Message-ID: <5433BE1B.5020703@imc.nl>
Date:	Tue, 7 Oct 2014 12:19:07 +0200
From:	Adrian Vasile <adrian.vasile@....nl>
To:	Alex <xor@....bz>, <linux-kernel@...r.kernel.org>
Subject: Re: TSC Problems (warp between CPUs)

Alex,

Have you managed to fix this issue? I'm seeing the same on an Asus X99
Deluxe board with both 5930K and 5960X and the latest BIOS as of today
(0904).
I had some hopes of linux-3.17 working around this but it did not help.
Asus support is disappointing, I don't think they will ever fix this.

I'm wondering if it's worth trying a different motherboard, any
recommendations?

Thank you.

Regards,
Adrian

On 31/12/13 22:24, Alex wrote:
> A Happy new year to all :)
>
> Just wondering whether anyone has any ideas on how I could force the
> TSC to resync?
>
> Starting to get a bit desperate. The motherboard manufacturers support
> is useless.... They keep telling me to install Windows *groan*. I dont
> think there is any easy way to expose what clock source the OS is
> using even in windows.
>
> I even tried firing an email at the AmiBios guys. I think I have
> exhausted every avenue of help as far as the hardware goes.
>
> Any suggestions?
>
> Kind regards,
> Alex
>
> On 2013-12-29 11:21, Alex wrote:
>> On 2013-12-29 01:35, One Thousand Gnomes wrote:
>>>> not guaranteed to be precise. For example a SMI (System Management
>>>> Interrupt) could interrupt the software flow that is attempting to
>>>> write
>>>> the time-stamp counter immediately prior to the WRMSR. This could mean
>>>> the value written to the TSC could vary by thousands to millions of
>>>> clocks.
>>>
>>> Yes SMI is a disaster area for any real time activity (and many other
>>> things ;) ), but many systems actually make little use of it,
>>> especially
>>> once the USB is owned by the OS.
>>>
>>> For synchronization you can retry the sync if it isn't within an
>>> acceptable range. The odds of getting an SMI mid sync setup should be
>>> very very low, so the odds of repeating the failure several times
>>> should
>>> be negligible and after a few tries you could give up and assume the
>>> hardware is buggered then fall back to HPET.
>>
>> Hi Alan,
>>
>> The sync retry sounds like an interesting strategy but is outside my
>> knowledge
>> scope as a regular end user (I do have a reasonable understanding of
>> C and can patch+
>> recompile) but I lack the architecture knowledge to implement a patch
>> to do this.
>>
>> Any suggestions?
>

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