ubuntu 20安装gcc7

安装gcc7和g++7

sudo apt install gcc-7 g++-7

添加配置

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 90 --slave /usr/bin/g++ g++ /usr/bin/g++-9 --slave /usr/bin/gcov gcov /usr/bin/gcov-9
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-7 70 --slave /usr/bin/g++ g++ /usr/bin/g++-7 --slave /usr/bin/gcov gcov /usr/bin/gcov-7

切换gcc版本

sudo update-alternatives --config gcc

mysql 8.0.22有性能回退

测试命令

sysbench --test=oltp_read_write --tables=10 --table-size=1000000 --report-interval=10 --time=3600 --threads=50 --db-driver=mysql --mysql-socket=/tmp/mysql.sock --mysql-user=root --mysql-password='xxxx' --mysql-db=sbtest run

8.0.21 测试结果

SQL statistics:
    queries performed:
        read:                            15339058
        write:                           4382588
        other:                           2191294
        total:                           21912940
    transactions:                        1095647 (304.28 per sec.)
    queries:                             21912940 (6085.57 per sec.)
    ignored errors:                      0      (0.00 per sec.)
    reconnects:                          0      (0.00 per sec.)

General statistics:
    total time:                          3600.8045s
    total number of events:              1095647

Latency (ms):
         min:                                    2.74
         avg:                                  164.30
         max:                                 5033.06
         95th percentile:                      707.07
         sum:                            180014353.79

Threads fairness:
    events (avg/stddev):           21912.9400/80.08
    execution time (avg/stddev):   3600.2871/0.22

8.0.23 测试结果

SQL statistics:
    queries performed:
        read:                            2969064
        write:                           848304
        other:                           424152
        total:                           4241520
    transactions:                        212076 (58.89 per sec.)
    queries:                             4241520 (1177.79 per sec.)
    ignored errors:                      0      (0.00 per sec.)
    reconnects:                          0      (0.00 per sec.)

General statistics:
    total time:                          3601.2587s
    total number of events:              212076

Latency (ms):
         min:                                    3.57
         avg:                                  848.89
         max:                                 6098.82
         95th percentile:                     1973.38
         sum:                            180029441.14

Threads fairness:
    events (avg/stddev):           4241.5200/32.35
    execution time (avg/stddev):   3600.5888/0.34

mysql 8.0 关闭binlog

清空日志

mysql> reset master;

查询是否开启了binlog

$mysql -uroot -p
mysql>use mysql;
mysql>
mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin       | ON    |
+---------------+-------+
1 row in set (0.01 sec)

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MBP ubuntu从18升级到20启动错误修正

错误信息:

Failed to Set MokListRT: Invalid Parameter
Could not create mokListRT: Invalid Parameter
Importing MOK states has failed: import_mok_state() failed: Invalid Parameter
Continuing boot since secure mode is disabled.

修正:

sudo su -
cd /boot/efi/EFI/ubuntu
cp grubx64.efi shimx64.efi
reboot

参考:(Ubuntu 20.04 Failed to Set MokListRT: Invalid Parameter)[https://askubuntu.com/questions/1279602/ubuntu-20-04-failed-to-set-moklistrt-invalid-parameter]

cocos2d-x 4.0 captureNode用法备份

-- 截取场景
cc.utils:captureNode(scene, function(image)
    -- 图片转纹理
    local texture = cc.Texture2D:new()
    texture:initWithImage(image)
    image:release()
    -- 纹理创建精灵
    local sp = cc.Sprite:createWithTexture(texture)
    sp:addTo(scene):center()
end)