On 1/6/21 7:52 AM, Christian König wrote:
Am 05.01.21 um 23:31 schrieb Joshua Ashton:
On 1/5/21 10:10 PM, Alex Deucher wrote:
On Tue, Jan 5, 2021 at 5:05 PM Joshua Ashton <joshua@xxxxxxxxx> wrote:
Since commit 24562523688b ("Revert "drm/amd/amdgpu: set gtt size
according to system memory size only""), the GTT size was limited by
3GiB or VRAM size.
The commit in question was to fix a hang with certain tests on APUs.
That should be tested again before we re-enable this. If it is fixed,
we should just revert the revert rather than special case dGPUs.
Alex
I think the commit before the revert (ba851eed895c) has some
fundamental problems:
It was always specifying max(3GiB, 3/4ths RAM) of GTT, even if that
wouldn't fit into say, 1GiB or 2GiB of available RAM.
Limiting GTT to min(max(3GiB, VRAM), 3/4ths RAM) size on dGPUs makes
sense also and is a sensible limit to avoid silly situations with
overallocation and potential OOM.
This patch solves both of those issues.
No, Alex is right this approach was already tried and it causes problems.
Additional to that why should this be an issue? Even when VRAM is very
small on APUs we still use 3GiB of GTT.
Regards,
Christian.
The problem is that 3GiB of GTT isn't enough for most modern games. My
laptop has a 128MiB carveout which is not possible to be configured in
the BIOS so I am stuck with that size without extra kernel parameters
which shouldn't be necessary.
If you dislike the approach of keeping the extra check for dGPUs and
limiting GTT there, then I would say that we should use
gtt_size = 3/4ths system memory
for all devices instead of
gtt_size = max(3/4ths system memory, 3GiB)
as it was before the revert, as it is problematic on systems with < 3GiB
of system memory.
- Joshie 🐸✨
- Joshie 🐸✨
This is problematic on APUs, especially with a small carveout
which can be as low as a fixed 128MiB, as there would be very a limited
3GiB available for video memory.
This obviously does not meet the demands of modern applications.
This patch makes it so the GTT size heuristic always uses 3/4ths of
the system memory size on APUs (limiting the size by 3GiB/VRAM size
only on devices with dedicated video memory).
Fixes: 24562523688b ("Revert drm/amd/amdgpu: set gtt size according to
system memory size only")
Signed-off-by: Joshua Ashton <joshua@xxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 5 +++--
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 12 +++++++++---
2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 72efd579ec5e..a5a41e9272d6 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -192,8 +192,9 @@ module_param_named(gartsize, amdgpu_gart_size,
uint, 0600);
/**
* DOC: gttsize (int)
- * Restrict the size of GTT domain in MiB for testing. The default
is -1 (It's VRAM size if 3GB < VRAM < 3/4 RAM,
- * otherwise 3/4 RAM size).
+ * Restrict the size of GTT domain in MiB for testing. The default
is -1 (On APUs this is 3/4th
+ * of the system memory; on dGPUs this is 3GiB or VRAM sized,
whichever is bigger,
+ * with an upper bound of 3/4th of system memory.
*/
MODULE_PARM_DESC(gttsize, "Size of the GTT domain in megabytes (-1
= auto)");
module_param_named(gttsize, amdgpu_gtt_size, int, 0600);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 4d8f19ab1014..294f26f4f310 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1865,9 +1865,15 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
struct sysinfo si;
si_meminfo(&si);
- gtt_size = min(max((AMDGPU_DEFAULT_GTT_SIZE_MB << 20),
- adev->gmc.mc_vram_size),
- ((uint64_t)si.totalram * si.mem_unit
* 3/4));
+ gtt_size = (uint64_t)si.totalram * si.mem_unit * 3/4;
+ /* If we have dedicated memory, limit our GTT size to
+ * 3GiB or VRAM size, whichever is bigger
+ */
+ if (!(adev->flags & AMD_IS_APU)) {
+ gtt_size =
min(max(AMDGPU_DEFAULT_GTT_SIZE_MB << 20,
+ adev->gmc.mc_vram_size),
+ gtt_size);
+ }
}
else
gtt_size = (uint64_t)amdgpu_gtt_size << 20;
--
2.30.0
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