Latest working kernel version: 2.6.27.10 Earliest failing kernel version: 2.6.28 Distribution: Arch Linux Hardware Environment: x86 Software Environment: x86 Problem Description: With 2.6.27.10 I get about 10 wakeups per second as reported by powertop (on an idle system), but after upgrading to 2.6.28 I get about 100 extra wakeups due to: <interrupt> : uhci_hcd:usb1, i915@pci:0000:00:02.0 The interesting thing is that if I suspend (to disk or to RAM) the system and then resume it, those extra wakeups go away. This is an old Pentium 4 desktop with i845GL chipset. The kernels used are the stock ones from Arch Linux (pretty vanilla kernels, and I don't even know how to compile my own anyway). I'll attach dmesg from 2.6.27.10, 2.6.28 and 2.6.28 after resume from hibernation. Thanks.
Created attachment 19575 [details] dmesg log from 2.6.27.10
Created attachment 19576 [details] dmesg log from 2.6.28
Created attachment 19577 [details] dmesg log from 2.6.28 after resume from hibernation
I've found that switching to console and back to X fixes the problem too. Same if I start the system in runlevel 2 and then start X manually. So it looks like a simple timing problem, as if X starts before it should (?).
this is probably an issue with getting vblank interrupts turned off because we lose track of the state during X startup. jbarnes had been looking into an issue like this before.
On Wednesday 04 February 2009, Alberto Gonzalez wrote: > --- On Wed, 2/4/09, Rafael J. Wysocki <rjw@sisk.pl> wrote: > > > The following bug entry is on the current list of known > > regressions > > introduced between 2.6.27 and 2.6.28. Please verify if it > > still should > > be listed and let me know (either way). > > > > > > Bug-Entry : > > http://bugzilla.kernel.org/show_bug.cgi?id=12337 > > Subject : ~100 extra wakeups reported by powertop > > Submitter : Alberto Gonzalez <luis6674@yahoo.com> > > Date : 2008-12-31 12:25 (36 days old) > > Yes, still present in latest stable 2.6.28.3
I got a new computer, a Dell Studio desktop based on an Intel G45 chipset (using the integrated graphics), and I have the exact same problem. After booting I have around 75 wakeups per second from the same source, and switching to console and back to X also fixes the problem. If it happened on my 5+ year old Pentium 4 (on a 32 bit kernel) and it happens on a new Core 2 duo (on a 64 bit kernel), it's unlikely I'm the only one seeing this, so hopefully someone with better knowledge can reproduce the problem and help better to fix it.
HOW TO REPRODUCE: (taken from a post by Alberto Gonzalez to LKML): ---8<--- Since Arch Linux is not popular among kernel developers I just tested Fedora 10 Live-CD (KDE) and I can reproduce the exact same problem, even if Fedora 10 has kernel 2.6.27 and for me the problem appeared in .28 (but I guess Fedora adds many patches, so probably the "guilty" commit was backported to 2.6.27.5-117-FC10-i686). Steps: - Boot into Fedora 10 Live CD (obviously, into the default graphical mode) - Install Powertop (yum install powertop) and run - I get about 60 wakeups per second from i915@pci.... leaving the system idle - Switch to console and back to X. The wakeups are gone.
Also tracked at: http://bugs.freedesktop.org/show_bug.cgi?id=20296
On Tuesday 24 February 2009, Alberto Gonzalez wrote: > --- On Mon, 2/23/09, Rafael J. Wysocki <rjw@sisk.pl> wrote: > > > The following bug entry is on the current list of known > > regressions > > introduced between 2.6.27 and 2.6.28. Please verify if it > > still should > > be listed and let me know (either way). > > > > > > Bug-Entry : > > http://bugzilla.kernel.org/show_bug.cgi?id=12337 > > Subject : ~100 extra wakeups reported by powertop > > Submitter : Alberto Gonzalez <luis6674@yahoo.com> > > Date : 2008-12-31 12:25 (55 days old) > > Still present, yes.
On Tuesday 03 March 2009, Alberto Gonzalez wrote: > --- On Tue, 3/3/09, Rafael J. Wysocki wrote: > > > The following bug entry is on the current list of known > > regressions > > introduced between 2.6.27 and 2.6.28. Please verify if it > > still should > > be listed and let me know (either way). > > > > > > Bug-Entry : > > http://bugzilla.kernel.org/show_bug.cgi?id=12337 > > Subject : ~100 extra wakeups reported by powertop > > Submitter : Alberto Gonzalez <luis6674@yahoo.com> > > Date : 2008-12-31 12:25 (63 days old) > > J. Barnes said this is a bug in the intel driver, even if it appeared after a > kernel upgrade. > > If you prefer to close it for now, fine with me. If you prefer to wait until > it's confirmed, fine too. Whatever is ore convenient for your tracking. > > I'll update the report in any case when I know more.