Mercurial > hg
view tests/test-excessive-merge.t @ 44363:f7459da77f23
nodemap: introduce an option to use mmap to read the nodemap mapping
The performance and memory benefit is much greater if we don't have to copy all
the data in memory for each information. So we introduce an option (on by
default) to read the data using mmap.
This changeset is the last one definition the API for index support nodemap
data. (they have to be able to use the mmaping).
Below are some benchmark comparing the best we currently have in 5.3 with the
final step of this series (using the persistent nodemap implementation in
Rust). The benchmark run `hg perfindex` with various revset and the following
variants:
Before:
* do not use the persistent nodemap
* use the CPython implementation of the index for nodemap
* use mmapping of the changelog index
After:
* use the MixedIndex Rust code, with the NodeTree object for nodemap access
(still in review)
* use the persistent nodemap data from disk
* access the persistent nodemap data through mmap
* use mmapping of the changelog index
The persistent nodemap greatly speed up most operation on very large
repositories. Some of the previously very fast lookup end up a bit slower because
the persistent nodemap has to be setup. However the absolute slowdown is very
small and won't matters in the big picture.
Here are some numbers (in seconds) for the reference copy of mozilla-try:
Revset Before After abs-change speedup
-10000: 0.004622 0.005532 0.000910 × 0.83
-10: 0.000050 0.000132 0.000082 × 0.37
tip 0.000052 0.000085 0.000033 × 0.61
0 + (-10000:) 0.028222 0.005337 -0.022885 × 5.29
0 0.023521 0.000084 -0.023437 × 280.01
(-10000:) + 0 0.235539 0.005308 -0.230231 × 44.37
(-10:) + :9 0.232883 0.000180 -0.232703 ×1293.79
(-10000:) + (:99) 0.238735 0.005358 -0.233377 × 44.55
:99 + (-10000:) 0.317942 0.005593 -0.312349 × 56.84
:9 + (-10:) 0.313372 0.000179 -0.313193 ×1750.68
:9 0.316450 0.000143 -0.316307 ×2212.93
On smaller repositories, the cost of nodemap related operation is not as big, so
the win is much more modest. Yet it helps shaving a handful of millisecond here
and there.
Here are some numbers (in seconds) for the reference copy of mercurial:
Revset Before After abs-change speedup
-10: 0.000065 0.000097 0.000032 × 0.67
tip 0.000063 0.000078 0.000015 × 0.80
0 0.000561 0.000079 -0.000482 × 7.10
-10000: 0.004609 0.003648 -0.000961 × 1.26
0 + (-10000:) 0.005023 0.003715 -0.001307 × 1.35
(-10:) + :9 0.002187 0.000108 -0.002079 ×20.25
(-10000:) + 0 0.006252 0.003716 -0.002536 × 1.68
(-10000:) + (:99) 0.006367 0.003707 -0.002660 × 1.71
:9 + (-10:) 0.003846 0.000110 -0.003736 ×34.96
:9 0.003854 0.000099 -0.003755 ×38.92
:99 + (-10000:) 0.007644 0.003778 -0.003866 × 2.02
Differential Revision: https://phab.mercurial-scm.org/D7894
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Tue, 11 Feb 2020 11:18:52 +0100 |
parents | f1186c292d03 |
children | ccd76e292be5 |
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$ hg init $ echo foo > a $ echo foo > b $ hg add a b $ hg ci -m "test" $ echo blah > a $ hg ci -m "branch a" $ hg co 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo blah > b $ hg ci -m "branch b" created new head $ HGMERGE=true hg merge 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -m "merge b/a -> blah" $ hg co 1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ HGMERGE=true hg merge 2 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -m "merge a/b -> blah" created new head $ hg log changeset: 4:2ee31f665a86 tag: tip parent: 1:96155394af80 parent: 2:92cc4c306b19 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: merge a/b -> blah changeset: 3:e16a66a37edd parent: 2:92cc4c306b19 parent: 1:96155394af80 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: merge b/a -> blah changeset: 2:92cc4c306b19 parent: 0:5e0375449e74 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: branch b changeset: 1:96155394af80 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: branch a changeset: 0:5e0375449e74 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: test $ hg debugindex --changelog rev linkrev nodeid p1 p2 0 0 5e0375449e74 000000000000 000000000000 1 1 96155394af80 5e0375449e74 000000000000 2 2 92cc4c306b19 5e0375449e74 000000000000 3 3 e16a66a37edd 92cc4c306b19 96155394af80 4 4 2ee31f665a86 96155394af80 92cc4c306b19 revision 1 $ hg manifest --debug 1 79d7492df40aa0fa093ec4209be78043c181f094 644 a 2ed2a3912a0b24502043eae84ee4b279c18b90dd 644 b revision 2 $ hg manifest --debug 2 2ed2a3912a0b24502043eae84ee4b279c18b90dd 644 a 79d7492df40aa0fa093ec4209be78043c181f094 644 b revision 3 $ hg manifest --debug 3 79d7492df40aa0fa093ec4209be78043c181f094 644 a 79d7492df40aa0fa093ec4209be78043c181f094 644 b revision 4 $ hg manifest --debug 4 79d7492df40aa0fa093ec4209be78043c181f094 644 a 79d7492df40aa0fa093ec4209be78043c181f094 644 b $ hg debugindex a rev linkrev nodeid p1 p2 0 0 2ed2a3912a0b 000000000000 000000000000 1 1 79d7492df40a 2ed2a3912a0b 000000000000 $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 5 changesets with 4 changes to 2 files