Jeff King <peff@xxxxxxxx> writes: > Subject: [PATCH] packfile: actually set approximate_object_count_valid > > The approximate_object_count() function tries to compute the count only > once per process. But ever since it was introduced in 8e3f52d778 > (find_unique_abbrev: move logic out of get_short_sha1(), 2016-10-03), we > failed to actually set the "valid" flag, meaning we'd compute it fresh > on every call. > ... > Test origin HEAD > ---------------------------------------------------------------------------- > 5303.3: rev-list (1) 28.91(28.46+0.44) 29.03(28.65+0.38) +0.4% > 5303.4: abbrev-commit (1) 1.18(1.06+0.11) 1.17(1.02+0.14) -0.8% > 5303.7: rev-list (50) 28.95(28.56+0.38) 29.50(29.17+0.32) +1.9% > 5303.8: abbrev-commit (50) 3.67(3.56+0.10) 3.57(3.42+0.15) -2.7% > 5303.11: rev-list (1000) 30.34(29.89+0.43) 30.82(30.35+0.46) +1.6% > 5303.12: abbrev-commit (1000) 86.82(86.52+0.29) 77.82(77.59+0.22) -10.4% Yuk, this is quite extreme. > 5303.15: load 10,000 packs 0.08(0.02+0.05) 0.08(0.02+0.06) +0.0% > > It doesn't help at all when we have 1 pack (5303.4), but we get a 10% > speedup when there are 1000 packs (5303.12). That's a modest speedup for > a case that's already slow and we'd hope to avoid in general (note how > slow it is even after, because we have to look in each of those packs > for abbreviations). But it's a one-line change that clearly matches the > original intent, so it seems worth doing. > > The included perf test may also be useful for keeping an eye on any > regressions in the overall abbreviation code. > > Reported-by: Rasmus Villemoes <rv@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Jeff King <peff@xxxxxxxx> > --- > packfile.c | 1 + > t/perf/p5303-many-packs.sh | 4 ++++ > 2 files changed, 5 insertions(+) Thanks for finding and fixing. I agree that this is worth doing.
