Exactly. Q=32 Random 4k IOP reads are much, much faster than a queue depth of 1 on SSDs. On regular hard drives you might see a 200% speedup with a high queue depth, on SSDs you could see 1000-3000% speedup.
SSDs live off their internal parallelism, if you aren't using a Queue>16 you are not making real use of an SSD. Q=32 or even Q=64 are usually the right settings.
It all depends though if you want throughput or latency. If you really really care about latency you should balance the queue depth and probably use it between 16 and 32. The reason is that with higher queues you get more collisions on the same die and then latency suffers. There are read-read, write-read, erase-write and all the other combinations but those three are the interesting ones.
pixl97|11 years ago
baruch|11 years ago
It all depends though if you want throughput or latency. If you really really care about latency you should balance the queue depth and probably use it between 16 and 32. The reason is that with higher queues you get more collisions on the same die and then latency suffers. There are read-read, write-read, erase-write and all the other combinations but those three are the interesting ones.