Test the IOPS performance of an ESSD

Test conditions:

• Sample operation: random write (randwrite).
• Image: We recommend that you use a later version of a Linux public image provided by Alibaba Cloud, such as CentOS 7.4 64-bit, CentOS 7.3 64-bit, CentOS 7.2 64-bit, or Alibaba Cloud Linux 2.1903 64-bit.
• Tool: We recommend that you use fio.
• Instance type: We recommend that you use ecs.g5se.18xlarge.
• ESSD: We recommend that you use a PL3 ESSD. In this example, the device name of the ESSD is /dev/your_device. Replace it with your actual device name. For more information, see ESSDs.
  Warning

  • You can obtain accurate test results by testing raw disk partitions. However, you may destroy the file system structure in a raw disk partition if you directly test the partition. Before you test a raw disk, we recommend that you create a snapshot of the disk to back up your data. For more information about how to create a snapshot, see Create a snapshot for a disk.
  • We recommend that you do not test a disk where the operating system is located or a disk that stores important data. To prevent data loss, we recommend that you use a new Elastic Compute Service (ECS) instance that contains no data for the test.

Procedure

1. Remotely connect to an ECS instance. For more information, see Connect to a Linux instance by using password authentication.
2. Run the following commands in sequence to install libaio and fio:

   sudo yum install libaio -y
   sudo yum install libaio-devel -y
   sudo yum install fio -y

3. Switch the directory.

   cd /tmp

4. Create the test100w.sh script.

   vim test100w.sh

5. Paste the following content to the test100w.sh script:

   function RunFio
   {
    numjobs=$1   # The number of test threads. In this example, the value is 10.
    iodepth=$2   # The maximum number of concurrent I/O requests. In this example, the value is 64.
    bs=$3        # The size of the data block per I/O. In this example, the value is 4k.
    rw=$4        # The read and write policy. In this example, the value is randwrite.
    filename=$5  # The name of the file to be tested. In this example, the value is /dev/your_device.
    nr_cpus=`cat /proc/cpuinfo |grep "processor" |wc -l`
    if [ $nr_cpus -lt $numjobs ];then
        echo "Numjobs is more than cpu cores, exit!"
        exit -1
    fi
    let nu=$numjobs+1
    cpulist=""
    for ((i=1;i<10;i++))
    do
        list=`cat /sys/block/your_device/mq/*/cpu_list | awk '{if(i<=NF) print $i;}' i="$i" | tr -d ',' | tr '\n' ','`
        if [ -z $list ];then
            break
        fi
        cpulist=${cpulist}${list}
    done
    spincpu=`echo $cpulist | cut -d ',' -f 2-${nu}`
    echo $spincpu
    fio --ioengine=libaio --runtime=30s --numjobs=${numjobs} --iodepth=${iodepth} --bs=${bs} --rw=${rw} --filename=${filename} --time_based=1 --direct=1 --name=test --group_reporting --cpus_allowed=$spincpu --cpus_allowed_policy=split
   }
   echo 2 > /sys/block/your_device/queue/rq_affinity
   sleep 5
   RunFio 10 64 4k randwrite /dev/your_device

6. Modify the parameter settings in the test100w.sh script based on your actual environment.
   • Replace your_device with the actual device name of the ESSD.
   • Modify 10, 64, 4k, randwrite, and /dev/your_device in RunFio 10 64 4k randwrite /dev/your_device.
   • If you want to proceed with this operation, set filename to a device name such as [/dev/vdb]. If you do not want to risk data loss, set filename to a file path such as [/mnt/test.image].

   Warning

   • You can obtain accurate test results by testing raw disk partitions. However, you may destroy the file system structure in a raw disk partition if you directly test the partition. Before you test a raw disk, we recommend that you create a snapshot of the disk to back up your data. For more information about how to create a snapshot, see Create a snapshot for a disk.
   • We recommend that you do not test a disk where the operating system is located or a disk that stores important data. To prevent data loss, we recommend that you use a new Elastic Compute Service (ECS) instance that contains no data for the test.
7. Test the performance of the ESSD.

   sh test100w.sh

   If the IOPS=*** result appears, the performance stress test for the ESSD is complete.

Details about the test100w.sh script

• In the script, the following command sets the rq_affinity parameter to 2:

  echo 2 > /sys/block/your_device/queue/rq_affinity

  Value of rq_affinity	Description
  1	Indicates that the block device delivers the received I/O completion event to the group of vCPUs that submit the corresponding I/O requests. In scenarios where multiple threads concurrently run, the I/O completion event may be delivered only to one vCPU and cause a performance bottleneck.
  2	Indicates that the block device delivers the received I/O completion event to the vCPU that submits the corresponding I/O requests. In scenarios where multiple threads concurrently run, each vCPU can deliver its maximum performance.

• The following command runs jobs to bind queues to different CPU cores:

  fio -ioengine=libaio -runtime=30s -numjobs=${numjobs} -iodepth=${iodepth} -bs=${bs} -rw=${rw} -filename=${filename} -time_based=1 -direct=1 -name=test -group_reporting -cpus_allowed=$spincpu -cpus_allowed_policy=split

  Note In normal mode, a device has a single request queue. This request queue becomes a performance bottleneck when multiple threads concurrently run to process I/O. In multi-queue mode, a device can have multiple request queues to process I/O and deliver the maximum backend storage performance. For example, you have four I/O threads. To make full use of the multi-queue mode and improve storage performance, you must bind these threads to the CPU cores that correspond to different request queues.

  Parameter	Description	Example
  numjobs	The number of I/O threads.	10
  /dev/your_device	The device name of the ESSD.	/dev/vdb
  cpus_allowed_policy	The parameter provided by fio to bind vCPUs. fio provides the cpus_allowed_policy and cpus_allowed parameters to bind vCPUs.	split

  The preceding command runs jobs to bind queues to different CPU cores. These queues have different queue IDs. To view the ID of the CPU core to which a queue is bound, perform the following steps:

  • Run the ls /sys/block/your_device/mq/ command. In this command, your_device is your device name. Example: vdb. This command returns the ID of the queue for an ESSD whose device name is in the /dev/vd* format.
  • Run the cat /sys/block/your_device/mq//cpu_list command. In this command, your_device is your device name. Example: vdb. This command returns the ID of the CPU core to which the queue for an ESSD is bound. The device name of the ESSD is in the /dev/vd* format.