测试从应用到DB的准确的网络延迟

最近几大云厂商把底层的基础设施包装起来后，通过Ping等很难知道真正的网络延迟了，因为通过ping还没到db都返回了，如何知道从应用到db的真正网络延迟呢？

用我的脚本

#!/bin/bash

m=
db_port=$
db_port=$
db_user=$
db_pass=$

echo "">res.txt
    t_start=`mysql -h ${db_port} -P ${db_port} -u ${db_user} -p${db_pass}  -N -e"select REPLACE(unix_timestamp(current_timestamp(3)),'.','')"`
for (( i=; i < ; i++ ))
do
    { time mysql -h ${db_port} -P ${db_port} -u ${db_user} -p${db_pass} -N -e"select 1" > /dev/null ; } >> res.txt
    let "m++"
done
    t_end=`mysql -h ${db_port} -P ${db_port} -u ${db_user} -p${db_pass} -N -e"select REPLACE(unix_timestamp(current_timestamp(3)),'.','')"`

t_diff=`expr ${t_end} - ${t_start}`
echo "execute "${t_diff}" milliseconds!"

awk -F"m" '/real/{print $2}' res.txt | awk '{sum+=$1} END {print "real_Sum=",sum/NR}'
awk -F"m" '/user/{print $2}' res.txt | awk '{sum+=$1} END {print "user_Sum=",sum/NR}'
awk -F"m" '/sys/{print $2}' res.txt | awk '{sum+=$1} END {print "sys_Sum=",sum/NR}'