On Mon, Feb 03, 2020 at 04:17:31PM +0000, Daniel P. Berrangé wrote: > On Thu, Jan 30, 2020 at 06:06:20PM +0100, Ján Tomko wrote: > > Add a document describing the usage of virtiofs. > > --- > > docs/kbase.html.in | 3 + > > docs/kbase/virtiofs.rst | 152 ++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 155 insertions(+) > > create mode 100644 docs/kbase/virtiofs.rst > > > > diff --git a/docs/kbase.html.in b/docs/kbase.html.in > > index c156414c41..7d6caf3cb1 100644 > > --- a/docs/kbase.html.in > > +++ b/docs/kbase.html.in > > @@ -29,6 +29,9 @@ > > <dt><a href="kbase/backing_chains.html">Backing chain > > management</a></dt> > > <dd>Explanation of how disk backing chain specification impacts > > libvirt's > > behaviour and basic troubleshooting steps of disk problems.</dd> > > + > > + <dt><a href="kbase/virtiofs.html">Virtio-FS</a></dt> > > + <dd>Share a filesystem between the guest and the host</dd> > > </dl> > > </div> > > > > diff --git a/docs/kbase/virtiofs.rst b/docs/kbase/virtiofs.rst > > new file mode 100644 > > index 0000000000..e76ff8ca4b > > --- /dev/null > > +++ b/docs/kbase/virtiofs.rst > > @@ -0,0 +1,152 @@ > > +============================ > > +Sharing files with Virtio-FS > > +============================ > > + > > +=== 8< delete before merging 8< === > > +NOTE: if you're looking at this note, this is just a proposal. > > +See the up-to-date version on: https://libvirt.org/kbase/virtiofs.html > > +=== 8< --------------------- 8< === > > ...this shouldn't be here still > > > + > > +.. contents:: > > + > > +========= > > +Virtio-FS > > +========= > > + > > +Virtio-FS is a shared file system that lets virtual machines access > > +a directory tree on the host. Unlike existing approaches, it > > +is designed to offer local file system semantics and performance. > > + > > +See https://virtio-fs.gitlab.io/ > > + > > +========== > > +Host setup > > +========== > > + > > +The host-side virtiofsd daemon, like other vhost-user backed devices, > > +requres shared memory between the host and the guest. As of QEMU 4.2, this > > requires > > > +requires specifying a NUMA topology for the guest and explicitly specifying > > +a memory backend. Multiple options are available: > > + > > +Either of the following: > > + > > +\a) Use file-backed memory > > Why are you disabling list-ification here & throughout the file ? > > > + > > +Configure the directory where the files backing the memory will be stored > > +with the ``memory_backing_dir`` option in ``/etc/libvirt/qemu.conf`` > > + > > +:: > > + > > + # This directory is used for memoryBacking source if configured as file. > > + # NOTE: big files will be stored here > > + memory_backing_dir = "/dev/shm/" > > + > > +\b) Use hugepage-backed memory > > + > > +Make sure there are enough huge pages allocated for the requested guest > > memory. > > +For example, for one guest with 2 GiB of RAM backed by 2 MiB hugepages: > > + > > +:: > > + > > + # virsh allocpages 2M 1024 > > > I'm not understanding from this how big the files will be for > virtiofsd ? How much memory should users expect to be needed > per-guest per-virtiofsd ?
Oh, I realize on re-reading that this part of the docs is just about the general setup of a file backed guest. So we're just talking about guest RAM size here, virtiofsd isn't using this file backing for anything else. IOW, ignore this comment. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
