I think this is an fio bug. Description: When specifying ramp_time, cpu may show over 100% (when using a polling mode driver). If ramp_time is not specified, cpu values appear to be correct. You normally don't see this problem because most drivers don't utilize high CPU usage. You will have to use some custom driver that does polling, for example (something like http://www.dpdk.org/). OS: Any (but tested on Linux CentOS 6.6) --------- Job file: [global] thread=1 group_reporting=1 direct=1 ioengine=libaio time_based=1 ramp_time=10 runtime=10 bs=4096 filename=/dev/polling [test] rw=read numjobs=1 iodepth=1 ------------- Fio output: test: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=1 fio-2.2.12 Starting 1 thread test: (groupid=0, jobs=1): err= 0: pid=27094: Wed Nov 25 11:23:07 2015 read : io=486652KB, bw=48660KB/s, iops=12165, runt= 10001msec slat (usec): min=0, max=16, avg= 2.15, stdev= 0.60 clat (usec): min=34, max=2323, avg=79.77, stdev=20.54 lat (usec): min=36, max=2325, avg=81.79, stdev=20.54 clat percentiles (usec): | 1.00th=[ 58], 5.00th=[ 66], 10.00th=[ 69], 20.00th=[ 73], | 30.00th=[ 74], 40.00th=[ 74], 50.00th=[ 76], 60.00th=[ 85], | 70.00th=[ 88], 80.00th=[ 89], 90.00th=[ 90], 95.00th=[ 91], | 99.00th=[ 92], 99.50th=[ 93], 99.90th=[ 94], 99.95th=[ 121], | 99.99th=[ 1048] bw (KB /s): min= 0, max=48904, per=95.03%, avg=46242.40, stdev=10885.36 lat (usec) : 50=0.92%, 100=99.01%, 250=0.05%, 500=0.01%, 750=0.01% lat (usec) : 1000=0.01% lat (msec) : 2=0.01%, 4=0.01% cpu : usr=164.11%, sys=4.55%, ctx=27, majf=0, minf=3013 IO depths : 1=163.5%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued : total=r=121663/w=0/d=0, short=r=0/w=0/d=0, drop=r=0/w=0/d=0 latency : target=0, window=0, percentile=100.00%, depth=1 Run status group 0 (all jobs): READ: io=486652KB, aggrb=48660KB/s, minb=48660KB/s, maxb=48660KB/s, mint=1000 1msec, maxt=10001msec -- 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
