,
> > return 0;
> > }
> >
> > +static void ttm_man_init_waiter(struct ttm_bo_waiter *waiter,
> > + struct ttm_buffer_object *bo,
> > + const struct ttm_place *place)
> > +{
> > + waiter->tbo = bo;
> > + memcpy((void *)&waiter->place, (void *)place, sizeof(*place));
> > + INIT_LIST_HEAD(&waiter->list);
> > +}
> > +
> > +static void ttm_man_add_waiter(struct ttm_mem_type_manager *man,
> > + struct ttm_bo_waiter *waiter)
> > +{
> > + if (!waiter)
> > + return;
> > + spin_lock(&man->wait_lock);
> > + list_add_tail(&waiter->list, &man->waiter_list);
> > + spin_unlock(&man->wait_lock);
> > +}
> > +
> > +static void ttm_man_del_waiter(struct ttm_mem_type_manager *man,
> > + struct ttm_bo_waiter *waiter)
> > +{
> > + if (!waiter)
> > + return;
> > + spin_lock(&man->wait_lock);
> > + if (!list_empty(&waiter->list))
> > + list_del(&waiter->list);
> > + spin_unlock(&man->wait_lock);
> > + kfree(waiter);
> > +}
> > +
> > +int ttm_man_check_bo(struct ttm_mem_type_manager *man,
> > + struct ttm_buffer_object *bo,
> > + const struct ttm_place *place)
> > +{
> > + struct ttm_bo_waiter *waiter, *tmp;
> > +
> > + spin_lock(&man->wait_lock);
> > + list_for_each_entry_safe(waiter, tmp, &man->waiter_list, list) {
> > + if ((bo != waiter->tbo) &&
> > + ((place->fpfn >= waiter->place.fpfn &&
> > + place->fpfn <= waiter->place.lpfn) ||
> > + (place->lpfn <= waiter->place.lpfn && place->lpfn >=
> > + waiter->place.fpfn)))
> > + goto later_bo;
> > + }
> > + spin_unlock(&man->wait_lock);
> > + return true;
> > +later_bo:
> > + spin_unlock(&man->wait_lock);
> > + return false;
> > +}
> > /**
> > * Repeatedly evict memory from the LRU for @mem_type until we
> create enough
> > * space, or we've evicted everything and there isn't enough space.
> > @@ -853,17 +905,26 @@ static int ttm_bo_mem_force_space(struct
> ttm_buffer_object *bo,
> > {
> > struct ttm_bo_device *bdev = bo->bdev;
> > struct ttm_mem_type_manager *man = &bdev->man[mem_type];
> > + struct ttm_bo_waiter waiter;
> > int ret;
> >
> > + ttm_man_init_waiter(&waiter, bo, place);
> > + ttm_man_add_waiter(man, &waiter);
> > do {
> > ret = (*man->func->get_node)(man, bo, place, mem);
> > - if (unlikely(ret != 0))
> > + if (unlikely(ret != 0)) {
> > + ttm_man_del_waiter(man, &waiter);
> > return ret;
> > - if (mem->mm_node)
> > + }
> > + if (mem->mm_node) {
> > + ttm_man_del_waiter(man, &waiter);
> > break;
> > + }
> > ret = ttm_mem_evict_first(bdev, mem_type, place, ctx);
> > - if (unlikely(ret != 0))
> > + if (unlikely(ret != 0)) {
> > + ttm_man_del_waiter(man, &waiter);
> > return ret;
> > + }
> > } while (1);
> > mem->mem_type = mem_type;
> > return ttm_bo_add_move_fence(bo, man, mem);
> > @@ -1450,6 +1511,8 @@ int ttm_bo_init_mm(struct ttm_bo_device *bdev,
> unsigned type,
> > man->use_io_reserve_lru = false;
> > mutex_init(&man->io_reserve_mutex);
> > spin_lock_init(&man->move_lock);
> > + spin_lock_init(&man->wait_lock);
> > + INIT_LIST_HEAD(&man->waiter_list);
> > INIT_LIST_HEAD(&man->io_reserve_lru);
> >
> > ret = bdev->driver->init_mem_type(bdev, type, man);
> > diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> > index 2cd025c2abe7..0fce4dbd02e7 100644
> > --- a/include/drm/ttm/ttm_bo_api.h
> > +++ b/include/drm/ttm/ttm_bo_api.h
> > @@ -40,6 +40,7 @@
> > #include <linux/mm.h>
> > #include <linux/bitmap.h>
> > #include <linux/reservation.h>
> > +#include <drm/ttm/ttm_placement.h>
> >
> > struct ttm_bo_device;
> >
> > @@ -232,6 +233,12 @@ struct ttm_buffer_object {
> > struct mutex wu_mutex;
> > };
> >
> > +struct ttm_bo_waiter {
> > + struct ttm_buffer_object *tbo;
> > + struct ttm_place place;
> > + struct list_head list;
> > +};
> > +
> > /**
> > * struct ttm_bo_kmap_obj
> > *
> > diff --git a/include/drm/ttm/ttm_bo_driver.h
> b/include/drm/ttm/ttm_bo_driver.h
> > index 9b417eb2df20..dc6b8b4c9e06 100644
> > --- a/include/drm/ttm/ttm_bo_driver.h
> > +++ b/include/drm/ttm/ttm_bo_driver.h
> > @@ -293,6 +293,10 @@ struct ttm_mem_type_manager {
> > bool io_reserve_fastpath;
> > spinlock_t move_lock;
> >
> > + /* waiters in list */
> > + spinlock_t wait_lock;
> > + struct list_head waiter_list;
> > +
> > /*
> > * Protected by @io_reserve_mutex:
> > */
> > @@ -748,6 +752,9 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
> > struct ttm_mem_reg *mem,
> > struct ttm_operation_ctx *ctx);
> >
> > +int ttm_man_check_bo(struct ttm_mem_type_manager *man,
> > + struct ttm_buffer_object *bo,
> > + const struct ttm_place *place);
> > void ttm_bo_mem_put(struct ttm_buffer_object *bo, struct
> ttm_mem_reg *mem);
> > void ttm_bo_mem_put_locked(struct ttm_buffer_object *bo,
> > struct ttm_mem_reg *mem);
>
>
>
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