On Thu, Aug 15, 2013 at 7:59 PM, Richard W.M. Jones <rjo...@redhat.com> wrote: > On Thu, Aug 15, 2013 at 07:37:06PM +0200, richard -rw- weinberger wrote: >> On Wed, Aug 14, 2013 at 7:59 PM, Richard W.M. Jones <rjo...@redhat.com> >> wrote: >> > >> > I performed some benchmarks against KVM: >> > >> > http://rwmj.wordpress.com/2013/08/14/performance-of-user-mode-linux-as-a-libguestfs-backend/#content >> > >> > Notes for those that don't want to read all that, there are at least >> > two bugs I found: >> > >> > (1) fsync /dev/ubda (in the guest) is not honoured by the user-mode >> > linux process. It should do an fsync on the corresponding backing file. >> >> What exactly does libguestfs do? > > http://libguestfs.org/ ...
Meant regarding fsync()... >> > (2) The ssl<N>=... serial port is really slow, at least 10 times >> > slower than virtio-serial which is the equivalent KVM feature. >> > libguestfs is chatty over the serial port, and so this has a >> > significant knock-on impact all over the place. >> >> So, libguestfs transfers all data over a serial line?! > > Well, it requires an 8-bit clean, reliable, bi-directional connection > into the guest. We used to use TCP/IP but it's pretty slow compared > to virtio-serial and has a bunch of other problems. > > For the UML backend I used the serial port. There's no problem with > it -- it works and it's reliable, it's just slow. > >> We could hack a faster transport into UML. >> As UML is only a process we can very easily access >> the host. >> Have looked at hostfs? > > Not sure how hostfs would help? hostfs show how you can directly access the host... -- Thanks, //richard ------------------------------------------------------------------------------ Get 100% visibility into Java/.NET code with AppDynamics Lite! It's a free troubleshooting tool designed for production. Get down to code-level detail for bottlenecks, with <2% overhead. Download for free and get started troubleshooting in minutes. http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
