protonscr

Steam repeatedly re-queues the same Vulkan shader depot after successful download and replay on NVIDIA

steamopen
ValveSoftware/steam-for-linux#13785 · opened 2026-10-21 by SammMartins · updated 2026-10-21 · 0 comments · github
SSammMartins 2026-10-21 github

System information

  • Distribution: Omarchy Linux (Arch-based)
  • Steam installation: Native package
  • Steam version: 1.0.0.87-3
  • GPU: NVIDIA GeForce GTX 1060 6 GB
  • NVIDIA driver: 580.178.04
  • Game: X4: Foundations (AppID 392160)
  • Steam library: /data/SteamLibrary
  • Filesystem: Btrfs, persistent and writable
  • Shader pre-caching: Enabled
  • Background Vulkan shader processing: Enabled

Problem description

Steam repeatedly downloads approximately 2.7–3.0 GB of shader data for X4: Foundations and processes Vulkan shaders again, even when the existing cache is present.

The issue is reproducible without rebooting the system. Steam successfully downloads and commits a shader depot, then removes a native pipeline cache file during its replay step and queues the same depot manifest again.

This causes repeated network traffic and unnecessary shader processing.

Steps to reproduce

  1. Start Steam with shader pre-caching enabled.
  2. Allow the X4: Foundations shader depot download and processing to complete.
  3. Observe the subsequent shader cache replay and merge operations in shader_log.txt.
  4. Observe Steam queueing the same shader depot manifest again.
  5. Repeat without rebooting the system.

Expected behavior

Once a shader depot has been downloaded and committed successfully, Steam should retain and reuse the valid cache data. It should not repeatedly download the identical depot unless the manifest changes or a legitimate cache invalidation occurs.

Actual behavior

Steam repeatedly queues the same shader depot manifest after completing its download and replay operations.

Relevant evidence from shader_log.txt:

  • AppID: 392160
  • Shader depot manifest: 8760948818145062529
  • Depot size: 3,035,128,149 bytes
  • At 2026-10-20 22:16:34, Steam completed the download/commit operation.
  • At 22:16:36, after the replay step removed steam_pipeline_cache.foz, Steam queued the identical manifest again.
  • The same manifest was queued again at 22:18:01, after X4 exited.

The shader cache already exists at:

/data/SteamLibrary/steamapps/shadercache/392160

It occupies approximately 6.1 GB and contains fozpipelinesv6, nvidiav1, DXVK_state_cache, downloads, and temp.

Troubleshooting already performed

  • Verified that /data is persistent and writable.
  • Verified shader cache ownership and ACLs.
  • Confirmed that the game installation is not being downloaded again.
  • Confirmed that Steam shader pre-caching remains enabled.
  • Checked for startup scripts and configuration overrides that could explain the behavior.
  • Recorded the Steam client and NVIDIA driver versions.
  • Reproduced the repeated manifest queueing without rebooting.

No game manifests or cache files were manually modified or deleted. Global shader pre-caching has not been disabled.

RegisterShader responses containing Busy (10) were observed, but the repeated manifest queueing also occurs independently of those messages.

Related reports

The behavior may be related to existing NVIDIA shader cache merge/replay issues, but the repeated queuing of the same depot manifest is the specific behavior I would like to investigate.

Questions

  1. Why does Steam queue the same committed shader depot manifest again immediately after replay?
  2. Is the removal of steam_pipeline_cache.foz expected during this operation?
  3. Could a cache-manager state or manifest-tracking issue cause Steam to repeatedly download the same depot?
  4. What additional logs or diagnostics would help identify the root cause?

I can provide relevant log excerpts and additional diagnostic information if needed.

Related threads

Upstream links