Question about the performance gain

[DarthVaderSCY]

Thank you for your opening source code! But when I test readrandom with your pmem secondary cache against without, they are exactly the same when --use_direct_reads=true, and with scache is 2/3 slower than without when --use_direct_reads=false. I wonder how your tests result were and if you have implemented newer version of this plugin. Hope for your replying!