Ubuntu 18.04 启动太慢不能忍

$ systemd-analyze blame 

$ systemd-analyze blame 
         35.576s plymouth-quit-wait.service
         22.644s dev-sda2.device
         17.528s systemd-journal-flush.service
         10.712s NetworkManager-wait-online.service
          9.930s snapd.service
          9.329s keyboard-setup.service
          9.289s systemd-tmpfiles-setup-dev.service
          8.665s mysql.service
          8.510s systemd-sysctl.service
          7.092s plymouth-start.service
          6.583s vmware-workstation-server.service
          6.115s NetworkManager.service
          5.682s udisks2.service
          5.627s networking.service
          5.397s networkd-dispatcher.service
          5.326s vmware-USBArbitrator.service
          5.305s vboxdrv.service
          5.292s bolt.service
          ......

$ sudo systemctl mask plymouth-quit-wait.service