Shaohua Li wrote: > 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?
agreed, however this could still be usefull in debugging equipment for the experienced user. In any case an easy handle for the driver to dis/enable ASPM would certainly help our case, and possibly others. Auke -- 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/
