From: Pawel Moll <pawel.moll@arm.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
"pagupta@redhat.com" <pagupta@redhat.com>,
Cornelia Huck <cornelia.huck@de.ibm.com>
Subject: Re: [PATCH RFC v5 net-next 4/6] virtio-net: add basic interrupt coalescing support
Date: Fri, 13 Feb 2015 12:41:06 +0000 [thread overview]
Message-ID: <1423831266.21394.1.camel@arm.com> (raw)
In-Reply-To: <874mqqbk12.fsf@rustcorp.com.au>
On Fri, 2015-02-13 at 02:52 +0000, Rusty Russell wrote:
> "Michael S. Tsirkin" <mst@redhat.com> writes:
> > On Tue, Feb 10, 2015 at 12:02:37PM +1030, Rusty Russell wrote:
> >> Jason Wang <jasowang@redhat.com> writes:
> >> > This patch enables the interrupt coalescing setting through ethtool.
> >>
> >> The problem is that there's nothing network specific about interrupt
> >> coalescing. I can see other devices wanting exactly the same thing,
> >> which means we'd deprecate this in the next virtio standard.
> >>
> >> I think the right answer is to extend like we did with
> >> vring_used_event(), eg:
> >>
> >> 1) Add a new feature VIRTIO_F_RING_COALESCE.
> >> 2) Add another a 32-bit field after vring_used_event(), eg:
> >> #define vring_used_delay(vr) (*(u32 *)((vr)->avail->ring[(vr)->num + 2]))
> >>
> >> This loses the ability to coalesce by number of frames, but we can still
> >> do number of sg entries, as we do now with used_event, and we could
> >> change virtqueue_enable_cb_delayed() to take a precise number if we
> >> wanted.
> >
> > But do we expect delay to be update dynamically?
> > If not, why not stick it in config space?
>
> Hmm, we could update it dynamically (and will, in the case of ethtool).
> But it won't be common, so we could append a field to
> virtio_pci_common_cfg for PCI.
>
> I think MMIO and CCW would be easy to extend too, but CC'd to check.
As far as I understand the virtio_pci_common_cfg principle (just had a
look, for the first time ;-), it's now an equivalent of the MMIO control
registers block. I see no major problem with adding another one.
Or were you thinking about introducing some standard for the "real"
config space? (fine with me as well - the transport will have nothing to
do :-)
Paweł
next prev parent reply other threads:[~2015-02-13 12:41 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-09 8:39 [PATCH RFC v5 net-next 0/6] enable tx interrupts for virtio-net Jason Wang
2015-02-09 8:39 ` [PATCH RFC v5 net-next 1/6] virtio_ring: fix virtqueue_enable_cb() when only 1 buffers were pending Jason Wang
2015-02-10 1:03 ` Rusty Russell
2015-02-10 6:26 ` Jason Wang
2015-02-10 10:18 ` Michael S. Tsirkin
2015-02-10 23:58 ` Rusty Russell
2015-02-11 5:41 ` Jason Wang
2015-02-09 8:39 ` [PATCH RFC v5 net-next 2/6] virtio_ring: try to disable event index callbacks in virtqueue_disable_cb() Jason Wang
2015-02-10 1:07 ` Rusty Russell
2015-02-10 10:24 ` Michael S. Tsirkin
2015-02-11 5:55 ` Jason Wang
2015-02-09 8:39 ` [PATCH RFC v5 net-next 3/6] virtio_net: enable tx interrupt Jason Wang
2015-02-09 8:39 ` [PATCH RFC v5 net-next 4/6] virtio-net: add basic interrupt coalescing support Jason Wang
2015-02-10 1:32 ` Rusty Russell
2015-02-10 6:51 ` Jason Wang
2015-02-10 10:25 ` Michael S. Tsirkin
2015-02-10 10:40 ` Michael S. Tsirkin
2015-02-13 2:52 ` Rusty Russell
2015-02-13 12:41 ` Pawel Moll [this message]
2015-02-16 3:07 ` Rusty Russell
2015-02-13 18:19 ` Cornelia Huck
2015-02-16 3:19 ` Rusty Russell
2015-02-09 8:39 ` [PATCH RFC v5 net-next 5/6] vhost: let vhost_signal() returns whether signalled Jason Wang
2015-02-09 8:39 ` [PATCH RFC v5 net-next 6/6] vhost_net: interrupt coalescing support Jason Wang
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