Modern data center dGPUs are usually equipped with very large VRAM. On server with such dGPUs(192GB VRAM * 8) and 2TB system memory, hibernate will fail due to no enough free memory.
The root cause is that during hibernation all VRAM memory get evicted to GTT or shmem. In both case, it is in system memory and kernel will try to copy the pages to hibernation image. In the worst case, this causes 2 copies of VRAM memory in system memory, 2TB is not enough for the hibernation image. 192GB * 8 * 2 = 3TB > 2TB. The fix includes following changes. With these changes, there's much less pages needed to be copied to hibernate image and hibernation can succeed. * patch 1 and 2: move GTT to shmem after evicting VRAM. so that the GTT pages can be freed. * patch 3: force write shmem pages to swap disk and free shmem pages. After swapout GTT to shmem in hibernation prepare stage, the GPU will be resumed again in thaw stage. The swapin and restore BOs of resume takes lots of time (50 mintues observed for 8 dGPUs). And it's unnecessary since writing hibernation image do not need GPU for hibernate successful case. * patch 4 and 5: skip resume of device in thaw stage for successful hibernation case to reduce the hibernation time. v2: * split first patch to 2 patches, 1 for ttm, 1 for amdgpu * refined the new ttm api * add more comments for shrink_shmem_memory() and its callsite * export variable pm_transition in kernel * skip resume in thaw() for successful hibernation case v3: * refined ttm_device_prepare_hibernation() to accept device argument * use guard(mutex) to replace mutex_lock and mutex_unlock * move ttm_device_prepare_hibernation call to amdgpu_device_evict_resources() * add pm_transition_event(), instead of exporting pm_transition variable * refined amdgpu_pmops_thaw(), use switch-case for more clarity Samuel Zhang (5): 1. drm/ttm: add ttm_device_prepare_hibernation() api 2. drm/amdgpu: move GTT to shmem after eviction for hibernation 3. PM: hibernate: shrink shmem pages after dev_pm_ops.prepare() 4. PM: hibernate: add new api pm_transition_event() 5. drm/amdgpu: do not resume device in thaw for normal hibernation drivers/base/power/main.c | 5 +++++ drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 10 ++++++++- drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 15 ++++++++++++- drivers/gpu/drm/ttm/ttm_device.c | 23 +++++++++++++++++++ include/drm/ttm/ttm_device.h | 1 + include/linux/pm.h | 16 +++++++++++++ kernel/power/hibernate.c | 26 ++++++++++++++++++++++ 7 files changed, 94 insertions(+), 2 deletions(-) -- 2.43.5
