From: Yuanhan Liu <yliu@fridaylinux.org>
To: Junjie Chen <junjie.j.chen@intel.com>
Cc: xiao.w.wang@intel.com, maxime.coquelin@redhat.com,
tiwei.bie@intel.com, dev@dpdk.org, "Yao,
Lei A" <lei.a.yao@intel.com>
Subject: Re: [dpdk-dev] [PATCH v6] vhost: support virtqueue interrupt/notification suppression
Date: Mon, 8 Jan 2018 22:06:59 +0800 [thread overview]
Message-ID: <20180108140659.GA29540@yliu-mob> (raw)
In-Reply-To: <1514310190-140916-1-git-send-email-junjie.j.chen@intel.com>
On Tue, Dec 26, 2017 at 12:43:10PM -0500, Junjie Chen wrote:
> The driver can suppress interrupt when VIRTIO_F_EVENT_IDX feature bit is
> negotiated. The driver set vring flags to 0, and MAY use used_event in
> available ring to advise device interrupt util reach an index specified
> by used_event. The device ignore the lower bit of vring flags, and send
> an interrupt when index reach used_event.
>
> The device can suppress notification in a manner analogous to the ways
> driver suppress interrupt. The device manipulates flags or avail_event in
> the used ring in the same way the driver manipulates flags or used_event in
> available ring.
>
> This patch is to enable this feature in vhost.
>
> Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
You need put "---" before the change log. Otherwise, it will be tracked in
the commit log.
> +#define vhost_used_event(vr) \
> + (*(volatile uint16_t*)&(vr)->avail->ring[(vr)->size])
> +
> +static __rte_always_inline void
> +vhost_notify(struct virtio_net *dev, struct vhost_virtqueue *vq)
> +{
> + /* Don't notify guest if we don't reach index specified by guest. */
> + if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
> + uint16_t old = vq->signalled_used;
> + uint16_t new = vq->last_used_idx;
> +
> + LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d, new=%d\n",
> + __func__,
> + vhost_used_event(vq),
> + old, new);
> + if (vring_need_event(vhost_used_event(vq), new, old)
It's a bit weird that you use one from the standard linux header file
(vring_need_event), while you define you own one (vhost_used_event).
Note that the system header file also has "vring_used_event()" defined.
Besides that, I have few more comments (and some requirements):
- It'd be much better if there is a Tested-by tag. Expeclitly,
I'm asking a test with Linux kernel virtio-net driver in guest.
- I also hope you could have done a build test on some old distributions.
AFAIK, the two macros (vring_need_event and vring_used_event) come
from kernel 3.0 (or above). Any kernel older than that would fail
the build.
- I'd be great if you could make a new one based on top of my latest
tree: I have just applied a patchset that should conflict with this
one.
--yliu
next prev parent reply other threads:[~2018-01-08 14:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-28 11:02 [dpdk-dev] [PATCH v4] " junjie.j.chen
2017-12-23 16:55 ` [dpdk-dev] [PATCH v5] " Junjie Chen
2017-12-26 8:03 ` Wang, Xiao W
2017-12-26 17:43 ` [dpdk-dev] [PATCH v6] " Junjie Chen
2018-01-05 5:25 ` Wang, Xiao W
2018-01-08 14:06 ` Yuanhan Liu [this message]
2018-01-09 2:12 ` Chen, Junjie J
2018-01-09 2:29 ` Yuanhan Liu
2018-01-09 11:03 ` [dpdk-dev] [PATCH v7] " Junjie Chen
2018-01-09 7:34 ` Yao, Lei A
2018-01-09 12:58 ` Yuanhan Liu
2018-01-09 8:56 ` Maxime Coquelin
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