On 2019-04-29 8:34 a.m., Christian König wrote: > Am 28.04.19 um 09:44 schrieb Kuehling, Felix: >> From: Kent Russell <kent.russell@xxxxxxx> >> >> GTT size is currently limited to the minimum of VRAM size or 3/4 of >> system memory. This severely limits the quanitity of system memory >> that can be used by ROCm application. >> >> Increase GTT size to the maximum of VRAM size or system memory size. > > Well, NAK. > > This limit was done on purpose because we otherwise the > max-texture-size would be crashing the system because the OOM killer > would be causing a system panic. > > Using more than 75% of system memory by the GPU at the same time makes > the system unstable and so we can't allow that by default. Like we discussed, the current implementation is too limiting. On a Fiji system with 4GB VRAM and 32GB system memory, it limits system memory allocations to 4GB. I think this workaround was fixed once before and reverted because it broke a CZ system with 1GB system memory. So I suspect that this is an issue affecting small memory systems where maybe the 1/2 system memory limit in TTM isn't sufficient to protect from OOM panics. The OOM killer problem is a more general problem that potentially affects other drivers too. Keeping this GTT limit broken in AMDGPU is an inadequate workaround at best. I'd like to look for a better solution, probably some adjustment of the TTM system memory limits on systems with small memory, to avoid OOM panics on such systems. Regards, Felix > > What could maybe work is to reduce amount of system memory by a fixed > factor, but I of hand don't see a way of fixing this in general. > > Regards, > Christian. > >> >> Signed-off-by: Kent Russell <kent.russell@xxxxxxx> >> Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx> >> Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx> >> --- >> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 9 ++++----- >> 1 file changed, 4 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c >> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c >> index c14198737dcd..e9ecc3953673 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c >> @@ -1740,11 +1740,10 @@ 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)); >> - } >> - else >> + gtt_size = max3((AMDGPU_DEFAULT_GTT_SIZE_MB << 20), >> + adev->gmc.mc_vram_size, >> + ((uint64_t)si.totalram * si.mem_unit)); >> + } else >> gtt_size = (uint64_t)amdgpu_gtt_size << 20; >> /* Initialize GTT memory pool */ > _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
