fio on Intel SSD 750 (400GB)

# lspci 
00:00.0 Host bridge: Intel Corporation Sky Lake Host Bridge/DRAM Registers (rev 07)
00:01.0 PCI bridge: Intel Corporation Sky Lake PCIe Controller (x16) (rev 07)
00:02.0 VGA compatible controller: Intel Corporation Sky Lake Integrated Graphics (rev 06)
00:14.0 USB controller: Intel Corporation Sunrise Point-H USB 3.0 xHCI Controller (rev 31)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-H Thermal subsystem (rev 31)
00:16.0 Communication controller: Intel Corporation Sunrise Point-H CSME HECI #1 (rev 31)
00:17.0 SATA controller: Intel Corporation Device a102 (rev 31)
00:1b.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Root Port #19 (rev f1)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #3 (rev f1)
00:1c.4 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #5 (rev f1)
00:1d.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #9 (rev f1)
00:1d.4 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #13 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point-H LPC Controller (rev 31)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-H PMC (rev 31)
00:1f.3 Audio device: Intel Corporation Sunrise Point-H HD Audio (rev 31)
00:1f.4 SMBus: Intel Corporation Sunrise Point-H SMBus (rev 31)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (2) I219-V (rev 31)
01:00.0 Non-Volatile memory controller: Intel Corporation PCIe Data Center SSD (rev 01)
02:00.0 PCI bridge: ASMedia Technology Inc. ASM1083/1085 PCIe to PCI Bridge (rev 04)
05:00.0 Multimedia controller: Altera Corporation Device 4c15 (rev 01)
# lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    1
Core(s) per socket:    4
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 94
Model name:            Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz
Stepping:              3
CPU MHz:               3584.250
BogoMIPS:              6381.15
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              6144K
NUMA node0 CPU(s):     0-3
# uname -r
3.10.0-327.4.4.el7.x86_64
# fio -rw=randwrite -bs=4k -size=100m -directory=/mnt/ -direct=1 -numjobs=50 -name=file1 -ioengine=libaio -group_reporting
file1: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=1
...
fio-2.2.8
Starting 50 processes
Jobs: 47 (f=47): [w(1),_(1),w(5),_(1),w(41),_(1)] [100.0% done] [0KB/924.3MB/0KB /s] [0/237K/0 iops] [eta 00m:00s]
file1: (groupid=0, jobs=50): err= 0: pid=21073: Mon Jan 25 20:49:16 2016
  write: io=5000.0MB, bw=919705KB/s, iops=229926, runt=  5567msec
    slat (usec): min=1, max=80, avg= 3.66, stdev= 2.57
    clat (usec): min=0, max=13966, avg=203.23, stdev=389.81
     lat (usec): min=9, max=13969, avg=206.93, stdev=389.78
    clat percentiles (usec):
     |  1.00th=[    9],  5.00th=[   13], 10.00th=[   16], 20.00th=[   25],
     | 30.00th=[   38], 40.00th=[   65], 50.00th=[  112], 60.00th=[  145],
     | 70.00th=[  171], 80.00th=[  207], 90.00th=[  390], 95.00th=[ 1080],
     | 99.00th=[ 1592], 99.50th=[ 1672], 99.90th=[ 1944], 99.95th=[ 6112],
     | 99.99th=[11328]
    bw (KB  /s): min=15272, max=30728, per=2.07%, avg=19070.28, stdev=2008.08
    lat (usec) : 2=0.01%, 4=0.01%, 10=1.39%, 20=12.20%, 50=21.62%
    lat (usec) : 100=12.07%, 250=37.86%, 500=6.17%, 750=2.00%, 1000=1.27%
    lat (msec) : 2=5.33%, 4=0.03%, 10=0.04%, 20=0.03%
  cpu          : usr=0.83%, sys=2.40%, ctx=1279968, majf=0, minf=1417
  IO depths    : 1=100.0%, 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=0/w=1280000/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):
  WRITE: io=5000.0MB, aggrb=919705KB/s, minb=919705KB/s, maxb=919705KB/s, mint=5567msec, maxt=5567msec

Disk stats (read/write):
    dm-0: ios=0/1252806, merge=0/0, ticks=0/236240, in_queue=243278, util=98.78%, aggrios=0/1280005, aggrmerge=0/0, aggrticks=0/239884, aggrin_queue=243983, aggrutil=98.18%
  nvme0n1: ios=0/1280005, merge=0/0, ticks=0/239884, in_queue=243983, util=98.18%