Mercurial > hg
view tests/test-ui-verbosity.py.out @ 42743:8c9a6adec67a
rust-discovery: using the children cache in add_missing
The DAG range computation often needs to get back to very old
revisions, and turns out to be disproportionately long, given
that the end goal is to remove the descendents of the given
missing revisons from the undecided set.
The fast iteration capabilities available in the Rust case make
it possible to avoid the DAG range entirely, at the cost of
precomputing the children cache, and to simply iterate on
children of the given missing revisions.
This is a case where staying on the same side of the interface
between the two languages has clear benefits.
On discoveries with initial undecided sets
small enough to bypass sampling entirely, the total cost of
computing the children cache and the subsequent iteration
becomes better than the Python + C counterpart, which relies on
reachableroots2.
For example, on a repo with more than one million revisions with
an initial undecided set of 11 elements, we get these figures:
Rust version with simple iteration
addcommons: 57.287us
first undecided computation: 184.278334ms
first children cache computation: 131.056us
addmissings iteration: 42.766us
first addinfo total: 185.24 ms
Python + C version
first addcommons: 0.29 ms
addcommons 0.21 ms
first undecided computation 191.35 ms
addmissings 45.75 ms
first addinfo total: 237.77 ms
On discoveries with large undecided sets, the initial price paid
makes the first addinfo slower than the Python + C version,
but that's more than compensated by the gain in sampling and
subsequent iterations.
Here's an extreme example with an undecided set of a million revisions:
Rust version:
first undecided computation: 293.842629ms
first children cache computation: 407.911297ms
addmissings iteration: 34.312869ms
first addinfo total: 776.02 ms
taking initial sample
query 2: sampling time: 1318.38 ms
query 2; still undecided: 1005013, sample size is: 200
addmissings: 143.062us
Python + C version:
first undecided computation 298.13 ms
addmissings 80.13 ms
first addinfo total: 399.62 ms
taking initial sample
query 2: sampling time: 3957.23 ms
query 2; still undecided: 1005013, sample size is: 200
addmissings 52.88 ms
Differential Revision: https://phab.mercurial-scm.org/D6428
| author | Georges Racinet <georges.racinet@octobus.net> |
|---|---|
| date | Tue, 16 Apr 2019 01:16:39 +0200 |
| parents | 807f3f5c60e9 |
| children |
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hgrc settings command line options final result quiet verbo debug quiet verbo debug quiet verbo debug 0 False False False False False False -> False False False 1 True False False False False False -> True False False 2 False True False False False False -> False True False 3 True True False False False False -> False False False 4 False False True False False False -> False True True 5 True False True False False False -> False True True 6 False True True False False False -> False True True 7 True True True False False False -> False True True 8 False False False True False False -> True False False 9 True False False True False False -> True False False 10 False True False True False False -> True False False 11 True True False True False False -> True False False 12 False False True True False False -> True False False 13 True False True True False False -> True False False 14 False True True True False False -> True False False 15 True True True True False False -> True False False 16 False False False False True False -> False True False 17 True False False False True False -> False True False 18 False True False False True False -> False True False 19 True True False False True False -> False True False 20 False False True False True False -> False True False 21 True False True False True False -> False True False 22 False True True False True False -> False True False 23 True True True False True False -> False True False 24 False False False True True False -> False False False 25 True False False True True False -> False False False 26 False True False True True False -> False False False 27 True True False True True False -> False False False 28 False False True True True False -> False False False 29 True False True True True False -> False False False 30 False True True True True False -> False False False 31 True True True True True False -> False False False 32 False False False False False True -> False True True 33 True False False False False True -> False True True 34 False True False False False True -> False True True 35 True True False False False True -> False True True 36 False False True False False True -> False True True 37 True False True False False True -> False True True 38 False True True False False True -> False True True 39 True True True False False True -> False True True 40 False False False True False True -> False True True 41 True False False True False True -> False True True 42 False True False True False True -> False True True 43 True True False True False True -> False True True 44 False False True True False True -> False True True 45 True False True True False True -> False True True 46 False True True True False True -> False True True 47 True True True True False True -> False True True 48 False False False False True True -> False True True 49 True False False False True True -> False True True 50 False True False False True True -> False True True 51 True True False False True True -> False True True 52 False False True False True True -> False True True 53 True False True False True True -> False True True 54 False True True False True True -> False True True 55 True True True False True True -> False True True 56 False False False True True True -> False True True 57 True False False True True True -> False True True 58 False True False True True True -> False True True 59 True True False True True True -> False True True 60 False False True True True True -> False True True 61 True False True True True True -> False True True 62 False True True True True True -> False True True 63 True True True True True True -> False True True