backporting timer fix to dapper

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:

http://lkml.org/lk
ml/2005/12/8/304

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 kernel.org 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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Hi Brian,

Speaking only as a Ubuntu kernel patching newbie, I suggest
reading
https://wiki.u
buntu.com/KernelGitGuide , 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.

Cheers!
Andrew

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:
>
> http://lkml.org/lk
ml/2005/12/8/304
>
> 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 kernel.org 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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On Tue, 2006-07-18 at 21:45 -0700, Andrew Straw wrote:
> Hi Brian,
> 
> Speaking only as a Ubuntu kernel patching newbie, I
suggest reading
> https://wiki.u
buntu.com/KernelGitGuide , 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.

Technically, that's the correct way. However, it is the
least amount of
work to just do:

git-cherry-pick <git-sha>
(repeat as needed)

Plus, it keeps the repo consistent for when we sync to
upstream (where
the patches come from).

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SwissDisk  - http://www.swissdisk.com/


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