Kernel Bug Tracker – Bug 18272
2.6.35.*: horrible (exponential? >linear) slowdown to unusability (ACPI idle?)
Last modified: 2010-09-20 20:43:06 UTC
Subject : 2.6.35.*: horrible (exponential? >linear) slowdown to unusability (ACPI idle?)
Submitter : Nix <firstname.lastname@example.org>
Date : 2010-09-05 0:51
Message-ID : email@example.com
References : http://marc.info/?l=linux-kernel&m=128364994602942&w=2
This entry is being used for tracking a regression from 2.6.34. Please don't
close it until the problem is fixed in the mainline.
Author: Thomas Gleixner <firstname.lastname@example.org>
Date: Tue Apr 13 15:31:36 2010 +0200
x86, hpet: Restrict read back to affected ATI chipsets
After programming the HPET, we do a readback as a workaround for
ATI/SBx00 chipsets as a synchronization. Unfortunately this triggers
an erratum in newer ICH chipsets (ICH9+) where reading the comparator
immediately after the write returns the old value. Furthermore, as
always, I/O reads are bad for performance.
Therefore, restrict the readback to the chipsets that need it, or, for
debugging purposes, when we are running with hpet=verbose.
Signed-off-by: Thomas Gleixner <email@example.com>
Acked-by: Venkatesh Pallipadi <firstname.lastname@example.org>
Signed-off-by: H. Peter Anvin <email@example.com>
First-Bad-Commit : 30a564be9d9554c168a654eddc2165869cc0d7bf
On Monday, September 20, 2010, Nix wrote:
> On 20 Sep 2010, Rafael J. Wysocki said:
> > This message has been generated automatically as a part of a report
> > of regressions introduced between 2.6.34 and 2.6.35.
> > The following bug entry is on the current list of known regressions
> > introduced between 2.6.34 and 2.6.35. Please verify if it still should
> > be listed and let the tracking team know (either way).
> Resolved by 54ff7e595d763d894104d421b103a89f7becf47c in master,
> which is landing in 126.96.36.199 imminently.