Hello I am trying to measure IOPs on a RAID system using FIO. I've been using FIO for a while and I'm pretty familiar with it. However, I have found for small blocksizes, the benchmark is CPU bound as it only works on a single CPU core. Here's what I mean. All these are sequential read results. Iometer results: 512B 181,317 1K 166,232 2K 133,753 4K 109,498 8K 78,276 16K 51,638 FIO results: 512B 97,494 1K 100,034 2K 98,615 4K 93,859 8K 83,064 16K 69,623 I can see when observing the output from "top" that the "fio" thread is at 99% for the smaller block sizes. So it appears to be CPU bound for small block sizes - 512B to 4K. >From 8K onwards FIO is actually faster than Iometer. Software: Linux 2.6.36.3 FIO 1.50 Iometer 1.1.0 Hardware: Intel Xeon X3450 @ 2.67GHz Hardware RAID6 array FIO command used: fio -name iops -rw=read -bs=512 -runtime=180 -iodepth 4 -filename /dev/storage/iometer -ioengine libaio -direct=1 As you can see I'm testing the block device directly without using a file system. I have tried different iodepth values but it makes no difference. Any ideas on how I can measure the IOPs of the RAID device when using small block sizes? I really want to use FIO as I can script it. -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
