On 20 February 2015 at 23:10, Kudryavtsev, Andrey O <andrey.o.kudryavtsev@xxxxxxxxx> wrote: > I’m running NVMe SSD benchmarks which are using multi-job configurations in the most common scenarios. > I have noticed that since 2.2.5 release FIO has 3-4 times higher CPU utilization on the same workload, same system, same kernel 3.18. > In fact I’m not able to achieve 450k IOPS on latest Core-i7 CPU due to 100% utilization. > I tracked down the changes back, 2.1.14 is the most stable for me. Release had 2.2.0 the reporting issues, which were fixed in 2.2.5 but introduced high CPU utilization instead. > Did anyone notice that too? Where is the CPU usage going - userspace, device interrupts etc? If it's vanishing into userspace does gtod_reduce=1 make any difference? Does iostat confirm that you were getting more IOPs with the older fio? What's the maximum number of requests reported by /sys/block/<blockdevice>/queue/nr_requests ? (PS buffered=0 and direct=1 are synonyms of each other and why runtime=0?) -- Sitsofe | http://sucs.org/~sits/ -- 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
