Dm-Writecache
Linux Device Mapper WriteCache (dm-writecache) performance improvements in Linux Kernel 5.8
The Linux ‘dm-writecache’ target allows for writeback caching of newly written data to an SSD or NVMe using persistent memory will achieve much better performance in Linux Kernel 5.8.
Red Hat developer Mikulas Patocka has been working to enhance the dm-writecache performance using Intel Optane Persistent Memory (PMem) as the cache device.
The performance optimization now queued for Linux 5.8 is making use of CLFLUSHOPT within dm-writecache when available instead of MOVNTI. CLFLUSHOPT is one of Intel’s persistent memory instructions that allows for optimized flushing of cache lines by supporting greater concurrency. The CLFLUSHOPT instruction has been supported on Intel servers since Skylake and on AMD since Zen.
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