Re: [Bug 189291] Low performance and lowest processor frequency for hp compaq 6715b - AMD Turion(tm) 64 X2

[Thomas Gleixner]

On Mon, 16 Jan 2017, bugzilla-daemon@xxxxxxxxxxxxxxxxxxx wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=189291
> 
> Zhang Rui <rui.zhang@xxxxxxxxx> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>            Assignee|rui.zhang@xxxxxxxxx         |tglx@xxxxxxxxxxxxx
> 
> --- Comment #13 from Zhang Rui <rui.zhang@xxxxxxxxx> ---
> (In reply to Vladimir Marko from comment #12)
> > If you followed the link in comment #9 (posted 2016-12-09), you would have
> > found the results of the bisect for Ubuntu (posted 2016-11-30) and two
> > possible patches (posted 2016-12-08).
> > 
> > The bisect for Ubuntu yields
> > 
> > 3b806e2b94cad37a8809df7c86f7cfdcd3baa719 is the first bad commit
> > commit 3b806e2b94cad37a8809df7c86f7cfdcd3baa719
> > Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Date: Mon Sep 14 12:00:55 2015 +0200
> > 
> >     x86/ioapic: Force affinity setting in setup_ioapic_dest()
> > 
> >     BugLink: http://bugs.launchpad.net/bugs/1509886
> > 
> >     commit 4857c91f0d195f05908fff296ba1ec5fca87066c upstream.
> > 
> >     ...
> > 
> > The commit 4857c91f0d195f05908fff296ba1ec5fca87066c does not revert cleanly
> > in the current kernel tree but it's rather trivial to do it manually. The
> > two possible patches I posted on the Ubuntu bug were successfully tested to
> > fix the issue.
> 
> Cool. Thanks for your effort.
> And we have two fixes that have been verified to fix the problem
> https://launchpadlibrarian.net/297109286/revert.patch
> and
> https://launchpadlibrarian.net/297109378/alternative.patch

Neither of those two are fixes. They paper over the problem.

What's worse they reintroduce the regression which was fixed with this
commit.

The old code, i.e. before the conversion to the hierarchical irq domain
wrote directly to the io apic to set the destination and that got dropped
during the conversion. The bisected commit restored the original behaviour.

So now the question is why the revert or the other patch 'fixes' the problem.

Can I please get for both the unmodified kernel and the patched kernel the
following information:

  Boot with apic=verbose on the kernel command line

  Gather dmesg output (full boot log)

  Output from 'cat /proc/interrupts'

Thanks,

	tglx