backporting timer fix to dapper

Andrew Straw strawman at
Wed Jul 19 04:45:22 UTC 2006

Hi Brian,

Speaking only as a Ubuntu kernel patching newbie, I suggest reading , especially as it appears you're
using git. It sounds straightforward to apply the patches you mention to
the Dapper tree. Then use git-format-patch to create an email to the
kernel-team mailing list. If accepted, your patch will then be applied.
This method creates the least work for the maintainers.


Brian Eaton wrote:
> Hi folks -
> Is there any chance that some fixes from the 2.6.16 kernel tree could
> be backported to Dapper?  There is a bug in the 2.6.15 kernel that
> causes timer interrupts to go missing on some laptops, leading to
> serious performance problems.  Symptoms include horrible bad graphics,
> audio and keyboard performance, and high power consumption.  The only
> consistent workaround seems to be to set max_cstate to either 1 or 2,
> though some people report that switching from the 686 to the 386
> kernel helps.
> An explanation of the problem may be found here:
> Venkatesh's initial series of three patches was later supplemented
> with a couple of others.  I've done a little bit of digging, and I
> think a total of six patches are actually needed.  These apply cleanly
> to the current dapper kernel, and together they fix the problem:
> 5a07a30c3cc4dc438494d6416ffa74008a2194b3
> 6eb0a0fd059598ee0d49c6283ce25cccd743e9fc
> d25bf7e5fe73b5b6d2246ab0be08ae35d718456b
> 76b461c21468f41837283b7888d55f1c0671f719
> bd6633476922b7b51227f7f704c2546e763ae5ed
> 0b5c59a1e41636afa77b90d34e8c394d8d929733
> There are several open dapper bugs that I think all have the same root
> cause, the missing timer interrupts.  I didn't do anything like an
> exhaustive search through the bug database, but I suspect all of these
> are related:
> 30557 - definitely this problem
> 34641 - maybe
> 44391 - maybe
> 44912 - probably
> 50153 - probably
> 50341 - definitely
> 53404 - definitely
> This seems like a fairly large change to make to the dapper kernel,
> but the main fix has been in the trees for about six
> months, with the last tweak (making the fix apply to AMD CPUs as well
> as Intel) in March.  The fix ought to be solid at this point.
> Thanks for the work you've put in to Ubuntu.  It's a pleasure to use.
> Regards,
> Brian

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