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* …but within reason as one Bluestore OSD can eat up to ~6 cores under full load.
* «Clock speed» means nominal, not Turbo Boost speed, because Turbo Boost is only beneficial for single-threaded workloads.
* CPU pinning recommendations (taskset command) are almost outdated, because Ceph OSDs are multi-threaded. At least 4 threads are active during write, so you’ll only slow your OSDs down if you allocate less than 4-6 cores for each of them.
* There are 2 parameters responsible for OSD worker thread count — osd_op_num_shards and osd_op_num_threads_per_shard…
* …But trying to tune them is pointless, default configuration (1x5 for HDDs and 2x8 for SSDs) is optimal. The problem is that all worker threads still serialize writes into a single kv_sync_thread, and the whole scheme only scales up to ~6 worker threads.