[原] KVM 环境下MySQL性能对比

KVM 环境下MySQL性能对比

标签（空格分隔）： Cloud2.0

[TOC]

测试目的

对比MySQL在物理机和KVM环境下性能情况

压测标准

压测遵循单一变量原则，所有的对比都是只改变一个变量的前提下完成

测试方式

以物理机MySQL为基准，分别做两次测试

1. 测试IO相关参数(writethrough, innodb flush method)
2. 测试CPU相关参数(NUMA Balancing)

测试环境

CPU:Intel(R) Xeon(R) CPU E5-2620 v2 @ 2.10GHz X 24
MEM:48G
Disk:SSD 1.3T
System:Ubuntu 14.04.4 LTS
Kernel:3.16.0-30-generic
MySQL:mysql-5.5.31-linux2.6-x86_64
Sysbench:0.4.12
KVM:QEMU emulator version 2.0.0 (Debian 2.0.0+dfsg-2ubuntu1.22)

测试变量

因相关资料说明，writethrough IO模式能够保障数据一致性，所以在MySQL环境下，默认只测试writethrough环境

以打开NUMA Balancing的物理机环境为基准，测试KVM环境如下变量:

1. writethrough cache模式下的 innodb io (O_DIRECT, O_SYNC)
2. KVM 宿主机 NUMA Balancing 对MySQL性能影响

测试软件环境

配置模板如下(只列举关键参数)

# The MySQL server
[mysqld]
default-storage-engine = innodb

# MyISAM setup
key_buffer_size = 128M
myisam_sort_buffer_size = 64M

## gloabl config
max_allowed_packet = 16M
max_heap_table_size = 64M
tmp_table_size = 8M
max_connections = 4000
open_files_limit = 6000
table_open_cache = 512
read_buffer_size = 2M
read_rnd_buffer_size = 4M
join_buffer_size = 256K
sort_buffer_size = 2M
thread_cache_size = 8
query_cache_size = 0
thread_concurrency = 16

# Replication Master setup
log-bin = mysql-bin
relay-log = mysqld-relay-bin
max_binlog_size = 100M
binlog_format = row
binlog_cache_size=32K
thread_stack=262144
auto_increment_increment = 3
auto_increment_offset = 1

# Logging
slow_query_log  = 1
long_query_time = 2

# InnoDB setup
innodb_file_format = Barracuda
innodb_file_per_table
innodb_buffer_pool_size = 4096M
innodb_log_file_size = 16M
innodb_log_buffer_size = 40M
innodb_flush_log_at_trx_commit = 2
innodb_lock_wait_timeout = 50
innodb_log_files_in_group=2
innodb_io_capacity=2000

[mysqldump]
quick
extended-insert = false
default-character-set = utf8
max_allowed_packet = 16M

[mysql]
no-auto-rehash

[myisamchk]
key_buffer_size = 8M
sort_buffer_size = 8M
read_buffer = 2M
write_buffer = 2M

[mysqlhotcopy]
interactive-timeout

KVM-qemu 配置如下:

<domain type='kvm'>
    <name>mysql1</name>
    <memory unit='MiB'>5120</memory>
    <currentMemory unit='MiB'>5120</currentMemory>
    <vcpu placement='static'>4</vcpu>
    <os>
        <type>hvm</type>
        <boot dev='hd' />
    </os>
    <features>
        <acpi />
        <apic />
        <pae />
    </features>
    <clock offset='utc' />
    <on_poweroff>destroy</on_poweroff>
    <on_reboot>restart</on_reboot>
    <on_crash>restart</on_crash>
    <devices>
        <emulator>/usr/bin/kvm-spice</emulator>
        <disk type='file' device='disk'>
            <driver name='qemu' type='qcow2' />
            <source file='/data2/kvm/image1/mysql.qcow2' />
            <target dev='vda' bus='virtio' />
        </disk>
        <disk type='file' device='disk'>
            <driver name='qemu' type='qcow2' cache='writethrough'/>
            <source file='/data2/kvm/image1/data.qcow2' />
            <target dev='vdb' bus='virtio' />
        </disk>
        <interface type='network'>
            <source network='default1' />
            <model type='virtio' />
        </interface>
        <console type='pty'>
            <target port='0' />
        </console>
        <graphics type='vnc' autoport='yes' sharePolicy='allow-exclusive' keymap='en-us'>
            <listen type='address' address='0.0.0.0' />
        </graphics>
    </devices>
</domain>

测试基准

测试以物理机的MySQL实例作为参照
物理机MySQL默认情况下，使用4G+4Core，关闭NUMA Balancing

基准数据

Innodb_flush_method = O_DIRECT

OLTP test statistics:
    queries performed:
        read:                            14000028
        write:                           5000010
        other:                           2000004
        total:                           21000042
    transactions:                        1000002 (1375.45 per sec.)
    deadlocks:                           0      (0.00 per sec.)
    read/write requests:                 19000038 (26133.48 per sec.)
    other operations:                    2000004 (2750.89 per sec.)

Test execution summary:
    total time:                          727.0382s
    total number of events:              1000002
    total time taken by event execution: 17443.5464
    per-request statistics:
         min:                                  1.78ms
         avg:                                 17.44ms
         max:                               1048.03ms
         approx.  95 percentile:              32.64ms

Threads fairness:
    events (avg/stddev):           41666.7500/646.28
    execution time (avg/stddev):   726.8144/0.00

关闭 Innodb_flush_method = O_DIRECT, 使用默认值

OLTP test statistics:
    queries performed:
        read:                            14000028
        write:                           5000010
        other:                           2000004
        total:                           21000042
    transactions:                        1000002 (1390.26 per sec.)
    deadlocks:                           0      (0.00 per sec.)
    read/write requests:                 19000038 (26414.92 per sec.)
    other operations:                    2000004 (2780.52 per sec.)

Test execution summary:
    total time:                          719.2920s
    total number of events:              1000002
    total time taken by event execution: 17257.6867
    per-request statistics:
         min:                                  1.78ms
         avg:                                 17.26ms
         max:                               1476.86ms
         approx.  95 percentile:              32.76ms

Threads fairness:
    events (avg/stddev):           41666.7500/709.66
    execution time (avg/stddev):   719.0703/0.00

基准数据分析

在物理机MySQL实例情况下，innodb_flush_method对MySQL性能有一定影响关系

测试结果

第一次压测，KVM环境下 (单一变量 innodb_flush_method)

单纯虚拟机(kvm)压测, Innodb_flush_method = O_DIRECT
打开 Numa balancing, kvm cache模式改为 writethrough

KVM 配置:
    CPU = 4 core
    Mem = 5 G
    MySQL = 4G
    Cache = writethrough
MySQL 配置:
    Mem = 4G
    Innodb_flush_method = O_DIRECT

Innodb_flush_method = O_DIRECT

sysbench --test=oltp --oltp-table-size=1000000  --mysql-db=test --max-requests=1000000 --num-threads=24 --mysql-host=192.168.100.244 --mysql-user=test run

OLTP test statistics:
    queries performed:
        read:                            14000042
        write:                           5000015
        other:                           2000006
        total:                           21000063
    transactions:                        1000003 (1041.22 per sec.)
    deadlocks:                           0      (0.00 per sec.)
    read/write requests:                 19000057 (19783.20 per sec.)
    other operations:                    2000006 (2082.44 per sec.)

Test execution summary:
    total time:                          960.4138s
    total number of events:              1000003
    total time taken by event execution: 23044.1587
    per-request statistics:
         min:                                  3.43ms
         avg:                                 23.04ms
         max:                                958.60ms
         approx.  95 percentile:              43.71ms

Threads fairness:
    events (avg/stddev):           41666.7917/865.32
    execution time (avg/stddev):   960.1733/0.01

Innodb_flush_method = DEFAULT(O_SYNC)

sysbench 0.4.12:  multi-threaded system evaluation benchmark

OLTP test statistics:
    queries performed:
        read:                            14000042
        write:                           5000015
        other:                           2000006
        total:                           21000063
    transactions:                        1000003 (1025.90 per sec.)
    deadlocks:                           0      (0.00 per sec.)
    read/write requests:                 19000057 (19492.01 per sec.)
    other operations:                    2000006 (2051.79 per sec.)

Test execution summary:
    total time:                          974.7614s
    total number of events:              1000003
    total time taken by event execution: 23388.1224
    per-request statistics:
         min:                                  3.75ms
         avg:                                 23.39ms
         max:                               1306.42ms
         approx.  95 percentile:              44.38ms

Threads fairness:
    events (avg/stddev):           41666.7917/863.10
    execution time (avg/stddev):   974.5051/0.01

第一次压测总结

从压测报告显示，在kvm打开writethrough前提下，O_DIRECT方式，MySQL的效率更高
使用kvm，MySQL性能约为物理机的75%
纵坐标为总执行时间

IO模式建议优化手段

在宿主机打开writethrough前提下，配置 Innodb_flush_method = O_DIRECT有效提高MySQL性能
约为物理机O_DIRECT模式下性能的97%

第二次压测, KVM环境下 (单一变量 numa balancing)

单纯虚拟机(kvm)压测, 打开 numa balancing
关闭宿主机 Numa balancing, kvm cache模式改为 writethrough
Innodb_flush_method = O_SYNC

OLTP test statistics:
    queries performed:
        read:                            14000014
        write:                           5000005
        other:                           2000002
        total:                           21000021
    transactions:                        1000001 (1068.76 per sec.)
    deadlocks:                           0      (0.00 per sec.)
    read/write requests:                 19000019 (20306.35 per sec.)
    other operations:                    2000002 (2137.51 per sec.)

Test execution summary:
    total time:                          935.6690s
    total number of events:              1000001
    total time taken by event execution: 22450.9403
    per-request statistics:
         min:                                  3.51ms
         avg:                                 22.45ms
         max:                               1170.10ms
         approx.  95 percentile:              41.65ms

Threads fairness:
    events (avg/stddev):           41666.7083/855.51
    execution time (avg/stddev):   935.4558/0.01

Innodb_flush_method = O_DIRECT

OLTP test statistics:
    queries performed:
        read:                            14000042
        write:                           5000015
        other:                           2000006
        total:                           21000063
    transactions:                        1000003 (1062.79 per sec.)
    deadlocks:                           0      (0.00 per sec.)
    read/write requests:                 19000057 (20193.07 per sec.)
    other operations:                    2000006 (2125.59 per sec.)

Test execution summary:
    total time:                          940.9197s
    total number of events:              1000003
    total time taken by event execution: 22577.0003
    per-request statistics:
         min:                                  3.36ms
         avg:                                 22.58ms
         max:                                756.58ms
         approx.  95 percentile:              41.50ms

Threads fairness:
    events (avg/stddev):           41666.7917/943.69
    execution time (avg/stddev):   940.7083/0.01

第二次压测总结

打开NUMA绑定后，性能下降约3%

CPU优化建议

关闭NUMA绑定

Q&A

为什么不采用多个实例做高负载压测？

在测试的过程中，利用cgroup可以将实例的CPU全部跑到对应的核，在对应CPU上，负载是满的

为什么NUMA对性能影响如此之大？

猜测vCPU的多个线程可能位于不同的CPU Nodes, 导致跨node的内存访问，不太清楚vCPU是否会产生这样的调度，但是关闭NUMA是不会导致的。

有没有一张图解释不同kvm cache？