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From: Bjorn Helgaas <bhelgaas@google.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Greg KH <greg@kroah.com>,
	kernel list <linux-kernel@vger.kernel.org>,
	Joe Lawrence <joe.lawrence@stratus.com>,
	Myron Stowe <myron.stowe@redhat.com>,
	Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Bruce Allan <bruce.w.allan@intel.com>,
	Carolyn Wyborny <carolyn.wyborny@intel.com>,
	Don Skidmore <donald.c.skidmore@intel.com>,
	Greg Rose <gregory.v.rose@intel.com>,
	Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>,
	Alex Duyck <alexander.h.duyck@intel.com>,
	John Ronciak <john.ronciak@intel.com>,
	Tushar Dave <tushar.n.dave@intel.com>,
	"e1000-devel@lists.sourceforge.net" 
	<e1000-devel@lists.sourceforge.net>
Subject: Re: /sys/module/pcie_aspm/parameters/policy not writable?
Date: Fri, 2 Aug 2013 07:48:37 -0600	[thread overview]
Message-ID: <CAErSpo5dUEO8UX650Y=tx9Wp-w27k6JWU3WKpUPxiiV-tUULiw@mail.gmail.com> (raw)
In-Reply-To: <20130802021259.GA3715@amd.pavel.ucw.cz>

On Thu, Aug 1, 2013 at 8:13 PM, Pavel Machek <pavel@ucw.cz> wrote:

> Hmm. So I've update bios using 7buj28uc.iso . Reverted the patches and
> yes, ping latencies are still bad:

Wow.  I can hardly believe how bad this is (assuming Windows has the
same problem).  Thanks a lot for checking this out.

>> >> Carolyn's patch will likely work, at least most of the time, but I
>> >> think there's a small possibility that it could cause a conflict
>> >> between the BIOS and the OS over ASPM control, so I'm not 100% in
>> >> support of that approach.  A conflict may not happen on your
>> >> machine,
>> >
>> > Can we base it on DMI  whitelist?
>>
>> I don't think we can know a priori whether a machine (even your
>> machine) is susceptible to a conflict.  But if Carolyn forcibly
>
> We don't apriori now how broken machines are, true. There are 1000
> ways BIOS can break things. And yes, it will be us breaking the specs
> here. But "useful machine with OS breaking specs" is better than
> "machine useless for ssh".
>
> _If_ there's a conflict, we can try something else.
>
> (Has someone really seen a conflict, or is it just theoretical thing?)

Completely theoretical, as far as I know.  I don't even know what a
conflict would look like.  Maybe some unexpected ASPM enable/disable
from SMM during suspend/resume or something.  Things like that would
likely go unnoticed anyway.

Bjorn

  reply	other threads:[~2013-08-02 13:49 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-09  1:26 /sys/module/pcie_aspm/parameters/policy not writable? Pavel Machek
2013-07-09  4:13 ` Greg KH
2013-07-09  9:14   ` Pavel Machek
2013-07-09  9:49   ` Pavel Machek
2013-07-09 10:10     ` Pavel Machek
2013-07-09 16:25       ` Bjorn Helgaas
2013-07-10 13:29         ` Pavel Machek
2013-07-10 19:57           ` Bjorn Helgaas
2013-07-10 22:21             ` Wyborny, Carolyn
2013-07-10 22:57               ` Bjorn Helgaas
2013-07-10 22:57                 ` Bjorn Helgaas
2013-07-11 17:45                 ` Wyborny, Carolyn
2013-07-11 17:45                   ` Wyborny, Carolyn
2013-07-12 11:52                 ` Pavel Machek
2013-07-12 11:52                   ` Pavel Machek
2013-07-12 11:03             ` Pavel Machek
2013-07-12 11:11             ` Pavel Machek
2013-07-19 17:46               ` Bjorn Helgaas
2013-07-24 15:19                 ` Wyborny, Carolyn
2013-07-28 13:51                   ` Pavel Machek
2013-08-01 14:55                     ` Wyborny, Carolyn
2013-08-01 15:55                     ` Wyborny, Carolyn
2013-08-02  0:39                       ` Pavel Machek
2013-08-02 14:58                         ` Wyborny, Carolyn
2013-07-31 23:53                 ` Bjorn Helgaas
2013-08-01 14:57                   ` Wyborny, Carolyn
2013-08-01 19:33                     ` Bjorn Helgaas
2013-08-01 20:00                   ` Pavel Machek
2013-08-01 20:27                     ` Bjorn Helgaas
2013-08-02  1:02                       ` Pavel Machek
2013-08-02  2:13                       ` Pavel Machek
2013-08-02 13:48                         ` Bjorn Helgaas [this message]
2013-08-01  6:19             ` Jeff Kirsher
2013-07-09 16:37     ` Greg KH
2013-07-09 17:15       ` Pavel Machek
2013-07-10  4:24     ` Robert Hancock

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