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From: Thomas Monjalon <thomas@monjalon.net>
To: Rongwei Liu <rongweil@nvidia.com>,
	Jerin Jacob <jerinjacobk@gmail.com>,
	Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Cc: dev@dpdk.org, matan@nvidia.com, viacheslavo@nvidia.com,
	orika@nvidia.com,  stephen@networkplumber.org,
	rasland@nvidia.com, Ferruh Yigit <ferruh.yigit@amd.com>,
	bruce.richardson@intel.com
Subject: Re: [PATCH v4 2/3] ethdev: add standby state for live migration
Date: Wed, 01 Feb 2023 09:31:26 +0100	[thread overview]
Message-ID: <2615033.BddDVKsqQX@thomas> (raw)
In-Reply-To: <6b2c3d11-428a-2c69-ddf9-2b3306dacbce@oktetlabs.ru>

01/02/2023 08:32, Andrew Rybchenko:
> On 2/1/23 01:55, Thomas Monjalon wrote:
> > 31/01/2023 19:14, Jerin Jacob:
> >> On Wed, Jan 18, 2023 at 9:15 PM Rongwei Liu <rongweil@nvidia.com> wrote:
> >>>
> >>> When a DPDK application must be upgraded,
> >>> the traffic downtime should be shortened as much as possible.
> >>> During the migration time, the old application may stay alive
> >>> while the new application is starting and being configured.
> >>>
> >>> In order to optimize the switch to the new application,
> >>> the old application may need to be aware of the presence
> >>> of the new application being prepared.
> >>> This is achieved with a new API allowing the user to change the
> >>> new application state to standby and active later.
> >>>
> >>> The added function is trying to apply the new state to all probed
> >>> ethdev ports. To make this API simple and easy to use,
> >>> the same flags have to be accepted by all devices.
> >>>
> >>> This is the scenario of operations in the old and new applications:
> >>> .       device: already configured by the old application
> >>> .       new:    start as active
> >>> .       new:    probe the same device
> >>
> >> How to probe same device if is already bind to another application?
> >> vfio-pci wont allow this.
> > 
> > I missed that part.
> > There is no way to share a VFIO device between 2 applications?
> 
> As I understand multi-process shares an VFIO device between
> many application. As far as I remember it is just required to
> pass corresponding file descriptor to another application.
> 
> Anyway I fully agree that the patch requires more documentation
> in doc/guides/ with the description of live migration theory of
> operations.

Yes that part is missing.
Rongwei, you should try a fake migration with e1000 or virtio
(both available in QEMU), so you can play with VFIO device probing.

> >>> .       new:    set as standby
> >>> .       new:    configure the device
> >>> .       device: has configurations from old and new applications
> >>> .       old:    clear its device configuration
> >>> .       device: has only 1 configuration from new application
> >>> .       new:    set as active
> >>> .       device: downtime for connecting all to the new application
> >>> .       old:    shutdown




  reply	other threads:[~2023-02-01  8:31 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-01  8:20 [RFC 0/2] add API to set process to primary or secondary Rongwei Liu
2022-12-01  8:20 ` [RFC 1/2] ethdev: add group description Rongwei Liu
2022-12-01  8:20 ` [RFC 2/2] ethdev: add API to set process to primary or secondary Rongwei Liu
2022-12-01 15:10   ` Stephen Hemminger
2022-12-02  3:27     ` Rongwei Liu
2022-12-05 16:08       ` Stephen Hemminger
2022-12-06  3:47         ` Rongwei Liu
2022-12-06  5:54           ` Stephen Hemminger
2022-12-21  9:00             ` [RFC v3 0/2] add API to set process to active or standby Rongwei Liu
2022-12-21  9:00               ` [RFC v3 1/2] ethdev: add group description Rongwei Liu
2023-01-18 15:44                 ` [PATCH v4 0/3] add API for live migration Rongwei Liu
2023-01-18 15:44                   ` [PATCH v4 1/3] ethdev: add flow rule group description Rongwei Liu
2023-01-31 11:53                     ` Ori Kam
2023-02-06 12:15                       ` Rongwei Liu
2023-02-07  2:57                     ` [PATCH v5] " Rongwei Liu
2023-02-08 20:28                       ` Ferruh Yigit
2023-02-09  2:06                         ` Rongwei Liu
2023-02-09  7:32                         ` [PATCH v6] " Rongwei Liu
2023-02-09  8:01                           ` Ori Kam
2023-02-09 11:26                             ` Ferruh Yigit
2023-01-18 15:44                   ` [PATCH v4 2/3] ethdev: add standby state for live migration Rongwei Liu
2023-01-31 13:50                     ` Ori Kam
2023-01-31 18:14                     ` Jerin Jacob
2023-01-31 22:55                       ` Thomas Monjalon
2023-02-01  7:32                         ` Andrew Rybchenko
2023-02-01  8:31                           ` Thomas Monjalon [this message]
2023-02-01  8:40                           ` Jerin Jacob
2023-02-01  8:46                             ` Thomas Monjalon
2023-02-02 10:23                               ` Rongwei Liu
2023-02-01  7:52                     ` Andrew Rybchenko
2023-02-01  8:27                       ` Thomas Monjalon
2023-02-01  8:40                         ` Andrew Rybchenko
2023-01-18 15:44                   ` [PATCH v4 3/3] ethdev: add standby flags " Rongwei Liu
2023-01-23 13:20                     ` Jerin Jacob
2023-01-30  2:47                       ` Rongwei Liu
2023-01-30 17:10                         ` Jerin Jacob
2023-01-31  2:53                           ` Rongwei Liu
2023-01-31  8:45                             ` Jerin Jacob
2023-01-31  9:01                               ` Rongwei Liu
2023-01-31 14:37                                 ` Jerin Jacob
2023-01-31 14:45                                   ` Ori Kam
2023-01-31 17:50                                     ` Thomas Monjalon
2023-01-31 18:10                                       ` Jerin Jacob
2022-12-21  9:00               ` [RFC v3 2/2] ethdev: add API to set process to active or standby Rongwei Liu
2022-12-21  9:12                 ` Jerin Jacob
2022-12-21  9:32                   ` Rongwei Liu
2022-12-21 10:59                     ` Jerin Jacob
2022-12-21 12:05                       ` Rongwei Liu
2022-12-21 12:44                         ` Jerin Jacob
2022-12-21 12:50                           ` Rongwei Liu
2022-12-21 13:12                             ` Jerin Jacob
2022-12-21 14:33                               ` Rongwei Liu
2022-12-26 16:44                                 ` Ori Kam
2023-01-15 22:46                                   ` Thomas Monjalon

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