Depsgraph: isolate node evaluation tasks
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Authored by Brecht Van Lommel (brecht) on Jun 22 2021, 8:07 PM.

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Reviewers

Sergey Sharybin (sergey)
Jacques Lucke (JacquesLucke)

Summary

Follow up to D11603. This changes causes threads to potentially evaluate
multiple objects recursively, which could be bad for performance and memory usage.

For example I encountered a case where the the stack trace was, which seems
pretty bad:

hair distribute
eval object
TBB wait
subdiv
eval object
TBB wait
subdiv
eval object

This potentially explains some uneven performance I was seeing, where loading
barbershop_interior.blend sometimes took 5x longer than usual. However more
performance and correctness testing is needed, since this re-introduces nested
isolation regions which may be problematic.

Diff Detail

Repository

rB Blender

Branch

isolate-depsgraph (branched from master)

Build Status

Buildable 15365
Build 15365: arc lint + arc unit

Event Timeline

Brecht Van Lommel (brecht) requested review of this revision.Jun 22 2021, 8:07 PM

Brecht Van Lommel (brecht) created this revision.

Harbormaster completed remote builds in B15365: Diff 38611.Jun 22 2021, 8:07 PM

Brecht Van Lommel (brecht) mentioned this in D11603: BLI: use explicit task isolation, no longer part of parallel operations.Jun 22 2021, 8:07 PM

Brecht Van Lommel (brecht) edited the summary of this revision. (Show Details)

I don't really have a better idea on how to solve this, so LGTM.
If I'm not mistaken, this shouldn't introduce new deadlocks (unless there is a bug in another place), because afaik evaluate_node(...) will not schedule any tasks that need to be executed by the task pool. The important thing here is that schedule_children(...)is not in the isolated region. Nested isolated regions themselves shouldn't be a cause for concern afaik.

This revision is now accepted and ready to land.Jun 23 2021, 9:38 AM

Unfortunately, this patch re-introduces the original issue with the 060_0010_A.lighting.blend from the production: P2203

Jacques Lucke (JacquesLucke) added 1 blocking reviewer(s): Sergey Sharybin (sergey).Jun 23 2021, 1:51 PM

This revision now requires review to proceed.Jun 23 2021, 1:51 PM