Test the IOPS performance of an enhanced SSD

Procedure

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

   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 code to the test100w.sh script.

   function RunFio
   {
    numjobs=$1   # The number of the threads to be tested. 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/vdb.
    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/vdb/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/vdb/queue/rq_affinity
   sleep 5
   RunFio 10 64 4k randwrite /dev/vdb

6. You need to modify the parameter settings in the test100w.sh script based on your environment.
   • Set vdb to the actual device name of the enhanced SSD.
   • Modify 10, 64, 4k, randwrite, and /dev/vdb in RunFio 10 64 4k randwrite /dev/vdb.
   • If you choose 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].
7. Test the performance of the enhanced SSD.

   sh test100w.sh

   When the IOPS=*** appears, it indicates that the performance test of the enhanced SSD is completed.

Details of the test100w.sh script

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

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

  Value of rq_affinity	Description
  1	Indicates that the block device forwards the received I/O Completion events to the vCPU group that submits the corresponding I/O requests. When multiple threads concurrently process I/O requests, the I/O Completion events may run on the same vCPU, which results in a performance bottleneck.
  2	Indicates that the block device forwards the received I/O Completion events to the vCPU that submits the corresponding I/O requests. The performance of each vCPU is fully delivered when multiple threads concurrently process I/O requests.

• The following command attaches jobs 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 Typically, a device has only one request queue. This unique request queue becomes a performance bottleneck when multiple threads concurrently process I/O requests. In Multi-Queue mode, one device can have multiple request queues that process I/O requests, delivering full performance of the backend storage service. If you have four I/O threads, you must attach them to the CPU cores that correspond to different request queues. This allows you to leverage the full capabilities of the Multi-Queue mode to improve storage performance.

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

  The preceding command runs multiple jobs that are bound to different CPU cores and correspond to different queue IDs. To view the value of cpu_core_id that is bound to a queue ID, perform the following steps:

  • Run the ls /sys/block/vd*/mq/ command to view the queue ID of the enhanced SSD whose device name is in /dev/vd* format.
  • Run the cat /sys/block/vd*/mq//cpu_list command to view the cpu_core_id corresponding to the queue ID of the enhanced SSD whose device name is in /dev/vd* format.