Am 17.10.2017 um 10:15 schrieb Chunming Zhou:


On 2017年10月17日 15:46, Christian König wrote:
Am 17.10.2017 um 06:11 schrieb Chunming Zhou:


On 2017年10月16日 19:40, Christian König wrote:
Am 16.10.2017 um 11:42 schrieb Chunming Zhou:


On 2017年10月16日 17:26, Christian König wrote:
From: Christian König <christian.koe...@amd.com>

While binding BOs to GART we need to allow a bit overcommit in the GTT
domain.
If allowing overcommit, will the new node not over the GART mc range? Which is also allowed?
No that is checked separately by drm_mm_insert_node_in_range().

This is just to cover the case when we have a BO in GTT space which needs to be bound into the GART table.
Sorry, I missed that even gart BO is also without node during creating.
One nitpick, atomic64_sub(mem->num_pages, &mgr->available) will be calculated twice for one gart bo create and pin, which results in available isn't correct.

Yeah, that is true but not as problematic as you think.

The BO is transfered from the old mem object (without GART mapping) to the new mem object (with GART mapping). While doing this the old mem object is released, so we actually don't leak the memory.

It's just that for a moment the BO is accounted twice, once for the old location and once for the new one.
If in memory pressure, I think we could allocate memory over the mgr limitation.

For example, the limitation is 1024M, the BO allocation is 800M, when the second counting, the available will be -576M,

Yes, correct so far. That's why I've added the extra check in amdgpu_gtt_mgr_usage().

since available is unsigned

available is an atomic64_t and that is signed IIRC.

We could cast mem->num_pages to signed as well to be double sure, but as far as I can see that should work.

Regards,
Christian.


Regards,
David Zhou

But we had that behavior previously as well, so that is not something introduced with this patch.

Regards,
Christian.


Regards,
David Zhou

Regards,
Christian.


Regards,
David Zhou
Otherwise we can never use the full GART space when GART size=GTT size.

Signed-off-by: Christian König <christian.koe...@amd.com>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c | 8 +++++---
  1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
index 0d15eb7d31d7..33535d347734 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
@@ -169,7 +169,8 @@ static int amdgpu_gtt_mgr_new(struct ttm_mem_type_manager *man,
      int r;
        spin_lock(&mgr->lock);
-    if (atomic64_read(&mgr->available) < mem->num_pages) {
+    if ((&tbo->mem == mem || tbo->mem.mem_type != TTM_PL_TT) &&
+        atomic64_read(&mgr->available) < mem->num_pages) {
          spin_unlock(&mgr->lock);
          return 0;
      }
@@ -244,8 +245,9 @@ static void amdgpu_gtt_mgr_del(struct ttm_mem_type_manager *man,
  uint64_t amdgpu_gtt_mgr_usage(struct ttm_mem_type_manager *man)
  {
      struct amdgpu_gtt_mgr *mgr = man->priv;
+    s64 result = man->size - atomic64_read(&mgr->available);
- return (u64)(man->size - atomic64_read(&mgr->available)) * PAGE_SIZE;
+    return (result > 0 ? result : 0) * PAGE_SIZE;
  }
    /**
@@ -265,7 +267,7 @@ static void amdgpu_gtt_mgr_debug(struct ttm_mem_type_manager *man,
      drm_mm_print(&mgr->mm, printer);
      spin_unlock(&mgr->lock);
- drm_printf(printer, "man size:%llu pages, gtt available:%llu pages, usage:%lluMB\n", + drm_printf(printer, "man size:%llu pages, gtt available:%lld pages, usage:%lluMB\n",
             man->size, (u64)atomic64_read(&mgr->available),
             amdgpu_gtt_mgr_usage(man) >> 20);
  }






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