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From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Yishai Hadas <yishaih@nvidia.com>,
	saeedm@nvidia.com, kvm@vger.kernel.org, netdev@vger.kernel.org,
	kuba@kernel.org, kevin.tian@intel.com, joao.m.martins@oracle.com,
	leonro@nvidia.com, maorg@nvidia.com, cohuck@redhat.com
Subject: Re: [PATCH V2 vfio 06/11] vfio: Introduce the DMA logging feature support
Date: Tue, 19 Jul 2022 17:08:25 -0300	[thread overview]
Message-ID: <20220719200825.GK4609@nvidia.com> (raw)
In-Reply-To: <20220719132514.7d21dfaf.alex.williamson@redhat.com>

On Tue, Jul 19, 2022 at 01:25:14PM -0600, Alex Williamson wrote:

> > We don't really expect user space to hit this limit, the RAM in QEMU is 
> > divided today to around ~12 ranges as we saw so far in our evaluation.
> 
> There can be far more for vIOMMU use cases or non-QEMU drivers.

Not really, it isn't dynamic so vIOMMU has to decide what it wants to
track up front. It would never make sense to track based on what is
currently mapped. So it will be some small list, probably a big linear
chunk of the IOVA space.

No idea why non-qemu cases would need to be so different?

> We're looking at a very narrow use case with implicit assumptions about
> the behavior of the user driver.  Some of those assumptions need to be
> exposed via the uAPI so that userspace can make reasonable choices.

I think we need to see a clear use case for more than a few 10's of
ranges before we complicate things. I don't see one. If one does crop
up someday it is easy to add a new query, or some other behavior.

Remember, the devices can't handle huge numbers of ranges anyhow, so
any userspace should not be designed to have more than a few tens in
the first place.

Jason

  reply	other threads:[~2022-07-19 20:08 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-14  8:12 [PATCH V2 vfio 00/11] Add device DMA logging support for mlx5 driver Yishai Hadas
2022-07-14  8:12 ` [PATCH V2 vfio 01/11] net/mlx5: Introduce ifc bits for page tracker Yishai Hadas
2022-07-21  8:28   ` Tian, Kevin
2022-07-21  8:43     ` Yishai Hadas
2022-07-14  8:12 ` [PATCH V2 vfio 02/11] net/mlx5: Query ADV_VIRTUALIZATION capabilities Yishai Hadas
2022-07-14  8:12 ` [PATCH V2 vfio 03/11] vfio: Introduce DMA logging uAPIs Yishai Hadas
2022-07-18 22:29   ` Alex Williamson
2022-07-19  1:39     ` Tian, Kevin
2022-07-19  5:40       ` Kirti Wankhede
2022-07-19  7:49     ` Yishai Hadas
2022-07-19 19:57       ` Alex Williamson
2022-07-19 20:18         ` Jason Gunthorpe
2022-07-21  8:45   ` Tian, Kevin
2022-07-21 12:05     ` Jason Gunthorpe
2022-07-25  7:20       ` Tian, Kevin
2022-07-25 14:33         ` Jason Gunthorpe
2022-07-26  7:07           ` Tian, Kevin
     [not found]     ` <56bd06d3-944c-18da-86ed-ae14ce5940b7@nvidia.com>
2022-07-25  7:30       ` Tian, Kevin
2022-07-26  8:37         ` Yishai Hadas
2022-07-26 14:03           ` Alex Williamson
2022-07-26 15:04             ` Jason Gunthorpe
2022-07-28  4:05               ` Tian, Kevin
2022-07-28 12:06                 ` Jason Gunthorpe
2022-07-29  3:01                   ` Tian, Kevin
2022-07-29 14:11                     ` Jason Gunthorpe
2022-07-14  8:12 ` [PATCH V2 vfio 04/11] vfio: Move vfio.c to vfio_main.c Yishai Hadas
2022-07-14  8:12 ` [PATCH V2 vfio 05/11] vfio: Add an IOVA bitmap support Yishai Hadas
2022-07-18 22:30   ` Alex Williamson
2022-07-18 22:46     ` Jason Gunthorpe
2022-07-19 19:01   ` Alex Williamson
2022-07-20  1:57     ` Joao Martins
2022-07-20 16:47       ` Alex Williamson
2022-07-20 17:27         ` Jason Gunthorpe
2022-07-20 18:16         ` Joao Martins
2022-07-14  8:12 ` [PATCH V2 vfio 06/11] vfio: Introduce the DMA logging feature support Yishai Hadas
2022-07-18 22:30   ` Alex Williamson
2022-07-19  9:19     ` Yishai Hadas
2022-07-19 19:25       ` Alex Williamson
2022-07-19 20:08         ` Jason Gunthorpe [this message]
2022-07-21  8:54           ` Tian, Kevin
2022-07-21 11:50             ` Jason Gunthorpe
2022-07-25  7:38               ` Tian, Kevin
2022-07-25 14:37                 ` Jason Gunthorpe
2022-07-26  7:34                   ` Tian, Kevin
2022-07-26 15:12                     ` Jason Gunthorpe
2022-07-14  8:12 ` [PATCH V2 vfio 07/11] vfio/mlx5: Init QP based resources for dirty tracking Yishai Hadas
2022-07-14  8:12 ` [PATCH V2 vfio 08/11] vfio/mlx5: Create and destroy page tracker object Yishai Hadas
2022-07-14  8:12 ` [PATCH V2 vfio 09/11] vfio/mlx5: Report dirty pages from tracker Yishai Hadas
2022-07-14  8:12 ` [PATCH V2 vfio 10/11] vfio/mlx5: Manage error scenarios on tracker Yishai Hadas
2022-07-14  8:12 ` [PATCH V2 vfio 11/11] vfio/mlx5: Set the driver DMA logging callbacks Yishai Hadas
2022-07-21  8:26 ` [PATCH V2 vfio 00/11] Add device DMA logging support for mlx5 driver Tian, Kevin
2022-07-21  8:55   ` Yishai Hadas

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