From: Rob Prowel <rprowel@comcast.net>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: AMD Athlon bogus performance value causing RCU stalls?
Date: Wed, 26 Sep 2018 19:38:09 -0400 [thread overview]
Message-ID: <38932eb1-921f-55f7-10c8-358f9aae32b2@comcast.net> (raw)
In-Reply-To: <alpine.DEB.2.21.1809232314460.1398@nanos.tec.linutronix.de>
On 09/23/18 17:19, Thomas Gleixner wrote:
>>
>> Other than RTFM, or please build a bunch of kernels from source on your slow
>> machine, using differing config options to help track down the cause of
>> this...any thoughts about a solution?
>
> Yes. This was decoded recently as an issue on 32bit due to a calculation
> which is based on 'unsigned long' but requires to be 64bit wide.
>
> It's in the 4.18.8 stable kernel, which should be available from your
> fedora repo anytime soon.
OK. Followup on AMD performance counter problem in 4.18.7
The Dell machine I was experiencing the problem on had a lot of ACPI
issues. One of the invalid ACPI entries was for a system timer.
dmesg suggests that the broken timer was used in calculating the
Athlon performance value. So no, 32/64 bit math was not the issue.
ACPI=off in the kernel boot line fixed the issue completely. Machine
still functions well as a file/web/postgresql dev server so it's all
good.
tanks!
next prev parent reply other threads:[~2018-09-26 23:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-23 20:07 Rob Prowel
2018-09-23 21:19 ` Thomas Gleixner
2018-09-23 21:54 ` Rob Prowel
2018-09-24 6:23 ` Thomas Gleixner
2018-09-24 14:01 ` Rob Prowel
2018-09-26 23:38 ` Rob Prowel [this message]
2018-09-27 15:04 ` Thomas Gleixner
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