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Re: [Qemu-devel] [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache |
Date: |
Mon, 17 Oct 2011 13:31:40 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2011-10-17 13:25, Avi Kivity wrote:
> On 10/17/2011 01:19 PM, Jan Kiszka wrote:
>>> IMO this needlessly leaks kvm information into core qemu. The cache
>>> should be completely hidden in kvm code.
>>>
>>> I think msi_deliver() can hide the use of the cache completely. For
>>> pre-registered events like kvm's irqfd, you can use something like
>>>
>>> qemu_irq qemu_msi_irq(MSIMessage msg)
>>>
>>> for non-kvm, it simply returns a qemu_irq that triggers a stl_phys();
>>> for kvm, it allocates an irqfd and a permanent entry in the cache and
>>> returns a qemu_irq that triggers the irqfd.
>>
>> See my previously mail: you want to track the life-cycle of an MSI
>> source to avoid generating routes for identical sources. A messages is
>> not a source. Two identical messages can come from different sources. So
>> we need a separate data structure for that purpose.
>>
>
> Yes, I understand this now.
>
> Just to make sure I understand this completely: a hash table indexed by
> MSIMessage in kvm code would avoid this? You'd just allocate on demand
> when seeing a new MSIMessage and free on an LRU basis, avoiding pinned
> entries.
>
> I'm not advocating this (yet), just want to understand the tradeoffs.
Practically, that may work. I just wanted to avoid searching. And for
static routes (irqfd, device assigment) you still need caches anyway, so
I decided to use them consistently.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- Re: [Qemu-devel] [RFC][PATCH 08/45] Introduce MSIMessage structure, (continued)
- Re: [Qemu-devel] [RFC][PATCH 08/45] Introduce MSIMessage structure, Jan Kiszka, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 08/45] Introduce MSIMessage structure, Michael S. Tsirkin, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 08/45] Introduce MSIMessage structure, Jan Kiszka, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 08/45] Introduce MSIMessage structure, Michael S. Tsirkin, 2011/10/17
- Re: [Qemu-devel] [RFC][PATCH 08/45] Introduce MSIMessage structure, Jan Kiszka, 2011/10/18
[Qemu-devel] [RFC][PATCH 16/45] qemu-kvm: Use MSIMessage and MSIRoutingCache, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache, Jan Kiszka, 2011/10/17
Re: [Qemu-devel] [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache, Michael S. Tsirkin, 2011/10/17
Re: [Qemu-devel] [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache, Jan Kiszka, 2011/10/18
Re: [Qemu-devel] [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache, Michael S. Tsirkin, 2011/10/18
Re: [Qemu-devel] [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache, Jan Kiszka, 2011/10/18
Re: [Qemu-devel] [RFC][PATCH 12/45] msi: Introduce MSIRoutingCache, Michael S. Tsirkin, 2011/10/17
[Qemu-devel] [RFC][PATCH 03/45] msi: Use msi/msix_present more consistently, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 19/45] qemu-kvm: Factor out kvm_msi_irqfd_set, Jan Kiszka, 2011/10/17
[Qemu-devel] [RFC][PATCH 21/45] qemu-kvm: msix: Don't fire notifier spuriously on set/unset, Jan Kiszka, 2011/10/17