[Spice-devel] [RFC spice-gtk 0/5] Quality of Service and monitoring network usage

[Victor Toso]

From: Victor Toso <me at victortoso.com>

Hi,

For a while now I've been playing with the overall network usage with
spice-gtk and trying to think in a way to avoid situations where
channels which are transferring files don't interfere too much on
channels like display or input as they are very important to the user
experience.

This has been proved quite difficult (tm) but hopefully this patches can
help.

In the last patch, I'm measuring and storing the data rate for read and
write on each channel in order to plot charts for seeing what is going
on in regard network usage per channel.

I'm considering moving this 'saving network data' to spice-gtk so we can
make it more usable with other clients too. Opinions?

I've saved 5 tests + images at [0] and I'll mention them in the notes
bellow. All the tests were using Fedora 25 (client and guest) and I'm
targeting only webdav + display channels.

[0] https://people.freedesktop.org/~victortoso/imgs/spice/qos-tests/

In the first 03 tests I'm transferring two files (second only when the
first one is done) 200MB and 400MB in size, from the guest fs to the
shared folder. During the whole time the stopwatch from Clocks app is
running as it does a great job drawing several times per second :)

Streaming and image compression are off.

In tests 04-05 I'm transferring a bigger file (1.4 GB) with caution as
it is *very easy* to run out of memory in the host and having the VM
killed by the operation system. Bug [1] is around spice-server not
controlling the amount of data it is storing.

[1] https://bugs.freedesktop.org/show_bug.cgi?id=100550

So, a few notes of this experience:

* I'm quite amazed by how much data the display-channel can transfer.
  Considering client-machine = host-machine, data rate can go as big as
  ~200 MiB/s but my feeling is that having overall bandwidth of 50 MiB/s
  did not affect _my_ user experience in those tests.

* I can see the throttling working but I wonder if it should be
  more/less aggressive depending on the network usage?

* A few bugs around memory usage. By default, if we have to store a file
  in memory we should be more careful about it.

Last but not least, I wonder if we should have an option to limit
bandwidth usage for the whole session. I think it can be easy to extend
this patches to achieve that.

Thanks for any comments,
    toso

PS: code in qos branch of
https://gitlab.com/victortoso/spice-gtk/

Victor Toso (5):
  spice-channel: new 'total-write-bytes' property
  qos: introduce quality of service to channels
  qos: bandwidth computation
  qos: introduce channel priority throttling
  spicy: save data measurements for each channel

 src/spice-channel-priv.h |   1 +
 src/spice-channel.c      |  51 ++++++
 src/spice-option.c       |   5 +
 src/spice-session-priv.h |   5 +
 src/spice-session.c      | 469 ++++++++++++++++++++++++++++++++++++++++++++++-
 tools/spicy-gnuplot.sh   |  19 ++
 tools/spicy.c            | 259 +++++++++++++++++++++++++-
 7 files changed, 807 insertions(+), 2 deletions(-)
 create mode 100755 tools/spicy-gnuplot.sh

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