On Thu, 2008-01-03 at 11:33 -0800, Kok, Auke wrote: > Shaohua Li wrote: > > PCI Express ASPM defines a protocol for PCI Express components in the D0 > > state to reduce Link power by placing their Links into a low power state > > and instructing the other end of the Link to do likewise. This > > capability allows hardware-autonomous, dynamic Link power reduction > > beyond what is achievable by software-only controlled power management. > > However, The device should be configured by software appropriately. > > Enabling ASPM will save power, but will introduce device latency. > > > > This patch adds ASPM support in Linux. It introduces a global policy for > > ASPM, a sysfs file /sys/module/pcie_aspm/parameters/policy can control > > it. The interface can be used as a boot option too. Currently we have > > below setting: > > -default, BIOS default setting > > -powersave, highest power saving mode, enable all available ASPM state > > and clock power management > > -performance, highest performance, disable ASPM and clock power > > management > > By default, the 'default' policy is used currently. > > > > In my test, power difference between powersave mode and performance mode > > is about 1.3w in a system with 3 PCIE links. > > > > please review, any comments will be appreciated. > > > quickly glanced this over since I recently disabled l1 ASPM for the > e1000/e1000e > driven 82573 device which has issues with l1 ASPM. that immediately gives me > the > question: how can I continue to disable 1l aspm by default for this device > using > this infrastructure? I used to have a per-device interface, but thought the interface might be hard to use for users. If we really need the per-device interface, I can re-add it.
> I do like the fact that there is a generic way to re-enable it for the users > who > want to use it. Can this change be done when the device is already active? Yes, at least in my test. > Can you > change this parameter per device/module? Another way is to provide a helper for driver, and driver disables specific ASPM states. It sounds better to let driver do the disabling, as users haven't the knowledge? Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
