On 2015/4/24 15:27, Luke Gorrie wrote: > On 24 April 2015 at 03:01, Linhaifeng <haifeng.lin at huawei.com> wrote: > >> If not add memory fence what would happen? Packets loss or interrupt >> loss?How to test it ? >> > > You should be able to test it like this: > > 1. Boot two Linux kernel (e.g. 3.13) guests. > 2. Connect them via vhost switch. > 3. Run continuous traffic between them (e.g. iperf). > > I would expect that within a reasonable timeframe (< 1 hour) one of the > guests' network interfaces will hang indefinitely due to a missed interrupt. > > You won't be able to reproduce this using DPDK guests because they are not > using the same interrupt suppression method. > > This is a serious real-world problem. I wouldn't deploy the vhost > implementation without this fix. > > Cheers, > -Luke >
I think this patch can't resole this problem. On the other hand we still would miss interrupt. After add rte_mb() function the we want the case is : 1.write used->idx. ring is full or empty. 2.virtio_net open interrupt. 3.read avail->flags. but this case(miss interrupt) would happen too: 1.write used->idx. ring is full or empty. 2.read avail->flags. 3.virtio_net open interrupt.
