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author | Colin Stolley <cstolley@runbox.com> | 2019-11-27 16:24:53 -0600 |
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committer | Junio C Hamano <gitster@pobox.com> | 2019-12-03 07:59:45 -0800 |
commit | ec48540fe8c387cf7424d5387ddbd53e89bb9d51 (patch) | |
tree | 1b2111770e24c35a2591d4458c6c6e3fba124e8b /Documentation/RelNotes/1.8.4.txt | |
parent | The first batch post 2.24 cycle (diff) | |
download | tgif-ec48540fe8c387cf7424d5387ddbd53e89bb9d51.tar.xz |
packfile.c: speed up loading lots of packfiles
When loading packfiles on start-up, we traverse the internal packfile
list once per file to avoid reloading packfiles that have already
been loaded. This check runs in quadratic time, so for poorly
maintained repos with a large number of packfiles, it can be pretty
slow.
Add a hashmap containing the packfile names as we load them so that
the average runtime cost of checking for already-loaded packs becomes
constant.
Add a perf test to p5303 to show speed-up.
The existing p5303 test runtimes are dominated by other factors and do
not show an appreciable speed-up. The new test in p5303 clearly exposes
a speed-up in bad cases. In this test we create 10,000 packfiles and
measure the start-up time of git rev-parse, which does little else
besides load in the packs.
Here are the numbers for the new p5303 test:
Test HEAD^ HEAD
---------------------------------------------------------------------
5303.12: load 10,000 packs 1.03(0.92+0.10) 0.12(0.02+0.09) -88.3%
Signed-off-by: Colin Stolley <cstolley@runbox.com>
Helped-by: Jeff King <peff@peff.net>
[jc: squashed the change to call hashmap in install_packed_git() by peff]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation/RelNotes/1.8.4.txt')
0 files changed, 0 insertions, 0 deletions