From: Bodong Wang <bodong@mellanox.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: <bhelgaas@google.com>, <linux-pci@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <saeedm@mellanox.com>,
Eli Cohen <eli@mellanox.com>
Subject: Re: [v2] PCI: Add an option to control probing of VFs before enabling SR-IOV
Date: Wed, 12 Apr 2017 09:34:46 -0500 [thread overview]
Message-ID: <11a16b75-8f70-1135-a326-52fb6f31cebc@mellanox.com> (raw)
In-Reply-To: <20170411211211.GB14778@bhelgaas-glaptop.roam.corp.google.com>
[-- Attachment #1: Type: text/plain, Size: 1897 bytes --]
On 4/11/2017 4:12 PM, Bjorn Helgaas wrote:
> Hi Bodong,
>
> On Wed, Mar 22, 2017 at 05:53:58PM +0200, bodong@mellanox.com wrote:
>> From: Bodong Wang <bodong@mellanox.com>
>>
>> Sometimes it is not desirable to probe the virtual functions after
>> SRIOV is enabled. This can save host side resource usage by VF
>> instances which would be eventually probed to VMs.
>>
>> Add a new PCI sysfs interface "sriov_probe_vfs" to control that
>> from the PF, all current callers still retain the same functionality.
>> To modify it, echo 0/n/N (disable probe) or 1/y/Y (enable probe) to
>>
>> /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_probe_vfs
> Is this basically the same functionality as /sys/bus/pci/drivers_autoprobe,
> but limited to a specific PF? I.e., could we accomplish the same thing
> with the following?
>
> # echo 0 > /sys/bus/pci/devices/DDDD:BB:dd.f/sriov_numvfs
> # echo 0 > /sys/bus/pci/drivers_autoprobe
> # echo 2 > /sys/bus/pci/devices/DDDD:BB:dd.f/sriov_numvfs
> # echo 1 > /sys/bus/pci/drivers_autoprobe
>
> If not, can you contrast the above with drivers_autoprobe? If we need
> both, should they be named more similarly?
Hi Bjorn,
I agree with Alex about not using driver_autoprobe to achieve this. It
will affect all pci related device once it's disabled(probably in a bad
way). On the other hand, current pci driver doesn't work for this use
case at all. VFs drivers(if any) will be probed once sriov is enabled no
matter what. The code path is /pci_enable_sriov//->
//pci_bus_add_device->device_attach/, and drivers will be probed at the
end. Drivers_autoprobe only prevents probing /pci_device_add /is
called/. /This patch bounded the change to the device itself and
requires no device driver update.
For the name convention, it's aligned with other sriov related sysfs
entries. Let me know if you have better options.
Thanks,
Bodong
[-- Attachment #2: Type: text/html, Size: 2733 bytes --]
next prev parent reply other threads:[~2017-04-12 14:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-22 15:53 [v2] PCI: Add an option to control probing of VFs before enabling SR-IOV bodong
2017-03-27 15:11 ` Bodong Wang
2017-03-31 15:07 ` Bodong Wang
2017-04-11 21:12 ` Bjorn Helgaas
2017-04-11 21:51 ` Alex Williamson
2017-04-12 14:34 ` Bodong Wang [this message]
2017-04-12 14:37 ` Bodong Wang
2017-04-12 15:22 ` Bjorn Helgaas
2017-04-12 16:00 ` Bodong Wang
2017-04-11 21:51 ` Alex Williamson
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=11a16b75-8f70-1135-a326-52fb6f31cebc@mellanox.com \
--to=bodong@mellanox.com \
--cc=bhelgaas@google.com \
--cc=eli@mellanox.com \
--cc=helgaas@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=saeedm@mellanox.com \
/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.