Okaaay, thanks, after disabling it the latency difference between krbd and librbd slightly dropped, now it is like 0.57ms (krbd) vs 0.63ms (librbd) in my setup. It's becoming not bad overall since I'm approaching 0.5ms latency... :)
Forgot to mention that these numbers are from running fio on the same server. From the other one the numbers become 0.6ms (krbd) vs 0.67ms (librbd), which puts me slightly farther away from my goal of 0.5ms latency :)
-- With best regards, Vitaliy Filippov
