FEX 2609 Released With Speedier JIT Performance, JIT Disk Cache Option

FEX 2609 was released overnight as the newest monthly feature release for this open-source emulator that allows running Linux x86_64 binaries on AArch64, including the likes of Steam and Steam Play (Proton) for enabling Windows games to run rather well on ARM64 Linux systems.

FEX 2609 features a lot of work on its just-in-time (JIT) compilation support, including for better performance that may be seen in Geekbench and some games. The release announcement teased up to "2x perf uplift" at least for some nice scenarios:

"There was an optimization for the PMULHRSW instruction family that increased some Geekbench benchmark numbers. Surely some game uses it somewhere to notice the 2x perf uplift. We also made the “full” self-modifying-code detection faster, which is used for Unity games in some instances. So that’s nice. We also reduced some lock-contention in the JIT so multiple threads jitting code at the same time should block each other less frequently."

The other exciting aspect of FEX 2609 is introducing an on-disk cache for the JIT. When enabled via the FEX_DISKCACHE=1 environment variable or JSON configuration option, the compiled JIT code will be cached to disk for subsequent loads. This can help reduce the FEX JIT stutter when running games on later loads and similar. Currently though the JIT doesn't have any caching size limits or other safeguards but those will likely come in the future.

FEX also rolled out a revised logo for the open-source project:

Those wanting to learn more about today's FEX 2609 release can do so at FEX-Emu.com.