> -----Original Message----- > From: Linhaifeng [mailto:haifeng.lin at huawei.com] > Sent: Monday, March 23, 2015 8:24 PM > To: dev at dpdk.org > Cc: Ouyang, Changchun; Xie, Huawei > Subject: Re: [dpdk-dev] [PATCH] cast used->idx to volatile > > > > On 2015/3/21 16:07, linhaifeng wrote: > > From: Linhaifeng <haifeng.lin at huawei.com> > > > > Same as rte_vhost_enqueue_burst we should cast used->idx > > to volatile before notify guest. > > > > Signed-off-by: Linhaifeng <haifeng.lin at huawei.com> > > --- > > lib/librte_vhost/vhost_rxtx.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c > > index 535c7a1..8d674d1 100644 > > --- a/lib/librte_vhost/vhost_rxtx.c > > +++ b/lib/librte_vhost/vhost_rxtx.c > > @@ -722,7 +722,7 @@ rte_vhost_dequeue_burst(struct virtio_net *dev, > uint16_t queue_id, > > } > > > > rte_compiler_barrier(); > > - vq->used->idx += entry_success; > > + *(volatile uint16_t *)&vq->used->idx += entry_success;
Haifeng: We have compiler barrier before and an external function call behind, so we don't need volatile here. Do you meet issue? > > /* Kick guest if required. */ > > if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)) > > eventfd_write((int)vq->callfd, 1); > > > > -- > Regards, > Haifeng
