On 16/03/2022 14:39, Christian König wrote:
Am 16.03.22 um 15:26 schrieb Robert Beckett:
[SNIP]
this is where I replace an existing range check via drm_mm with the
range check I added in this patch.
Mhm, I still don't get the use case from the code, but I don't think it
matters any more.
I suppose we could add another drm_mm range tracker just for testing
and shadow track each allocation in the range, but that seemed like
a lot of extra infrastructure for no general runtime use.
I have no idea what you mean with that.
I meant as a potential solution to tracking allocations without a
range check, we would need to add something external. e.g. adding a
shadow drm_mm range tracker, or a bitmask across the range, or stick
objects in a list etc.
Ah! So you are trying to get access to the drm_mm inside the
ttm_range_manager and not add some additional range check function! Now
I got your use case.
well, specifically I was trying to avoid having to get access to the drm_mm.
I wanted to maintain an abstract interface at the resource manager
level, hence the rfc to ask if we could add a range check to
ttm_resource_manager_func.
I don't like the idea of code external to ttm having to poke in to the
implementation details of the manager to get it's underlying drm_mm.
would you mind explaining the rationale for removing range checks?
It seems to me like a natural fit for a memory manager
TTM manages buffer objects and resources, not address space. The
lpfn/fpfn parameter for the resource allocators are actually used as
just two independent parameters and not define any range. We just
keep the names for historical reasons.
The only places we still use and compare them as ranges are
ttm_resource_compat() and ttm_bo_eviction_valuable() and I already
have patches to clean up those and move them into the backend
resource handling.
except the ttm_range_manager seems to still use them as a range
specifier.
Yeah, because the range manager is the backend which handles ranges
using the drm_mm :)
If the general design going forward is to not consider ranges, how
would you recommend constructing buffers around pre-allocated regions
e.g. uefi frame buffers who's range is dictated externally?
Call ttm_bo_mem_space() with the fpfn/lpfn filled in as required. See
function amdgpu_bo_create_kernel_at() for an example.
ah, I see, thanks.
To allow similar code to before, which was conceptually just trying to
see if a range was currently free, would you be okay with a new
ttm_bo_mem_try_space, which does not do the force to evict, but instead
returns -EBUSY?
If so, the test can try to alloc, and immediately free if successful
which would imply it was free.
Regards,
Christian.
Regards,
Christian.
Regards,
Christian.
Signed-off-by: Robert Beckett <bob.beckett@xxxxxxxxxxxxx>
---
drivers/gpu/drm/ttm/ttm_range_manager.c | 21 +++++++++++++++++++++
include/drm/ttm/ttm_range_manager.h | 3 +++
2 files changed, 24 insertions(+)
diff --git a/drivers/gpu/drm/ttm/ttm_range_manager.c
b/drivers/gpu/drm/ttm/ttm_range_manager.c
index 8cd4f3fb9f79..5662627bb933 100644
--- a/drivers/gpu/drm/ttm/ttm_range_manager.c
+++ b/drivers/gpu/drm/ttm/ttm_range_manager.c
@@ -206,3 +206,24 @@ int ttm_range_man_fini_nocheck(struct
ttm_device *bdev,
return 0;
}
EXPORT_SYMBOL(ttm_range_man_fini_nocheck);
+
+/**
+ * ttm_range_man_range_busy - Check whether anything is allocated
with a range
+ *
+ * @man: memory manager to check
+ * @fpfn: first page number to check
+ * @lpfn: last page number to check
+ *
+ * Return: true if anything allocated within the range, false
otherwise.
+ */
+bool ttm_range_man_range_busy(struct ttm_resource_manager *man,
+ unsigned fpfn, unsigned lpfn)
+{
+ struct ttm_range_manager *rman = to_range_manager(man);
+ struct drm_mm *mm = &rman->mm;
+
+ if (__drm_mm_interval_first(mm, PFN_PHYS(fpfn), PFN_PHYS(lpfn
+ 1) - 1))
+ return true;
+ return false;
+}
+EXPORT_SYMBOL(ttm_range_man_range_busy);
diff --git a/include/drm/ttm/ttm_range_manager.h
b/include/drm/ttm/ttm_range_manager.h
index 7963b957e9ef..86794a3f9101 100644
--- a/include/drm/ttm/ttm_range_manager.h
+++ b/include/drm/ttm/ttm_range_manager.h
@@ -53,4 +53,7 @@ static __always_inline int
ttm_range_man_fini(struct ttm_device *bdev,
BUILD_BUG_ON(__builtin_constant_p(type) && type >=
TTM_NUM_MEM_TYPES);
return ttm_range_man_fini_nocheck(bdev, type);
}
+
+bool ttm_range_man_range_busy(struct ttm_resource_manager *man,
+ unsigned fpfn, unsigned lpfn);
#endif
