I'm trying to figure out the completion latency of fio benchmark with NVMe SSD.
I made following fio script to test benchmark in fio.
I used following options.
rw=read, ioengine=sync, direct=1
So, I thought there's not much things to make completion times different.
However, the result wasn't what I thought.
The result is 1th : 11us to 99.99th : 111 us.
Synchronous read make no outstanding IOs, so all I/Os are processed sequentially,
And direct option can bypass the buffer in OS.
I thought most of latencies are same.
Any ideas for this result?