Hi,
Currently, the maximum number of supported memory regions for vhost-user
backends is 8,
and the maximum supported memory regions for vhost-net backends is determined
by
" /sys/module/vhost/parameters/max_mem_regions".
In many scenarios, the vhost-user NIC will cause the memory region to become a
bottleneck, reports
"a used vhost backend has no free memory slots left".
Such as memory hotplug (need to support multiple memory slots),
and GPU pass-through (need to register multiple bar regions) and so on.
So, my questions are: Why definition vhost-user memory card memory region up to
8?
Does it have any side effects if we increase the VHOST_MEMORY_MAX_NREGIONS?
What about cross-version migration?
#define VHOST_MEMORY_MAX_NREGIONS 8
static int vhost_user_memslots_limit(struct vhost_dev *dev)
{
return VHOST_MEMORY_MAX_NREGIONS;
}
Which is introduced by
commit 5f6f6664bf24dc53f4bf98ba812d55ca93684cd5
Author: Nikolay Nikolaev <n.nikol...@virtualopensystems.com>
Date: Tue May 27 15:06:02 2014 +0300
Add vhost-user as a vhost backend.
The initialization takes a chardev backed by a unix domain socket.
It should implement qemu_fe_set_msgfds in order to be able to pass
file descriptors to the remote process.
Each ioctl request of vhost-kernel has a vhost-user message equivalent,
which is sent over the control socket.
The general approach is to copy the data from the supplied argument
pointer to a designated field in the message. If a file descriptor is
to be passed it will be placed in the fds array for inclusion in
the sendmsg control header.
VHOST_SET_MEM_TABLE ignores the supplied vhost_memory structure and scans
the global ram_list for ram blocks with a valid fd field set. This would
be set when the '-object memory-file' option with share=on property is used.
Signed-off-by: Antonios Motakis <a.mota...@virtualopensystems.com>
Signed-off-by: Nikolay Nikolaev <n.nikol...@virtualopensystems.com>
Reviewed-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
Thanks,
-Gonglei
