From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>,
kvm@vger.kernel.org, "Michael S . Tsirkin" <mst@redhat.com>,
Juan Quintela <quintela@redhat.com>,
qemu-devel@nongnu.org, qemu-s390x@nongnu.org,
Paolo Bonzini <pbonzini@redhat.com>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH v1 07/17] migration/rdma: Use ram_block_discard_set_broken()
Date: Fri, 15 May 2020 18:51:05 +0100 [thread overview]
Message-ID: <20200515175105.GL2954@work-vm> (raw)
In-Reply-To: <96a58e88-2629-f2ee-5884-38d11e571548@redhat.com>
* David Hildenbrand (david@redhat.com) wrote:
> On 15.05.20 14:45, Dr. David Alan Gilbert wrote:
> > * David Hildenbrand (david@redhat.com) wrote:
> >> RDMA will pin all guest memory (as documented in docs/rdma.txt). We want
> >> to mark RAM block discards to be broken - however, to keep it simple
> >> use ram_block_discard_is_required() instead of inhibiting.
> >
> > Should this be dependent on whether rdma->pin_all is set?
> > Even with !pin_all some will be pinned at any given time
> > (when it's registered with the rdma stack).
>
> Do you know how much memory this is? Is such memory only temporarily pinned?
With pin_all not set, only a subset of memory, I think multiple 1MB
chunks, are pinned at any one time.
> At least with special-cases of vfio, it's acceptable if some memory is
> temporarily pinned - we assume it's only the working set of the driver,
> which guests will not inflate as long as they don't want to shoot
> themselves in the foot.
>
> This here sounds like the guest does not know the pinned memory is
> special, right?
Right - for RDMA it's all of memory that's being transferred, and the
guest doesn't see when each part is transferred.
Dave
> --
> Thanks,
>
> David / dhildenb
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2020-05-15 17:52 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-06 9:49 [PATCH v1 00/17] virtio-mem: Paravirtualized memory hot(un)plug David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 01/17] exec: Introduce ram_block_discard_set_(unreliable|required)() David Hildenbrand
2020-05-15 9:54 ` Dr. David Alan Gilbert
2020-05-15 14:40 ` David Hildenbrand
2020-05-15 14:54 ` David Hildenbrand
2020-05-15 16:15 ` Dr. David Alan Gilbert
2020-05-06 9:49 ` [PATCH v1 02/17] vfio: Convert to ram_block_discard_set_broken() David Hildenbrand
2020-05-15 12:01 ` David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 03/17] accel/kvm: " David Hildenbrand
2020-05-15 11:57 ` Dr. David Alan Gilbert
2020-05-06 9:49 ` [PATCH v1 04/17] s390x/pv: " David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 05/17] virtio-balloon: Rip out qemu_balloon_inhibit() David Hildenbrand
2020-05-15 12:09 ` Dr. David Alan Gilbert
2020-05-15 12:12 ` David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 06/17] target/i386: sev: Use ram_block_discard_set_broken() David Hildenbrand
2020-05-15 15:51 ` Dr. David Alan Gilbert
2020-05-06 9:49 ` [PATCH v1 07/17] migration/rdma: " David Hildenbrand
2020-05-15 12:45 ` Dr. David Alan Gilbert
2020-05-15 14:09 ` David Hildenbrand
2020-05-15 17:51 ` Dr. David Alan Gilbert [this message]
2020-05-15 17:59 ` David Hildenbrand
2020-05-15 18:36 ` Dr. David Alan Gilbert
2020-05-18 13:52 ` David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 08/17] migration/colo: " David Hildenbrand
2020-05-15 13:58 ` Dr. David Alan Gilbert
2020-05-15 14:05 ` David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 09/17] linux-headers: update to contain virtio-mem David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 10/17] virtio-mem: Paravirtualized memory hot(un)plug David Hildenbrand
2020-05-06 16:12 ` Eric Blake
2020-05-06 16:14 ` David Hildenbrand
2020-05-15 15:37 ` Dr. David Alan Gilbert
2020-05-15 16:48 ` David Hildenbrand
2020-05-18 14:23 ` David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 11/17] virtio-pci: Proxy for virtio-mem David Hildenbrand
2020-05-06 18:57 ` Pankaj Gupta
2020-05-18 13:34 ` David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 12/17] MAINTAINERS: Add myself as virtio-mem maintainer David Hildenbrand
2020-05-15 15:55 ` Dr. David Alan Gilbert
2020-05-06 9:49 ` [PATCH v1 13/17] hmp: Handle virtio-mem when printing memory device info David Hildenbrand
2020-05-06 19:03 ` Pankaj Gupta
2020-05-06 9:49 ` [PATCH v1 14/17] numa: Handle virtio-mem in NUMA stats David Hildenbrand
2020-05-06 9:49 ` [PATCH v1 15/17] pc: Support for virtio-mem-pci David Hildenbrand
2020-05-06 12:19 ` Pankaj Gupta
2020-05-06 9:49 ` [PATCH v1 16/17] virtio-mem: Allow notifiers for size changes David Hildenbrand
2020-05-15 16:46 ` Dr. David Alan Gilbert
2020-05-06 9:49 ` [PATCH v1 17/17] virtio-pci: Send qapi events when the virtio-mem " David Hildenbrand
2020-05-15 15:18 ` David Hildenbrand
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