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连接交流适配器时无法写入 /sys/devices/system/cpu/cpufreq/*/energy_performance_preference

tag-icon • tag-icon gentoo cpu-frequency sysfs
连接交流适配器时无法写入 /sys/devices/system/cpu/cpufreq/*/energy_performance_preference

交流适配器已拔出：

$ echo power | sudo tee energy_performance_preference
power
$ echo $?
0

交流适配器已插入：

$ echo power | sudo tee energy_performance_preference
power
tee: energy_performance_preference: Device or resource busy

是的，我有英特尔 p 状态 HWP- 有能力的CPU，否则我不会有上面那个设置。

我的笔记本电脑运行的是经过内核强化的 Gentoo Linux 5.17.4-gentoo-x86_64。

也许有某种关联，但是/var/log/系统日志显示拔掉适配器后：

May 27 17:19:27 mathroom laptop-mode: enabled, active
May 27 17:19:27 mathroom rfkill: block set for type bluetooth
May 27 17:19:27 mathroom laptop-mode: LCD Brightness Command succeeded.
May 27 17:19:27 mathroom kernel: EXT4-fs (sda3): re-mounted. Quota mode: disabled.
May 27 17:19:27 mathroom kernel: EXT4-fs (sda4): re-mounted. Quota mode: disabled.
May 27 17:19:27 mathroom kernel: r8169 0000:02:00.0 enp2s0: Link is Down
May 27 17:19:28 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000080 00000001
May 27 17:19:28 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000081 00000001
May 27 17:19:28 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000080 00000001
May 27 17:19:28 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000001 00000001

，插回去之后是这样的：

May 27 17:20:36 mathroom laptop-mode: enabled, active
May 27 17:20:36 mathroom rfkill: unblock set for type bluetooth
May 27 17:20:36 mathroom laptop-mode: LCD Brightness Command succeeded.
May 27 17:20:36 mathroom kernel: NMI watchdog: Enabled. Permanently consumes one hw-PMU counter.
May 27 17:20:36 mathroom kernel: EXT4-fs (sda3): re-mounted. Quota mode: disabled.
May 27 17:20:36 mathroom kernel: EXT4-fs (sda4): re-mounted. Quota mode: disabled.
May 27 17:20:36 mathroom kernel: r8169 0000:02:00.0 enp2s0: Link is Down
May 27 17:20:36 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000080 00000001
May 27 17:20:36 mathroom root: ACPI event unhandled: ac_adapter ACPI0003:00 00000080 00000001
May 27 17:20:37 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000081 00000001
May 27 17:20:37 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000080 00000001
May 27 17:20:37 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000001 00000001

还有，没有diff-erence/etc/mtab更改适配器状态之前和之后。

值得注意的是，例如，在连接交流适配器时，我可以写入scaling_governor，但不能写入energy_performance_preference。

这帖子对我没有帮助（lsof +D /sys输出不相关）。

任何帮助将不胜感激。

答案1

以下命令的输出是什么（我知道这个问题更适合评论，但我还没有足够的声誉）：

$ cat /sys/devices/system/cpu/cpufreq/*/energy_performance_available_preferences  
$ cat /sys/devices/system/cpu/cpufreq/*/scaling_governor

在我的 Arch Linux 上，amd_pstate_epp当 myscaling_governor设置为时，performance我只能选择performance作为 EPP 首选项（energy_performance_available_preferences也仅包含performance）。当我尝试选择不可用的 EPP 首选项时，出现错误Device or resource busy。也许插入交流适配器会改变您的调速器设置？

$ uname -a
Linux some-hostname 6.7.4-arch1-1 #1 SMP PREEMPT_DYNAMIC Mon, 05 Feb 2024 22:07:49 +0000 x86_64 GNU/Linux
$ cd /sys/devices/system/cpu/cpufreq/policy0/
$ echo powersave | sudo tee scaling_governor
powersave
$ cat energy_performance_available_preferences
default performance balance_performance balance_power power
$ echo power | sudo tee energy_performance_preference 
power
$ echo performance | sudo tee scaling_governor
performance
$ cat energy_performance_available_preferences       
performance
$ echo power | sudo tee energy_performance_preference
power
tee: energy_performance_preference: Device or resource busy

然而，其确切原因超出了我的了解。

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