From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752199Ab3GIB0P (ORCPT ); Mon, 8 Jul 2013 21:26:15 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:50534 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751672Ab3GIB0N (ORCPT ); Mon, 8 Jul 2013 21:26:13 -0400 Date: Tue, 9 Jul 2013 03:26:11 +0200 From: Pavel Machek To: kernel list , Greg KH Cc: joe.lawrence@stratus.com, myron.stowe@redhat.com, bhelgaas@google.com Subject: /sys/module/pcie_aspm/parameters/policy not writable? Message-ID: <20130709012611.GA22371@amd.pavel.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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