Set is much slower to iterate through (due to cache misses and such) and
the only advantage of using set is faster removal of link. However, we are
iterating links much much more often than removing them, and even when we
are removing links we don't really need to remove link from nodes which it
connects -- we don't support partial depsgraph updates, so removing links
from nodes on destruction is a waste of time.
If we ever want to support partial updates we can have dedicated function
to remove link from nodes it connects.
This gives a surprising increase of fps from 42 to 56 with test file from
Mr. J.P.Bouza (blenrig_for_debugging.blend). Surprising because old DEG is
actually slower here (52 fps). Didn't see any regressions (and don't see
why they will happen), so let's ask our riggers and animators to perform
further speed tests ;)
Use atomic operations instead, should in theory improve timing of
scheduling. However, probably not so visible yet because actual
task scheduling still have some locks and memory allocations.
Baby steps, what would i say.
Currently a lot of the nodes in the new dependency graph are empty placeholders
for organizational purposes. These nodes would, however, still be assigned a task
which gets scheduled and takes up some time for worker threads to pop from the
queue and run. This can be avoided by skipping these nodes during depsgraph
scheduling, and scheduling their childrent right away. Gives a few percent speedup
in BlenRig.
This way it is possible to have single threaded depsgraph but threaded other areas
which is handy for torubleshooting.
he argument is: --debug-depsgraph-no-threads
This commit integrates the work done so far on the new dependency graph system,
where goal was to replace legacy depsgraph with the new one, supporting loads of
neat features like:
- More granular dependency relation nature, which solves issues with fake cycles
in the dependencies.
- Move towards all-animatable, by better integration of drivers into the system.
- Lay down some basis for upcoming copy-on-write, overrides and so on.
The new system is living side-by-side with the previous one and disabled by
default, so nothing will become suddenly broken. The way to enable new depsgraph
is to pass `--new-depsgraph` command line argument.
It's a bit early to consider the system production-ready, there are some TODOs
and issues were discovered during the merge period, they'll be addressed ASAP.
But it's important to merge, because it's the only way to attract artists to
really start testing this system.
There are number of assorted documents related on the design of the new system:
* http://wiki.blender.org/index.php/User:Aligorith/GSoC2013_Depsgraph#Design_Documents
* http://wiki.blender.org/index.php/User:Nazg-gul/DependencyGraph
There are also some user-related information online:
* http://code.blender.org/2015/02/blender-dependency-graph-branch-for-users/
* http://code.blender.org/2015/03/more-dependency-graph-tricks/
Kudos to everyone who was involved into the project:
- Joshua "Aligorith" Leung -- design specification, initial code
- Lukas "lukas_t" Toenne -- integrating code into blender, with further fixes
- Sergey "Sergey" "Sharybin" -- some mocking around, trying to wrap up the
project and so
- Bassam "slikdigit" Kurdali -- stressing the new system, reporting all the
issues and recording/writing documentation.
- Everyone else who i forgot to mention here :)
