[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of use
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors |
Date: |
Tue, 18 Oct 2011 13:58:13 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Oct 17, 2011 at 09:28:12PM +0200, Jan Kiszka wrote:
> On 2011-10-17 17:48, Michael S. Tsirkin wrote:
> > On Mon, Oct 17, 2011 at 11:28:02AM +0200, Jan Kiszka wrote:
> >> This optimization was only required to keep KVM route usage low. Now
> >> that we solve that problem via lazy updates, we can drop the field. We
> >> still need interfaces to clear pending vectors, though (and we have to
> >> make use of them more broadly - but that's unrelated to this patch).
> >>
> >> Signed-off-by: Jan Kiszka <address@hidden>
> >
> > Lazy updates should be an implementation detail.
> > IMO resource tracking of vectors makes sense
> > as an API. Making devices deal with pending
> > vectors as a concept, IMO, does not.
>
> There is really no use for tracking the vector lifecycle once we have
> lazy updates (except for static routes). It's a way too invasive
> concept, and it's not needed for anything but KVM.
I think it's needed. The PCI spec states that when the device
does not need an interrupt anymore, it should clear the pending
bit. The use/unuse is IMO a decent API for this,
because it uses a familiar resource tracking concept.
Exposing this knowledge of msix to devices seems
like a worse API.
>
> If you want an example, check
> http://permalink.gmane.org/gmane.comp.emulators.kvm.devel/70915 and
> compare it to the changes done to hpet in this series.
>
> Jan
>
This seems to be a general argument that lazy updates are good?
I have no real problem with them, besides the fact that
we need an API to reserve space in the routing
table so that device setup can fail upfront.
--
MST
- [Qemu-devel] [RFC][PATCH 27/45] qemu-kvm: Lazily update MSI caches, (continued)
- [Qemu-devel] [RFC][PATCH 27/45] qemu-kvm: Lazily update MSI caches, Jan Kiszka, 2011/10/17
- [Qemu-devel] [RFC][PATCH 35/45] pci-assign: Polish assigned_dev_update_msix_mmio, Jan Kiszka, 2011/10/17
- [Qemu-devel] [RFC][PATCH 40/45] qemu-kvm: msix: Drop check for preexisting cap from msix_add_config, Jan Kiszka, 2011/10/17
- [Qemu-devel] [RFC][PATCH 18/45] qemu-kvm: Hook into MSI delivery at APIC level, Jan Kiszka, 2011/10/17
- [Qemu-devel] [RFC][PATCH 32/45] pci-assign: Factor out deassign_irq, Jan Kiszka, 2011/10/17
- [Qemu-devel] [RFC][PATCH 37/45] qemu-kvm: Clean up irqrouting API, Jan Kiszka, 2011/10/17
- [Qemu-devel] [RFC][PATCH 39/45] pci-assign: Use generic MSI support, Jan Kiszka, 2011/10/17
- [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Jan Kiszka, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Michael S. Tsirkin, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Jan Kiszka, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Jan Kiszka, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Michael S. Tsirkin, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Jan Kiszka, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Michael S. Tsirkin, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Jan Kiszka, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Michael S. Tsirkin, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Jan Kiszka, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Michael S. Tsirkin, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Jan Kiszka, 2011/10/18
- Re: [Qemu-devel] [RFC][PATCH 28/45] qemu-kvm: msix: Drop tracking of used vectors, Michael S. Tsirkin, 2011/10/18