From: Bjorn Helgaas <helgaas@kernel.org>
To: Alexandru Gagniuc <mr.nuke.me@gmail.com>,
Alexandru Gagniuc <alex_gagniuc@dellteam.com>,
Keith Busch <keith.busch@intel.com>
Cc: Jan Vesely <jano.vesely@gmail.com>,
Lukas Wunner <lukas@wunner.de>,
Alex Williamson <alex.williamson@redhat.com>,
Austin Bolen <austin_bolen@dell.com>,
Shyam Iyer <Shyam_Iyer@dell.com>, Sinan Kaya <okaya@kernel.org>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Issues with "PCI/LINK: Report degraded links via link bandwidth notification"
Date: Wed, 15 Jan 2020 16:10:08 -0600 [thread overview]
Message-ID: <20200115221008.GA191037@google.com> (raw)
I think we have a problem with link bandwidth change notifications
(see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/pcie/bw_notification.c).
Here's a recent bug report where Jan reported "_tons_" of these
notifications on an nvme device:
https://bugzilla.kernel.org/show_bug.cgi?id=206197
There was similar discussion involving GPU drivers at
https://lore.kernel.org/r/20190429185611.121751-2-helgaas@kernel.org
The current solution is the CONFIG_PCIE_BW config option, which
disables the messages completely. That option defaults to "off" (no
messages), but even so, I think it's a little problematic.
Users are not really in a position to figure out whether it's safe to
enable. All they can do is experiment and see whether it works with
their current mix of devices and drivers.
I don't think it's currently useful for distros because it's a
compile-time switch, and distros cannot predict what system configs
will be used, so I don't think they can enable it.
Does anybody have proposals for making it smarter about distinguishing
real problems from intentional power management, or maybe interfaces
drivers could use to tell us when we should ignore bandwidth changes?
Bjorn
next reply other threads:[~2020-01-15 22:10 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 22:10 Bjorn Helgaas [this message]
2020-01-16 2:44 ` Issues with "PCI/LINK: Report degraded links via link bandwidth notification" Alex G
2020-01-18 0:18 ` Bjorn Helgaas
2020-01-20 2:33 ` Bjorn Helgaas
2020-01-20 15:56 ` Alex Williamson
2020-01-20 16:01 ` Alex G.
2020-01-21 11:10 ` Lucas Stach
2020-01-21 14:55 ` Alex G.
2020-02-03 1:56 ` Dave Airlie
2020-02-03 2:04 ` Dave Airlie
2020-02-03 2:07 ` Ben Skeggs
2020-02-03 21:16 ` Alex Deucher
2020-02-04 4:38 ` Lukas Wunner
2020-02-04 14:47 ` Alex Deucher
2020-01-30 16:26 ` Christoph Hellwig
2020-02-22 16:58 ` Bjorn Helgaas
2021-01-28 23:39 ` Bjorn Helgaas
2021-01-28 23:51 ` Sinan Kaya
2021-01-29 0:07 ` Alex G.
2021-01-29 21:56 ` Bjorn Helgaas
2021-02-02 19:50 ` Alex G.
2021-02-02 20:16 ` Bjorn Helgaas
2021-02-02 20:25 ` Alex G.
2021-01-29 1:30 ` Alex Deucher
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200115221008.GA191037@google.com \
--to=helgaas@kernel.org \
--cc=Shyam_Iyer@dell.com \
--cc=alex.williamson@redhat.com \
--cc=alex_gagniuc@dellteam.com \
--cc=austin_bolen@dell.com \
--cc=jano.vesely@gmail.com \
--cc=keith.busch@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lukas@wunner.de \
--cc=mr.nuke.me@gmail.com \
--cc=okaya@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.