我刚刚在 Athlon X4 740 系统上安装了 Ubuntu Studio（具有低延迟内核），该系统之前运行 Ubuntu 14.04 已有数年，然后运行 18.04 一段时间，现在运行这个，因为我要将此机箱专用于音频内容，并希望为此目的对其进行优化。因此，我在其他 Ubuntu 版本上使用完全相同的硬件时没有出现此问题。
我已将此设备连接到 USB/VGA 类型的 IoGear KVM 切换器以及 Windows 10 计算机和运行 Ubuntu 16.04 的 Gigabyte “Brix” 系统。只有最近在我的 mini-ITX 机箱上安装的 Ubuntu Studio 才出现问题。
实际上，我现在最怀疑的是 KVM，尽管为什么“它以前能用”这一点令人费解。也许是因为盒子本身的 USB 端口出了问题。有时键盘也没有反应，但将 KVM 切换到与之连接的另外 2 台 PC 中的任意一台，一切就都正常了。
a) 如果我输入得太快，USB 键盘输入（也在 KVM 上）就会丢失字符，例如双字母。
b) Logitech 325 鼠标（在 Unifying 接收器上）没有完全冻结，但几乎不动。通过其他 USB 端口连接的有线 USB 鼠标不顺畅，但可以使用。
但有时，当我启动时，这种情况不会发生，无线鼠标和 USB 键盘可以快速流畅地工作。目前，大约每 5 次启动中就有 1 次可以正常启动。
larry@ub-studio:~$ xinput
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ PixArt Microsoft USB Optical Mouse id=13 [slave pointer (2)]
⎜ ↳ Logitech M325 id=14 [slave pointer (2)]
⎜ ↳ Microsoft Wired Keyboard 600 Consumer Control id=11 [slave pointer (2)]
⎣ Virtual core keyboard id=3 [master keyboard (2)]
↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]
↳ Power Button id=6 [slave keyboard (3)]
↳ Video Bus id=7 [slave keyboard (3)]
↳ Power Button id=8 [slave keyboard (3)]
↳ Microsoft Wired Keyboard 600 id=9 [slave keyboard (3)]
↳ Microsoft Wired Keyboard 600 System Control id=10 [slave keyboard (3)]
↳ Microsoft Wired Keyboard 600 Consumer Control id=12 [slave keyboard (3)]
larry@ub-studio:~$
上面的结果是鼠标出现故障时的结果。我最近没有看到它出现故障，因此无法进行比较。当我使用 KVM 切换到 Windows 或其他 Ubuntu 系统时，它运行正常。我还没有尝试过背面的不同 USB 端口，但那是下一步。
larry@ub-studio:~$ dmesg | grep -i mouse
[ 1.113250] mousedev: PS/2 mouse device common for all mice
[ 2.481843] input: Logitech Unifying Device. Wireless PID:400a Mouse as /devices/pci0000:00/0000:00:12.0/usb3/3-2/3-2:1.2/0003:046D:C52B.0005/0003:046D:400A.0006/input/input6
[ 2.481986] hid-generic 0003:046D:400A.0006: input,hidraw3: USB HID v1.11 Mouse [Logitech Unifying Device. Wireless PID:400a] on usb-0000:00:12.0-2:1
[ 2.507654] logitech-hidpp-device 0003:046D:400A.0006: input,hidraw3: USB HID v1.11 Mouse [Logitech M325] on usb-0000:00:12.0-2:1
[ 3.174538] usb 3-3: Product: Microsoft USB Optical Mouse
[ 3.181895] input: PixArt Microsoft USB Optical Mouse as /devices/pci0000:00/0000:00:12.0/usb3/3-3/3-3:1.0/0003:045E:00CB.0007/input/input11
[ 3.182216] hid-generic 0003:045E:00CB.0007: input,hidraw4: USB HID v1.11 Mouse [PixArt Microsoft USB Optical Mouse] on usb-0000:00:12.0-3/input0
[ 3439.831928] logitech-hidpp-device 0003:046D:400A.000D: input,hidraw3: USB HID v1.11 Mouse [Logitech M325] on usb-0000:00:12.0-2:1
larry@ub-studio:~$
larry@ub-studio:~$ dmesg | grep -i logitech
[ 2.353461] usb 3-2: Manufacturer: Logitech
[ 2.374388] logitech-djreceiver 0003:046D:C52B.0005: hiddev0,hidraw2: USB HID v1.11 Device [Logitech USB Receiver] on usb-0000:00:12.0-2/input2
[ 2.481843] input: Logitech Unifying Device. Wireless PID:400a Mouse as /devices/pci0000:00/0000:00:12.0/usb3/3-2/3-2:1.2/0003:046D:C52B.0005/0003:046D:400A.0006/input/input6
[ 2.481986] hid-generic 0003:046D:400A.0006: input,hidraw3: USB HID v1.11 Mouse [Logitech Unifying Device. Wireless PID:400a] on usb-0000:00:12.0-2:1
[ 2.507522] input: Logitech M325 as /devices/pci0000:00/0000:00:12.0/usb3/3-2/3-2:1.2/0003:046D:C52B.0005/0003:046D:400A.0006/input/input10
[ 2.507654] logitech-hidpp-device 0003:046D:400A.0006: input,hidraw3: USB HID v1.11 Mouse [Logitech M325] on usb-0000:00:12.0-2:1
[ 48.470347] logitech-hidpp-device 0003:046D:400A.0006: Can not get the protocol version.
[ 50.731246] Modules linked in: cmac bnep nls_iso8859_1 nvidia_uvm(POE) snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm nvidia(POE) snd_seq_midi btusb joydev snd_seq_midi_event arc4 snd_rawmidi btrtl input_leds iwlmvm snd_seq edac_mce_amd btbcm btintel snd_seq_device mac80211 bluetooth kvm_amd snd_timer ecdh_generic ccp snd iwlwifi kvm irqbypass soundcore k10temp cfg80211 drm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 crypto_simd cryptd mac_hid glue_helper sch_fq_codel cuse parport_pc ppdev lp parport ip_tables x_tables autofs4 hid_logitech_hidpp hid_logitech_dj pata_acpi hid_generic usbhid hid i2c_piix4 pata_atiixp r8169 ahci realtek libahci video
[ 52.006389] logitech-hidpp-device 0003:046D:400A.0006: HID++ 2.0 device connected.
[ 281.963682] logitech-hidpp-device 0003:046D:400A.0006: hidpp20_batterylevel_get_battery_capacity: received protocol error 0x09
[ 2105.769626] logitech-hidpp-device 0003:046D:400A.0006: hidpp20_batterylevel_get_battery_capacity: received protocol error 0x09
[ 2497.141240] logitech-hidpp-device 0003:046D:400A.0006: hidpp20_batterylevel_get_battery_capacity: received protocol error 0x09
[ 3118.252873] logitech-hidpp-device 0003:046D:400A.0006: hidpp20_batterylevel_get_battery_capacity: received protocol error 0x09
[ 3436.919596] usb 3-2: Manufacturer: Logitech
[ 3438.584052] logitech-djreceiver 0003:046D:C52B.000C: hiddev0,hidraw2: USB HID v1.11 Device [Logitech USB Receiver] on usb-0000:00:12.0-2/input2
[ 3439.831760] input: Logitech M325 as /devices/pci0000:00/0000:00:12.0/usb3/3-2/3-2:1.2/0003:046D:C52B.000C/0003:046D:400A.000D/input/input19
[ 3439.831928] logitech-hidpp-device 0003:046D:400A.000D: input,hidraw3: USB HID v1.11 Mouse [Logitech M325] on usb-0000:00:12.0-2:1
larry@ub-studio:~$
[更新 #1] 我更换了 KVM 连接处的后部 USB 电缆。看起来此系统上有 USB 1.1、2.0 和 3.0 端口（在 lsusb 上）。以前键盘和 Logitech 接收器在 1.1 总线上。现在它们在 2.0 总线上，我重新启动了。
有线鼠标（其 USB 连接没有改变）和无线鼠标在启动后都可以正常工作。登录几秒钟后，无线鼠标完全锁定，而有线鼠标继续正常工作。
我认为键盘运行更顺畅，不会丢失字符。tttttttttt 应该是十个 t。是的。
[更新 #2] 再次重启。进入 BIOS 并关闭旧版 USB 支持。回到登录提示，无线鼠标运行顺畅，有线鼠标运行不稳定！登录后，无线鼠标锁定，有线鼠标继续运行，尽管运行不稳定。
键盘响应。tttttttttt ten t 看起来仍然正常。
我可以换成有线鼠标，至少它能用。那么问题来了，为什么有时很顺畅，而大多数时候却很卡顿？