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SubjectRe: /sys/module/pcie_aspm/parameters/policy not writable?
On Mon 2013-07-08 21:13:21, Greg KH wrote:
> On Tue, Jul 09, 2013 at 03:26:11AM +0200, Pavel Machek wrote:
> > Hi!
> >
> > My thinkpad has rather high ping latencies... and perhaps it is due to
> > PCIE ASPM.
>
> Why would that be the problem? The odds that the PCIE bus is the issue
> seems strange to me.

Aha: I guess that's why the file is not writable:

pavel@amd:~$ dmesg | grep -i aspm
ACPI FADT declares the system doesn't support PCIe ASPM, so disable it
e1000e 0000:02:00.0: Disabling ASPM L0s L1
pavel@amd:~$ cat /sys/module/pcie_aspm/parameters/policy
[default] performance powersave
pavel@amd:~$
root@amd:~# echo -n performance >
/sys/module/pcie_aspm/parameters/policy
-su: echo: write error: Operation not permitted
root@amd:~#

But:
1) it should not list unavailable options

2) operation not permitted seems like wrong error code for
operation not supported.

Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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