Hi Audrey,  which plugin are you running? examples/nvme/fio_plugin/fio_plugin or examples/bdev/fio_plugin/fio_plugin ? Is it on Fedora or Centos?

Isaac
From: SPDK [mailto:spdk-bounces(a)lists.01.org] On Behalf Of Andrey Kuzmin
Sent: Monday, December 18, 2017 5:59 AM
To: Storage Performance Development Kit <spdk(a)lists.01.org>
Subject: Re: [SPDK] SPDK FIO poor 4K read performance


On Mon, Dec 18, 2017, 16:08 Mayank <mayank.patel(a)mayadata.io<mailto:mayank.patel(a)mayadata.io>> wrote:

Hi All,

I have performed fio benchmark test with SPDK fio plugin for throughput test with iodepth = 32 and numjobs=4.

Latency results are as below:


rand read

11.2k

45.9MB/s

88.83 usec

rand write

126k

518MB/s

7.56 usec


Throughput results are as below:

Throughput (io:32 thr:4)

IOPS

Throuhgput

Latency (usec)

seq read

406k

1665MB/s

314.71

seq write

455k

1865MB/s

280.87

rand read

478k

1959MB/s

267.29

rand write

442k

1812MB/s

289.03



In results, 'm getting sequential read IOPS lesser than sequential write IOPS.

I am using NVME model number : INTEL SSDPEDMD020T4.
kernel  : 4.13.13
fio version : 2.21

BTW, your fio version is couple of years behind.

can anybody tell me what could be the issue?

The latency data above clearly shows the reason: writes are being handled by the internal SSD cache of few usec latency, while reads are served off the real media, with typical (high-end) SSD latency of about 100 usec.

Regards,
Andrey


Thanks,
Mayank

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Regards,
Andrey