Kernel cache

Kernel cache#

MIOpen caches binary kernels to disk so they don’t need to be compiled the next time you run the application. This cache is stored in $HOME/.cache/miopen by default, but you can change this at build time by setting the MIOPEN_CACHE_DIR CMake variable.

Clear the cache#

You can clear the cache by deleting the cache directory (for example, $HOME/.cache/miopen). However, you should only do this for development purposes or to free disk space. You don’t need to clear the cache when upgrading MIOpen.

Disabling the cache#

Disabling the cache is generally useful for development purposes. You can disable the cache in this following situations:

  • During the build, either set MIOPEN_CACHE_DIR to an empty string or set BUILD_DEV=ON when configuring CMake.

  • At runtime, set the MIOPEN_DISABLE_CACHE environment variable to true.

Updating MIOpen and removing the cache#

For MIOpen version 2.4 and later, MIOpen’s kernel cache directory is versioned, so any existing cached kernels won’t collide when upgrading.

Note

For MIOpen version 2.3 and earlier, if the compiler changes or you modify the kernels, then you must delete the cache for the existing MIOpen version using the command rm -rf $HOME/.cache/miopen/<miopen-version-number>.

Installing precompiled kernels#

GPU architecture-specific, precompiled kernel packages are available in the ROCm package repositories. These packages reduce the startup latency of MIOpen kernels. They contain a kernel cache file, which they install in the ROCm installation directory along with other MIOpen artifacts. When MIOpen launches a kernel, it first checks for a kernel in the kernel cache within the MIOpen installation directory. If the file doesn’t exist, or the required kernel isn’t found, it compiles the kernel and places it in the kernel cache.

These packages are optional and must be separately installed from MIOpen. To conserve disk space, you can choose not to install these packages (which would result in higher startup latency). You also have the option to only install kernel packages for your device architecture, which helps save disk space.

If the MIOpen kernels package is not installed, or if the kernel doesn’t match the GPU, you’ll get a warning message similar to:

> MIOpen(HIP): Warning [SQLiteBase] Missing system database file:gfx906_60.kdb Performance may degrade

The performance degradation mentioned in the warning only affects the network start-up time (the “initial iteration time”) and can be safely ignored.

Refer to the installation instructions for guidance on installing the MIOpen kernels package.