Hi > -----Original Message----- > From: Yuanhan Liu [mailto:y...@fridaylinux.org] > Sent: Monday, January 8, 2018 10:07 PM > To: Chen, Junjie J <junjie.j.c...@intel.com> > Cc: Wang, Xiao W <xiao.w.w...@intel.com>; maxime.coque...@redhat.com; > Bie, Tiwei <tiwei....@intel.com>; dev@dpdk.org; Yao, Lei A > <lei.a....@intel.com> > Subject: Re: [PATCH v6] vhost: support virtqueue interrupt/notification > suppression > > 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.c...@intel.com> > > You need put "---" before the change log. Otherwise, it will be tracked in the > commit log.
Will update this. > > > +#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. The vring_used_event is defined and used for virtio in kernel, kernel defines a vhost_used_event in vhost.c for vhost, so I just use a separated macro for vhost end. I'd like to define both vhost_need_event and vhost_used_event in vhost.h to remove potential build issue in old linux distribution and also to keep consistent. Is that OK for you? > > 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. Sure. > > - 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. Sure, will do this. > > --yliu