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Subject: Re: [PATCH] PCI/LINK: Account for BW notification in vector
 calculation
To:     Alex Williamson <alex.williamson@redhat.com>
Cc:     bhelgaas@google.com, helgaas@kernel.org, linux-pci@vger.kernel.org,
        austin_bolen@dell.com, alex_gagniuc@dellteam.com,
        keith.busch@intel.com, Shyam_Iyer@Dell.com, lukas@wunner.de,
        okaya@kernel.org, torvalds@linux-foundation.org,
        linux-kernel@vger.kernel.org
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From:   Alex G <mr.nuke.me@gmail.com>
Message-ID: <84300da7-9bbd-4f32-c7fa-23724db60b88@gmail.com>
Date:   Tue, 23 Apr 2019 09:33:53 -0500
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On 4/22/19 7:33 PM, Alex Williamson wrote:
> On Mon, 22 Apr 2019 19:05:57 -0500
> Alex G <mr.nuke.me@gmail.com> wrote:
>> echo 0000:07:00.0:pcie010 |
>> sudo tee /sys/bus/pci_express/drivers/pcie_bw_notification/unbind
> 
> That's a bad solution for users, this is meaningless tracking of a
> device whose driver is actively managing the link bandwidth for power
> purposes. 

0.5W savings on a 100+W GPU? I agree it's meaningless.

> There is nothing wrong happening here that needs to fill
> logs.  I thought maybe if I enabled notification of autonomous
> bandwidth changes that it might categorize these as something we could
> ignore, but it doesn't.
> How can we identify only cases where this is
> an erroneous/noteworthy situation?  Thanks,

You don't. Ethernet doesn't. USB doesn't. This logging behavior is 
consistent with every other subsystem that deals with multi-speed links. 
I realize some people are very resistant to change (and use very ancient 
kernels). I do not, however, agree that this is a sufficient argument to 
dis-unify behavior.

Alex