Public bug reported:
Summary:
Ubuntu 10.04 hangs when the CPU scaling governor is set to "ondemand",
"conservative", or "userspace" at 1000 MHz and 900 MHz. Other freqs don't hang.
Motherboard: Jetway NF77-N1G6-LF
CPU: VIA Nano processor L2200@1600MHz
Ubuntu installer: Ubuntu 10.04.1 64-bit alternate
Test setup:
- Install Ubuntu 10.04.1 64-bit from an alternate CD or an alternate USB stick.
- As soon as you reach the login screen, quickly press CTRL+ALT+F6 to go to a
terminal, then quickly type "sudo chmod -x /etc/init.d/ondemand". The quickly
type "sudo reboot" to reboot the computer. This will disable the ondemand
script from changing the cpu governor on the next boot.
- On the next boot, log in normally, then update all packages from the Update
Manager, and reboot if necessary.
- Launch a Terminal window. All test cmds will be executed from this directory:
$ cd /sys/devices/system/cpu/cpu0/cpufreq
- Open a 2nd Terminal window and execute this so you can watch the CPU freq.
$ watch -n0 "cat /proc/cpuinfo"
Test:
- Check the available and current governor, the available freqs, and the
scaling driver.
$ cat scaling_available_governors
conservative ondemand userspace powersave performance
$ cat scaling_governor
performance
$ cat scaling_available_frequencies
1600000 1400000 1300000 1200000 1100000 1000000 900000 800000
$ cat scaling_driver
acpi-cpufreq
- Try powersave. The CPU drops to 800 MHz. No hang.
$ echo -n powersave | sudo tee scaling_governor
- Try ondemand. Ubuntu hangs after I press enter.
$ echo -n ondemand | sudo tee scaling_governor
- Reboot, then try conservative. Ubuntu hangs a moment after I press enter. I
observed the CPU freq dropping to 1400 MHz, then 1300 MHz, 1200 MHz, 1100 MHz,
then hang.
$ echo -n conservative | sudo tee scaling_governor
- Reboot, then try userspace. No hang at this point. CPU freq is 1600 MHz.
$ echo -n userspace | sudo tee scaling_governor
- Manually change the CPU freq. These changes don't hang. The CPU freq is
correctly changed to the specified freq.
$ echo -n 1400000 | sudo tee scaling_setspeed
$ echo -n 1300000 | sudo tee scaling_setspeed
$ echo -n 1200000 | sudo tee scaling_setspeed
$ echo -n 1100000 | sudo tee scaling_setspeed
- Now try 1000 MHz. This hangs instantly.
$ echo -n 1000000 | sudo tee scaling_setspeed
- Reboot, try 900 MHz. This hangs instantly.
$ echo -n 900000 | sudo tee scaling_setspeed
- Reboot, try 800 MHz. CPU freq changed to 800 Mhz. No hang.
$ echo -n 800000 | sudo tee scaling_setspeed
END OF TEST
Other notes:
- Some other info about my installation.
$ uname -srvmpio
Linux 2.6.32-32-generic #62-Ubuntu SMP Wed Apr 20 21:52:38 UTC 2011 x86_64
unknown unknown GNU/Linux
$ lsb_release -rd
Description: Ubuntu 10.04.2 LTS
Release: 10.04
$ apt-cache policy linux-image-generic
linux-image-generic:
Installed: 2.6.32.32.38
Candidate: 2.6.32.32.38
Version table:
*** 2.6.32.32.38 0
500 http://us.archive.ubuntu.com/ubuntu/ lucid-updates/main Packages
500 http://security.ubuntu.com/ubuntu/ lucid-security/main Packages
100 /var/lib/dpkg/status
2.6.32.21.22 0
500 http://us.archive.ubuntu.com/ubuntu/ lucid/main Packages
- If the CPU is already at 800 MHz, "ondemand" sometimes doesn't hang
instantly. My guess is that the hang occurs when a process in the
background pushes the CPU to 1600 MHz, then ondemand hangs when it tries
to quickly scale the CPU freq back down to 800 MHz.
- I have a different motherboard that also has a VIA Nano L2200 CPU. The
board is a VIA VB8001. There is no problem with ondemand on that board
because "/sys/devices/system/cpu/cpu0/cpufreq" doesn't even exist. I
have no idea why.
** Affects: linux-meta (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/805205
Title:
VIA Nano hangs on some CPU scaling governors
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