user3323381's questions

QEMU emulator version 2.9.0(qemu-kvm-ev-2.9.0-16.el7_4.11.1)
Linux 3.10.0-693.el7.x86_64

There is two luns attached via virtio-scsi (vcpu=1,virtio-scsi controller queue set to 1)

Firt:

dd /dev/sde device only , the iops was 6k.

Second:

fio(num_job=3) + /dev/sdc and still dd sde

worked just fine, iops of sde still 6k.

Final:

only increase num_job of fio to 4,

then iops of sde drop to 34 !!!!????

I had no idea why,if anyone could give me some suggestions?

Firt Test:

Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
sdc               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
sde               0.00     0.00    0.00 6638.14     0.00    51.86    16.00     0.92    0.14    0.00    0.14   0.14  92.16

Second Test:

Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
sdc               0.00     0.00   99.01   76.24     0.77     0.60    15.95    96.04  547.80  969.59    0.01   5.65  99.01
sde               0.00     0.00    0.00 6966.34     0.00    54.42    16.00     0.83    0.12    0.00    0.12   0.12  82.87

Final Test:

Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
sdc               0.00     0.00  100.00  107.00     0.78     0.84    16.00   128.97  621.03 1280.22    4.97   4.83 100.00
sde               0.00     0.00    0.00   31.00     0.00     0.24    16.00     0.99   32.03    0.00   32.03  32.03  99.30

dd:

while true;do dd if=/dev/zero of=./test bs=8K count=102400 oflag=direct;done

fio.ini

[global]
    bs=8k
    ioengine=libaio
    #rw=randrw
    time_based
    runtime=7200
    direct=1
    group_reporting
    iodepth=32
    size=1G
    
    [file1]
    filename=/dev/sdc
    numjobs=3
    rw=randrw