> Regarding iodepth, I am using 1 job with 1 outstanding IO - as stated in the > specification - > to circumvent IO scheduler influences. I thought higher queue depths will > always lead to > higher latencies, correct? > (https://www.kernel.org/doc/Documentation/block/stat.txt) > Therefore testing with 1 nj/1 iod will generate comparable latency results, > or not?
In the report you have mentioned IO Depth of 16. Do you mean you set 16 for Throughput and IOPS test and then reduce the Depth to 1 for latency test ? While your statement about the impact of queue depth on the latency is make sense to me, it is hard to make a connection between IOPS numbers generated with IO Depth of 16 to Latency numbers generated with IO Depth 1. > Another question, is there a chance to turn off this cache? > It seems it is not the regular device write cache, as I turned it off with > "hdparm -W" > and latencies seem to produce the same results (just on a quick test). I believe it is vendor specific, mostly drives don't honor such a requests or even cache flush requests. -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
