Suspend and Resume with ACPI

Jeremy — Mon, 24 Sep 2007 01:35:12 +0000

"It took me quite a while to realize the real root cause of the VAIO - and probably many other machines - suspend/resume regressions, which were unearthed by the dyntick / clockevents patches," Thomas Gleixner explained regarding two patches for fixing suspend issues that Andrew Morton experienced with his VAIO laptop. He continued, "we disable a lot of ACPI/BIOS functionality during suspend, but we keep the lower idle C-states functionality active across suspend/resume. It seems that this causes trouble with certain BIOSes, but I assume that the problem is more wide spread and just not surfacing due to the various scenarios in which a machine goes into suspend/resume." Thomas concluded, "I really hope that this two patches finally set an end to the 'jinxed VAIO heisenbug series', which started when we removed the periodic tick with the clockevents/dyntick patches."

Linus Torvalds expressed some concerns, "the patches look fine, but I somehow have this slight feeling that you gave up a bit too soon on the '*why* does this happen?' question." He agreed that at that point there was a problem with ACPI, but cautioned that this could be triggered by another bug, "in particular, I also suspect that this may not really fix the problem - maybe it just makes the window sufficiently small that it no longer triggers. Because we don't necessarily understand what the real background for the problem is, I'm not sure we can say that it is solved." Linus concluded, "but hey, I think I'll apply the patches as-is. I'd just feel even better if we actually understood *why* doing the CPU Cx states is not something we can do around the suspend code!"

Power Saving Projects

Jeremy — Fri, 21 Sep 2007 08:53:55 +0000

"Intel's Open Source Technology Center is pleased to announce the LessWatts.org project, an open source project for saving power on Linux," began an email posted to the lkml by Arjan van de Ven. The announcement continued:

"LessWatts.org is a place to bring users, developers and distribution makers together around power reduction for linux machines, from mobile to desktop to server to datacenter. LessWatts.org is about a system-level approach to power savings, from the lowest level device drivers in the kernel to the most advanced desktop applications. LessWatts.org is about things you can do to reduce power usage. LessWatts.org is about longer battery life, a lower airconditioning bill, about reducing the impact of computers on the environment."

The announcement went on to note, "at this time of launching the LessWatts.org project, the technology development projects are those that Intel has started, is involved in or has just started working on, such as PowerTOP, Tickless Idle, Graphics and various link power management techniques. We'd like to invite all developers and projects that focus on power saving to join the LessWatts.org effort and community."

KernelTrap - laptop

Suspend and Resume with ACPI

Power Saving Projects