Hi ----- Original Message ----- > On Wed, Mar 23, 2016 at 03:34:09PM +0000, shesha Sreenivasamurthy (shesha) > wrote: > > Hi All, > > > > I was going over vhost-user migration capability in DPDK in lieu of a > > Cisco's > > multi-q DPDK vhost-user application. I see that log_base address is > > implemented > > as per virtio_net device. However, desc, addr and used is per > > vhost_virtqueue. > > Additionally, QEMU sends one VHOST_USER_SET_LOG_BASE per queue-pair (QEMU - > > hw/ > > virtio/vhost.c::vhost_dev_set_log). > > > > Does it mean we need to log dirty pages of all rings to same location ? > > Hi, > > Yes, and QEMU allocates only one block of memory (see vhost_log_alloc()) > after all.
> > If that > > is the case then why does QEMU sends separate VHOST_USER_SET_LOG_BASE per > > queue > > pair ? > > That's kind of like a design. One queue pair is associated with one > vhost_dev struct in QEMU, hence, all those requests will go through > vhost_dev structs (aka, all qeueu pairs), including those that one > time request is needed only, such as VHOST_USER_SET_MEM_TABLE. Thus, > we introduced vhost_user_one_time_request() to avoid such case. I am not familiar with multi-queue, but I can see that in vhost_net_start. > So, good question, and we may need add it to the "one time request" > group, Marc? That would probably prevent vhost_dev_log_resize(), so it would need some kind of "force" flag. I am not sure it's worth it at this point. > > And FYI, for queue-pair (or vring) request, there should be an index > in the payload, to point to the right vring. If not, it normally > means a global request, that _may_ need be sent once only. > > --yliu >
