From: John Levon <levon@movementarian.org>
To: "Cédric Le Goater" <clg@redhat.com>
Cc: qemu-devel@nongnu.org, "Jason Herne" <jjherne@linux.ibm.com>,
"Thanos Makatos" <thanos.makatos@nutanix.com>,
"Halil Pasic" <pasic@linux.ibm.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
"Eric Farman" <farman@linux.ibm.com>,
"Tony Krowiak" <akrowiak@linux.ibm.com>,
"Thomas Huth" <thuth@redhat.com>,
qemu-s390x@nongnu.org, "Matthew Rosato" <mjrosato@linux.ibm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Marc-André Lureau" <marcandre.lureau@redhat.com>,
"Stefano Garzarella" <sgarzare@redhat.com>,
"Alex Williamson" <alex.williamson@redhat.com>,
"David Hildenbrand" <david@redhat.com>,
"Peter Xu" <peterx@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Jagannathan Raman" <jag.raman@oracle.com>,
"John Johnson" <john.g.johnson@oracle.com>,
"Elena Ufimtseva" <elena.ufimtseva@oracle.com>
Subject: Re: [PATCH v8 08/28] vfio: add region cache
Date: Fri, 4 Apr 2025 18:18:20 +0100 [thread overview]
Message-ID: <Z/AUXIyeZjUWwdPu@movementarian.org> (raw)
In-Reply-To: <33a54cce-c9a3-4724-97ef-64ac6a96e5b7@redhat.com>
On Fri, Apr 04, 2025 at 06:57:46PM +0200, Cédric Le Goater wrote:
> > > why not populate vbasedev->regions[index] in vfio_get_all_regions() ?
> >
> > Good question. I presume it's not possible for us to ever look up a region
> > that has somehow appeared *after* vfio_prepare_device() ?
> >
> > We'd end up off the end of the array in that case anyway.
>
> I was confused. I thought we were caching VFIORegions ...
>
> Anyway, this is an optimisation and I fail to understand where
> the VFIO_DEVICE_GET_REGION_INFO ioctl is called on a hot path.
>
> Is it for interrupts ? Please explain.
>
> Do you have figures ?
That's a great question that I don't know the answer to (like much of this code
I just inherited it). Let me try to investigate.
regards
john
next prev parent reply other threads:[~2025-04-04 17:19 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-19 14:48 [PATCH v8 00/28] vfio-user client John Levon
2025-02-19 14:48 ` [PATCH v8 01/28] vfio/container: pass MemoryRegion to DMA operations John Levon
2025-04-02 16:44 ` Cédric Le Goater
2025-02-19 14:48 ` [PATCH v8 02/28] vfio/container: pass listener_begin/commit callbacks John Levon
2025-04-02 12:30 ` Cédric Le Goater
2025-02-19 14:48 ` [PATCH v8 03/28] vfio/container: support VFIO_DMA_UNMAP_FLAG_ALL John Levon
2025-04-02 16:49 ` Cédric Le Goater
2025-04-03 9:45 ` John Levon
2025-04-04 15:43 ` Cédric Le Goater
2025-02-19 14:48 ` [PATCH v8 04/28] vfio: add vfio_attach_device_by_iommu_type() John Levon
2025-04-02 16:52 ` Cédric Le Goater
2025-02-19 14:48 ` [PATCH v8 05/28] vfio: add vfio_prepare_device() John Levon
2025-04-03 9:19 ` Cédric Le Goater
2025-04-03 9:34 ` John Levon
2025-04-04 15:41 ` Cédric Le Goater
2025-04-04 15:45 ` John Levon
2025-02-19 14:48 ` [PATCH v8 06/28] vfio: refactor out vfio_interrupt_setup() John Levon
2025-04-03 9:23 ` Cédric Le Goater
2025-04-03 9:38 ` John Levon
2025-02-19 14:48 ` [PATCH v8 07/28] vfio: refactor out vfio_pci_config_setup() John Levon
2025-04-03 9:30 ` Cédric Le Goater
2025-02-19 14:48 ` [PATCH v8 08/28] vfio: add region cache John Levon
2025-04-03 15:46 ` Cédric Le Goater
2025-04-03 16:00 ` John Levon
2025-04-04 16:57 ` Cédric Le Goater
2025-04-04 17:18 ` John Levon [this message]
2025-04-08 13:48 ` John Levon
2025-02-19 14:48 ` [PATCH v8 09/28] vfio: split out VFIOKernelPCIDevice John Levon
2025-04-03 17:13 ` Cédric Le Goater
2025-04-03 18:08 ` John Levon
2025-04-04 12:49 ` Cédric Le Goater
2025-04-04 14:21 ` John Levon
2025-04-04 14:48 ` Cédric Le Goater
2025-04-04 15:44 ` John Levon
2025-02-19 14:48 ` [PATCH v8 10/28] vfio: add device IO ops vector John Levon
2025-04-04 14:36 ` Cédric Le Goater
2025-04-04 15:53 ` John Levon
2025-02-19 14:48 ` [PATCH v8 11/28] vfio-user: introduce vfio-user protocol specification John Levon
2025-02-19 14:48 ` [PATCH v8 12/28] vfio-user: add vfio-user class and container John Levon
2025-02-19 14:48 ` [PATCH v8 13/28] vfio-user: connect vfio proxy to remote server John Levon
2025-02-19 14:48 ` [PATCH v8 14/28] vfio-user: implement message receive infrastructure John Levon
2025-02-19 14:48 ` [PATCH v8 15/28] vfio-user: implement message send infrastructure John Levon
2025-02-19 14:48 ` [PATCH v8 16/28] vfio-user: implement VFIO_USER_DEVICE_GET_INFO John Levon
2025-02-19 14:48 ` [PATCH v8 17/28] vfio-user: implement VFIO_USER_DEVICE_GET_REGION_INFO John Levon
2025-02-19 14:48 ` [PATCH v8 18/28] vfio-user: implement VFIO_USER_REGION_READ/WRITE John Levon
2025-02-19 14:48 ` [PATCH v8 19/28] vfio-user: set up PCI in vfio_user_pci_realize() John Levon
2025-02-19 14:48 ` [PATCH v8 20/28] vfio-user: implement VFIO_USER_DEVICE_GET/SET_IRQ* John Levon
2025-02-19 14:48 ` [PATCH v8 21/28] vfio-user: forward MSI-X PBA BAR accesses to server John Levon
2025-02-19 14:48 ` [PATCH v8 22/28] vfio-user: set up container access to the proxy John Levon
2025-02-19 14:48 ` [PATCH v8 23/28] vfio-user: implement VFIO_USER_DEVICE_RESET John Levon
2025-02-19 14:48 ` [PATCH v8 24/28] vfio-user: implement VFIO_USER_DMA_MAP/UNMAP John Levon
2025-02-19 14:48 ` [PATCH v8 25/28] vfio-user: implement VFIO_USER_DMA_READ/WRITE John Levon
2025-02-19 14:48 ` [PATCH v8 26/28] vfio-user: add 'no-direct-dma' option John Levon
2025-02-19 14:48 ` [PATCH v8 27/28] vfio-user: add 'x-msg-timeout' option John Levon
2025-02-19 14:48 ` [PATCH v8 28/28] vfio-user: add coalesced posted writes John Levon
2025-02-28 17:09 ` [PATCH v8 00/28] vfio-user client Jag Raman
2025-03-03 11:19 ` John Levon
2025-03-03 15:39 ` Jag Raman
2025-03-14 14:25 ` Cédric Le Goater
2025-03-14 14:48 ` Steven Sistare
2025-03-18 10:00 ` Cédric Le Goater
2025-03-14 15:13 ` John Levon
2025-03-18 10:02 ` Cédric Le Goater
2025-04-04 17:21 ` Cédric Le Goater
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