Re: [Qemu-devel] [PATCH 0/2] Dynamic module support for block drivers

[Stefan Hajnoczi <stefanha@gmail.com>]

On Thu, Sep 03, 2015 at 08:07:40PM +0200, Marc Marí wrote:
> On Thu, 3 Sep 2015 17:12:29 +0100
> Stefan Hajnoczi <stefanha@gmail.com> wrote:
> 
> > On Mon, Aug 17, 2015 at 10:09:33AM +0200, Marc Marí wrote:
> > > The current module infrastructure has been improved to enable
> > > dynamic module loading.
> > > 
> > > This reduces the load time for very simple guests. For the following
> > > configuration (very loaded)
> > > 
> > > ./configure --enable-sdl --enable-gtk --enable-vte --enable-curses \
> > >     --enable-vnc --enable-vnc-{jpeg,tls,sasl,png} --enable-virtfs \
> > >     --enable-brlapi --enable-curl --enable-fdt --enable-bluez \
> > >     --enable-kvm --enable-rdma --enable-uuid --enable-vde \
> > >     --enable-linux-aio --enable-cap-ng --enable-attr
> > > --enable-vhost-net \ --enable-vhost-scsi --enable-spice
> > > --enable-rbd --enable-libiscsi \ --enable-smartcard-nss
> > > --enable-guest-agent --enable-libusb \ --enable-usb-redir
> > > --enable-lzo --enable-snappy --enable-bzip2 \ --enable-seccomp
> > > --enable-coroutine-pool --enable-glusterfs \ --enable-tpm
> > > --enable-libssh2 --enable-vhdx --enable-numa \ --enable-tcmalloc
> > > --target-list=x86_64-softmmu
> > > 
> > > With modules disabled, there are 142 libraries loaded at startup.
> > > Time is the following:
> > >  LD time: 0.065 seconds
> > >  QEMU time: 0.02 seconds
> > >  Total time: 0.085 seconds
> > > 
> > > With this patch series and modules enabled, there are 128 libraries
> > > loaded at startup. Time is the following:
> > >  LD time: 0.02 seconds
> > >  QEMU time: 0.02 seconds
> > >  Total time: 0.04 seconds
> > > 
> > > Where LD time is the time between the program startup and the jump
> > > to main, and QEMU time is the time between the start of main and
> > > the first kvm_entry.
> > > 
> > > These results are just with a few block drivers, that were already
> > > a module. Adding more modules (block or not block) should be easy,
> > > and will reduce the load time even more.
> > 
> > Which QEMU command-line did you benchmark?
> > 
> > Did you have a UI enabled (SDL/GTK/VNC)?
> 
> x86_64-softmmu/qemu-system-x86_64 --enable-kvm \
>     -kernel /boot/vmlinuz-4.1.4-200.fc22.x86_64 -nographic

Nice, these times are very good.

Stefan