netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Jason Gunthorpe <jgg@nvidia.com>
To: David Ahern <dsahern@gmail.com>
Cc: Parav Pandit <parav@nvidia.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	Jiri Pirko <jiri@nvidia.com>,
	"dledford@redhat.com" <dledford@redhat.com>,
	Leon Romanovsky <leonro@nvidia.com>,
	Saeed Mahameed <saeedm@nvidia.com>,
	"kuba@kernel.org" <kuba@kernel.org>,
	"davem@davemloft.net" <davem@davemloft.net>,
	Vu Pham <vuhuong@nvidia.com>
Subject: Re: [PATCH net-next 03/13] devlink: Support add and delete devlink port
Date: Wed, 18 Nov 2020 16:42:26 -0400	[thread overview]
Message-ID: <20201118204226.GB917484@nvidia.com> (raw)
In-Reply-To: <ac0c5a69-06e4-3809-c778-b27d6e437ed5@gmail.com>

On Wed, Nov 18, 2020 at 12:36:26PM -0700, David Ahern wrote:
> On 11/18/20 11:38 AM, Jason Gunthorpe wrote:
> > On Wed, Nov 18, 2020 at 11:03:24AM -0700, David Ahern wrote:
> > 
> >> With Connectx-4 Lx for example the netdev can have at most 63 queues
> > 
> > What netdev calls a queue is really a "can the device deliver
> > interrupts and packets to a given per-CPU queue" and covers a whole
> > spectrum of smaller limits like RSS scheme, # of available interrupts,
> > ability of the device to create queues, etc.
> > 
> > CX4Lx can create a huge number of queues, but hits one of these limits
> > that mean netdev's specific usage can't scale up. Other stuff like
> > RDMA doesn't have the same limits, and has tonnes of queues.
> > 
> > What seems to be needed is a resource controller concept like cgroup
> > has for processes. The system is really organized into a tree:
> > 
> >            physical device
> >               mlx5_core
> >         /      |      \      \                        (aux bus)
> >      netdev   rdma    vdpa   SF  etc
> >                              |                        (aux bus)
> >                            mlx5_core
> >                           /      \                    (aux bus)
> >                        netdev   vdpa
> > 
> > And it does make a lot of sense to start to talk about limits at each
> > tree level.
> > 
> > eg the top of the tree may have 128 physical interrupts. With 128 CPU
> > cores that isn't enough interrupts to support all of those things
> > concurrently.
> > 
> > So the user may want to configure:
> >  - The first level netdev only gets 64,
> >  - 3rd level mlx5_core gets 32 
> >  - Final level vdpa gets 8
> > 
> > Other stuff has to fight it out with the remaining shared interrupts.
> > 
> > In netdev land # of interrupts governs # of queues
> > 
> > For RDMA # of interrupts limits the CPU affinities for queues
> > 
> > VPDA limits the # of VMs that can use VT-d
> > 
> > The same story repeats for other less general resources, mlx5 also
> > has consumption of limited BAR space, and consumption of some limited
> > memory elements. These numbers are much bigger and may not need
> > explicit governing, but the general concept holds.
> > 
> > It would be very nice if the limit could be injected when the aux
> > device is created but before the driver is bound. I'm not sure how to
> > manage that though..
> > 
> > I assume other devices will be different, maybe some devices have a
> > limit on the number of total queues, or a limit on the number of
> > VDPA or RDMA devices.
> 
> A lot of low level resource details that need to be summarized into a
> nicer user / config perspective to specify limits / allocations.

Well, now that we have the aux bus stuff there is a nice natural place
to put things..

The aux bus owner device (mlx5_core) could have a list of available
resources

Each aux bus device (netdev/rdma/vdpa) could have a list of consumed
resources

Some API to place a limit on the consumed resources at each aux bus
device.

The tricky bit is the auto-probing/configure. By the time the user has
a chance to apply a limit the drivers are already bound and have
already done their setup. So each subsystem has to support dynamically
imposing a limit..

And I simplified things a bit above too, we actually have two kinds of
interrupt demand: sharable and dedicated. The actual need is to carve
out a bunch of dedicated interrupts and only allow subsystems that are
doing VT-d guest interrupt assignment to consume them (eg VDPA)

Jason

  reply	other threads:[~2020-11-18 20:42 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12 19:24 [PATCH net-next 00/13] Add mlx5 subfunction support Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 01/13] devlink: Prepare code to fill multiple port function attributes Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 02/13] devlink: Introduce PCI SF port flavour and port attribute Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 03/13] devlink: Support add and delete devlink port Parav Pandit
2020-11-18 16:21   ` David Ahern
2020-11-18 17:02     ` Parav Pandit
2020-11-18 18:03       ` David Ahern
2020-11-18 18:38         ` Jason Gunthorpe
2020-11-18 19:36           ` David Ahern
2020-11-18 20:42             ` Jason Gunthorpe [this message]
2020-11-18 19:22         ` Parav Pandit
2020-11-19  0:41           ` Jacob Keller
2020-11-19  1:17             ` David Ahern
2020-11-19  1:56               ` Samudrala, Sridhar
2020-11-19  0:52       ` Jacob Keller
2020-11-12 19:24 ` [PATCH net-next 04/13] devlink: Support get and set state of port function Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 05/13] devlink: Avoid global devlink mutex, use per instance reload lock Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 06/13] devlink: Introduce devlink refcount to reduce scope of global devlink_mutex Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 07/13] net/mlx5: SF, Add auxiliary device support Parav Pandit
2020-12-07  2:48   ` David Ahern
2020-12-07  4:53     ` Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 08/13] net/mlx5: SF, Add auxiliary device driver Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 09/13] net/mlx5: E-switch, Prepare eswitch to handle SF vport Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 10/13] net/mlx5: E-switch, Add eswitch helpers for " Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 11/13] net/mlx5: SF, Add SF configuration hardware commands Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 12/13] net/mlx5: SF, Add port add delete functionality Parav Pandit
2020-11-12 19:24 ` [PATCH net-next 13/13] net/mlx5: SF, Port function state change support Parav Pandit
2020-11-16 22:52 ` [PATCH net-next 00/13] Add mlx5 subfunction support Jakub Kicinski
2020-11-17  0:06   ` Saeed Mahameed
2020-11-17  1:58     ` Jakub Kicinski
2020-11-17  4:08       ` Parav Pandit
2020-11-17 17:11         ` Jakub Kicinski
2020-11-17 18:49           ` Jason Gunthorpe
2020-11-19  2:14             ` Jakub Kicinski
2020-11-19  4:35               ` David Ahern
2020-11-19  5:57                 ` Saeed Mahameed
2020-11-20  1:31                   ` Jakub Kicinski
2020-11-25  5:33                   ` David Ahern
2020-11-25  6:00                     ` Parav Pandit
2020-11-25 14:37                       ` David Ahern
2020-11-20  1:29                 ` Jakub Kicinski
2020-11-20 17:58                   ` Alexander Duyck
2020-11-20 19:04                     ` Samudrala, Sridhar
2020-11-23 21:51                       ` Saeed Mahameed
2020-11-24  7:01                       ` Jason Wang
2020-11-24  7:05                         ` Jason Wang
2020-11-19  6:12               ` Saeed Mahameed
2020-11-19  8:25                 ` Parav Pandit
2020-11-20  1:35                 ` Jakub Kicinski
2020-11-20  3:34                   ` Parav Pandit
2020-11-17 18:50           ` Parav Pandit
2020-11-19  2:23             ` Jakub Kicinski
2020-11-19  6:22               ` Saeed Mahameed
2020-11-19 14:00                 ` Jason Gunthorpe
2020-11-20  3:35                   ` Jakub Kicinski
2020-11-20  3:50                     ` Parav Pandit
2020-11-20 16:16                     ` Jason Gunthorpe

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=20201118204226.GB917484@nvidia.com \
    --to=jgg@nvidia.com \
    --cc=davem@davemloft.net \
    --cc=dledford@redhat.com \
    --cc=dsahern@gmail.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=jiri@nvidia.com \
    --cc=kuba@kernel.org \
    --cc=leonro@nvidia.com \
    --cc=linux-rdma@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=parav@nvidia.com \
    --cc=saeedm@nvidia.com \
    --cc=vuhuong@nvidia.com \
    --subject='Re: [PATCH net-next 03/13] devlink: Support add and delete devlink port' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).