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From: Jason Gunthorpe <jgg@nvidia.com>
To: Avihai Horon <avihaih@nvidia.com>
Cc: qemu-devel@nongnu.org,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Cédric Le Goater" <clg@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Joao Martins" <joao.m.martins@oracle.com>,
	"Yishai Hadas" <yishaih@nvidia.com>,
	"Maor Gottlieb" <maorg@nvidia.com>,
	"Kirti Wankhede" <kwankhede@nvidia.com>,
	"Tarun Gupta" <targupta@nvidia.com>
Subject: Re: [PATCH for-8.2 0/6] vfio/migration: Add P2P support for VFIO migration
Date: Tue, 18 Jul 2023 12:46:01 -0300	[thread overview]
Message-ID: <ZLazufgTjVliQ9mJ@nvidia.com> (raw)
In-Reply-To: <20230716081541.27900-1-avihaih@nvidia.com>

On Sun, Jul 16, 2023 at 11:15:35AM +0300, Avihai Horon wrote:
> Hi all,
> 
> The first patch in this series adds a small optimization to VFIO
> migration by moving the STOP_COPY->STOP transition to
> vfio_save_cleanup(). Testing with a ConnectX-7 VFIO device showed that
> this can reduce downtime by up to 6%.
> 
> The rest of the series adds P2P support for VFIO migration.
> 
> VFIO migration uAPI defines an optional intermediate P2P quiescent
> state. While in the P2P quiescent state, P2P DMA transactions cannot be
> initiated by the device, but the device can respond to incoming ones.
> Additionally, all outstanding P2P transactions are guaranteed to have
> been completed by the time the device enters this state.

For clarity it is "all outstanding DMA transactions are guarenteed to
have been completed" - the device has no idea if something is P2P or
not.

> The purpose of this state is to support migration of multiple devices
> that are doing P2P transactions between themselves.

s/are/might/

Jason


  parent reply	other threads:[~2023-07-18 15:51 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-16  8:15 [PATCH for-8.2 0/6] vfio/migration: Add P2P support for VFIO migration Avihai Horon
2023-07-16  8:15 ` [PATCH for-8.2 1/6] vfio/migration: Move from STOP_COPY to STOP in vfio_save_cleanup() Avihai Horon
2023-07-30 16:25   ` Cédric Le Goater
2023-07-31  6:32     ` Avihai Horon
2023-07-31  7:05       ` Cédric Le Goater
2023-07-16  8:15 ` [PATCH for-8.2 2/6] sysemu: Add pre VM state change callback Avihai Horon
2023-07-27 16:23   ` Cédric Le Goater
2023-07-30  6:31     ` Avihai Horon
2023-07-30 16:22       ` Cédric Le Goater
2023-07-16  8:15 ` [PATCH for-8.2 3/6] qdev: Add qdev_add_vm_change_state_handler_full() Avihai Horon
2023-07-16  8:15 ` [PATCH for-8.2 4/6] vfio/migration: Refactor PRE_COPY and RUNNING state checks Avihai Horon
2023-07-21 11:33   ` Cédric Le Goater
2023-07-16  8:15 ` [PATCH for-8.2 5/6] vfio/migration: Add P2P support for VFIO migration Avihai Horon
2023-07-21 11:48   ` Cédric Le Goater
2023-07-23 10:37     ` Avihai Horon
2023-07-16  8:15 ` [PATCH for-8.2 6/6] vfio/migration: Allow migration of multiple P2P supporting devices Avihai Horon
2023-07-21 12:09   ` Cédric Le Goater
2023-07-23 10:42     ` Avihai Horon
2023-07-18 15:46 ` Jason Gunthorpe [this message]
2023-07-30  6:50   ` [PATCH for-8.2 0/6] vfio/migration: Add P2P support for VFIO migration Avihai Horon

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