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* There is one thing that decreases latency 2-3 times at once. It’s disabling all power-save functions of CPUs:
** <tt>cpupower idle-set -D 1</tt> — this disables C-States (or you can pass <tt>processor.max_cstate=1 intel_idle.max_cstate=0</tt> to the kernel command-line)
** <tt>cpupower frequency-set -g performance</tt> or (for older versions) <tt>for i in $(seq 0 $((`nproc`-1))); do cpufreq-set -c $i -g performance; done</tt> — this disables frequency scaling.
* When power-save is disabled CPU heats up as a GTX, but you get 2-3 times more iops.
* High CPU requirement is one of the arguments to NOT use Ceph in a «hyperconverged setup», the setup in which storage and compute nodes are combined.
