From: Bjorn Helgaas <helgaas@kernel.org>
To: Alexander Duyck <alexander.duyck@gmail.com>,
Keith Busch <kbusch@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>, Leon Romanovsky <leon@kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Saeed Mahameed <saeedm@nvidia.com>,
Jakub Kicinski <kuba@kernel.org>,
linux-pci <linux-pci@vger.kernel.org>,
linux-rdma@vger.kernel.org, Netdev <netdev@vger.kernel.org>,
Don Dutile <ddutile@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>,
"David S . Miller" <davem@davemloft.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH mlx5-next v7 0/4] Dynamically assign MSI-X vectors count
Date: Mon, 29 Mar 2021 20:29:49 -0500 [thread overview]
Message-ID: <20210330012949.GA1205505@bjorn-Precision-5520> (raw)
In-Reply-To: <20210326190148.GN2710221@ziepe.ca>
On Fri, Mar 26, 2021 at 04:01:48PM -0300, Jason Gunthorpe wrote:
> On Fri, Mar 26, 2021 at 11:50:44AM -0700, Alexander Duyck wrote:
>
> > My concern would be that we are defining the user space interface.
> > Once we have this working as a single operation I could see us having
> > to support it that way going forward as somebody will script something
> > not expecting an "offline" sysfs file, and the complaint would be that
> > we are breaking userspace if we require the use of an "offline"
> > file.
>
> Well, we wouldn't do that. The semantic we define here is that the
> msix_count interface 'auto-offlines' if that is what is required. If
> we add some formal offline someday then 'auto-offline' would be a NOP
> when the device is offline and do the same online/offline sequence as
> today if it isn't.
Alexander, Keith, any more thoughts on this?
I think I misunderstood Greg's subdirectory comment. We already have
directories like this:
/sys/bus/pci/devices/0000:01:00.0/link/
/sys/bus/pci/devices/0000:01:00.0/msi_irqs/
/sys/bus/pci/devices/0000:01:00.0/power/
and aspm_ctrl_attr_group (for "link") is nicely done with static
attributes. So I think we could do something like this:
/sys/bus/pci/devices/0000:01:00.0/ # PF directory
sriov/ # SR-IOV related stuff
vf_total_msix
vf_msix_count_BB:DD.F # includes bus/dev/fn of first VF
...
vf_msix_count_BB:DD.F # includes bus/dev/fn of last VF
And I think this could support the mlx5 model as well as the NVMe
model.
For NVMe, a write to vf_msix_count_* would have to auto-offline the VF
before asking the PF to assign the vectors, as Jason suggests above.
Before VF Enable is set, the vf_msix_count_* files wouldn't exist and
we wouldn't be able to assign vectors to VFs; IIUC that's a difference
from the NVMe interface, but maybe not a terrible one?
I'm not proposing changing nvme-cli to use this, but if the interface
is general enough to support both, that would be a good clue that it
might be able to support future devices with similar functionality.
Bjorn
next prev parent reply other threads:[~2021-03-30 1:30 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 7:55 [PATCH mlx5-next v7 0/4] Dynamically assign MSI-X vectors count Leon Romanovsky
2021-03-01 7:55 ` [PATCH mlx5-next v7 1/4] PCI: Add a sysfs file to change the MSI-X table size of SR-IOV VFs Leon Romanovsky
2021-03-01 8:14 ` Greg Kroah-Hartman
2021-03-01 8:32 ` Leon Romanovsky
2021-03-01 8:37 ` Greg Kroah-Hartman
2021-03-01 8:53 ` Leon Romanovsky
2021-03-01 7:55 ` [PATCH mlx5-next v7 2/4] net/mlx5: Add dynamic MSI-X capabilities bits Leon Romanovsky
2021-03-01 7:55 ` [PATCH mlx5-next v7 3/4] net/mlx5: Dynamically assign MSI-X vectors count Leon Romanovsky
2021-03-01 7:55 ` [PATCH mlx5-next v7 4/4] net/mlx5: Implement sriov_get_vf_total_msix/count() callbacks Leon Romanovsky
2021-03-07 8:11 ` [PATCH mlx5-next v7 0/4] Dynamically assign MSI-X vectors count Leon Romanovsky
2021-03-07 18:55 ` Alexander Duyck
2021-03-07 19:19 ` Leon Romanovsky
2021-03-08 16:33 ` Alexander Duyck
2021-03-08 19:20 ` Leon Romanovsky
2021-03-10 19:09 ` Bjorn Helgaas
2021-03-10 20:10 ` Leon Romanovsky
2021-03-10 20:21 ` Greg Kroah-Hartman
2021-03-11 8:37 ` Leon Romanovsky
2021-03-10 23:34 ` Alexander Duyck
2021-03-11 18:17 ` Bjorn Helgaas
2021-03-11 19:16 ` Keith Busch
2021-03-11 19:21 ` Leon Romanovsky
2021-03-11 20:22 ` Jason Gunthorpe
2021-03-11 20:50 ` Keith Busch
2021-03-11 21:44 ` Jason Gunthorpe
2021-03-25 17:21 ` Bjorn Helgaas
2021-03-25 17:36 ` Jason Gunthorpe
2021-03-25 18:20 ` Bjorn Helgaas
2021-03-25 18:28 ` Jason Gunthorpe
2021-03-26 6:44 ` Leon Romanovsky
2021-03-26 16:00 ` Alexander Duyck
2021-03-26 16:56 ` Jason Gunthorpe
2021-03-26 17:08 ` Bjorn Helgaas
2021-03-26 17:12 ` Jason Gunthorpe
2021-03-27 6:00 ` Leon Romanovsky
2021-03-26 17:29 ` Keith Busch
2021-03-26 17:31 ` Jason Gunthorpe
2021-03-26 18:50 ` Alexander Duyck
2021-03-26 19:01 ` Jason Gunthorpe
2021-03-30 1:29 ` Bjorn Helgaas [this message]
2021-03-30 13:57 ` Jason Gunthorpe
2021-03-30 15:00 ` Bjorn Helgaas
2021-03-30 19:47 ` Jason Gunthorpe
2021-03-30 20:41 ` Bjorn Helgaas
2021-03-30 22:43 ` Jason Gunthorpe
2021-03-31 6:38 ` Greg Kroah-Hartman
2021-03-31 12:19 ` Jason Gunthorpe
2021-03-31 15:03 ` Greg Kroah-Hartman
2021-03-31 17:07 ` Jason Gunthorpe
2021-03-31 4:08 ` Leon Romanovsky
2021-04-01 1:23 ` Bjorn Helgaas
2021-04-01 11:49 ` Leon Romanovsky
2021-03-30 18:10 ` Keith Busch
2021-03-26 19:36 ` Bjorn Helgaas
2021-03-27 12:38 ` Greg Kroah-Hartman
2021-03-25 18:31 ` Keith Busch
2021-03-25 18:36 ` Jason Gunthorpe
2021-03-11 19:17 ` Leon Romanovsky
2021-03-11 19:37 ` Alexander Duyck
2021-03-11 19:51 ` Leon Romanovsky
2021-03-11 20:11 ` Alexander Duyck
2021-03-11 20:19 ` Jason Gunthorpe
2021-03-11 21:49 ` Alexander Duyck
2021-03-11 23:20 ` Jason Gunthorpe
2021-03-12 2:53 ` Alexander Duyck
2021-03-12 6:32 ` Leon Romanovsky
2021-03-12 16:59 ` Alexander Duyck
2021-03-12 17:03 ` Jason Gunthorpe
2021-03-12 18:34 ` Leon Romanovsky
2021-03-12 18:41 ` Leon Romanovsky
2021-03-12 13:00 ` Jason Gunthorpe
2021-03-12 13:36 ` Keith Busch
2021-03-11 20:31 ` Jason Gunthorpe
2021-03-10 5:58 ` Leon Romanovsky
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