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Re: [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user
From: |
Felipe Franciosi |
Subject: |
Re: [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user |
Date: |
Tue, 18 Oct 2016 16:21:57 +0000 |
> On 18 Oct 2016, at 16:25, Marc-André Lureau <address@hidden> wrote:
>
> Hi Felipe
>
> ----- Original Message -----
>> Hello,
>>
>>> On 18 Oct 2016, at 10:24, Marc-André Lureau <address@hidden>
>>> wrote:
>>>
>>> <...>
>>>
>>> diff --git a/contrib/libvhost-user/libvhost-user.h
>>> b/contrib/libvhost-user/libvhost-user.h
>>>
>>> <...>
>>>
>>> +#define VHOST_MAX_NR_VIRTQUEUE 8
>>> +#define VIRTQUEUE_MAX_SIZE 1024
>>
>> I think that the maximum number of VQs should be 1024 to match Qemu's.
>>
>> http://git.qemu.org/?p=qemu.git;a=blob;f=include/hw/virtio/virtio.h;h=b913aac45589449bcc5d8161651332f4b0d69c7f;hb=HEAD#l55
>
> That would make the VuDev structure quite big. We may want to set the nr of
> max queues in vu_init() instead, and allocate it there. I think this is
> rather a current limitation, but does not prevent iterating from there.
Well, it depends what we call "quite big". The only thing that depends on that
is:
> struct VuDev {
> <...>
> VuVirtq vq[VHOST_MAX_NR_VIRTQUEUE];
> <...>
And VuVirtq is 96 bytes in size (x86_64). So we're really talking about 768
bytes vs 96 KiB.
Actually, you can bring it down to 88 bytes by...
> typedef struct VuRing {
> unsigned int num;
> struct vring_desc *desc;
> struct vring_avail *avail;
> struct vring_used *used;
> uint64_t log_guest_addr;
> uint32_t flags;
... moving "flags" just below "num". Allows gcc to compact the struct better.
> } VuRing;
I'd rather fix this kind of thing sooner than later, but it's ultimately up to
you.
Felipe
- [Qemu-devel] [PATCH v2 0/6] Start a contrib/libvhost-user, Marc-André Lureau, 2016/10/18
- [Qemu-devel] [PATCH v2 0/6] Start a contrib/libvhost-user, Marc-André Lureau, 2016/10/18
- [Qemu-devel] [PATCH v2 1/6] tests/vhost-user-bridge: remove false comment, Marc-André Lureau, 2016/10/18
- [Qemu-devel] [PATCH v2 2/6] tests/vhost-user-bridge: remove unnecessary dispatcher_remove, Marc-André Lureau, 2016/10/18
- [Qemu-devel] [PATCH v2 3/6] tests/vhost-user-bridge: indicate peer disconnected, Marc-André Lureau, 2016/10/18
- [Qemu-devel] [PATCH v2 4/6] tests/vhost-user-bridge: do not accept more than one connection, Marc-André Lureau, 2016/10/18
- [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user, Marc-André Lureau, 2016/10/18
- Re: [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user, Felipe Franciosi, 2016/10/18
- Re: [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user, Felipe Franciosi, 2016/10/18
- Re: [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user, Marc-André Lureau, 2016/10/18
- Re: [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user,
Felipe Franciosi <=
- Re: [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user, Michael S. Tsirkin, 2016/10/27
- Re: [Qemu-devel] [PATCH v2 5/6] contrib: add libvhost-user, Felipe Franciosi, 2016/10/27
[Qemu-devel] [PATCH v2 6/6] tests/vhost-user-bridge: use contrib/libvhost-user, Marc-André Lureau, 2016/10/18