Hi!
My thinkpad has rather high ping latencies... and perhaps it is due to
PCIE ASPM.
Its help text says:
CONFIG_PCIEASPM:
This enables OS control over PCI Express ASPM (Active State
Power Management) and Clock Power Management. ASPM supports
state L0/L0s/L1.
...
ASPM can be disabled or enabled at runtime via
/sys/module/pcie_aspm/parameters/policy
So I tried setting the parameter, but it seems to be broken :-(
root@amd:/data/pavel# cat /sys/module/pcie_aspm/parameters/policy
[default] performance powersave
root@amd:/data/pavel# echo performance > /sys/module/pcie_aspm/parameters/policy
bash: echo: write error: Operation not permitted
root@amd:/data/pavel# echo -n performance >
/sys/module/pcie_aspm/parameters/policy
bash: echo: write error: Operation not permitted
root@amd:/data/pavel# ls -al /sys/module/pcie_aspm/parameters/policy
-rw-r--r-- 1 root root 4096 Jul 9 03:16 /sys/module/pcie_aspm/parameters/policy
root@amd:/data/pavel# cat /sys/module/pcie_aspm/parameters/policy
[default] performance powersave
root@amd:/data/pavel# echo powersave > /sys/module/pcie_aspm/parameters/policy
bash: echo: write error: Operation not permitted
root@amd:/data/pavel# echo -n powersave >
/sys/module/pcie_aspm/parameters/policy
bash: echo: write error: Operation not permitted
root@amd:/data/pavel# echo -n default > /sys/module/pcie_aspm/parameters/policy
bash: echo: write error: Operation not permitted
Hmm:
CONFIG_PCIEASPM_DEFAULT=y
# CONFIG_PCIEASPM_POWERSAVE is not set
# CONFIG_PCIEASPM_PERFORMANCE is not set
Should we avoid displaying options that can't be selected?
Thanks,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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