3 commits

Author	SHA1	Message	Date
Abhradeep Chakraborty	761416ef91	bitmap-lookup-table: add performance tests for lookup table ... Add performance tests to verify the performance of lookup table. `p5310-pack-bitmaps.sh` contain tests with and without lookup table. `p5312-pack-bitmaps-revs.sh` contain same tests with and without lookup table but with `pack.writeReverseIndex` enabled. Lookup table makes Git run faster in most of the cases. Below is the result of `t/perf/p5310-pack-bitmaps.sh`.`perf/p5326-multi-pack-bitmaps.sh` gives similar result. The repository used in the test is linux kernel. Test this tree ----------------------------------------------------------------------- 5310.4: enable lookup table: false 0.01(0.00+0.00) 5310.5: repack to disk 320.89(230.20+23.45) 5310.6: simulated clone 14.04(5.78+1.79) 5310.7: simulated fetch 1.95(3.05+0.20) 5310.8: pack to file (bitmap) 44.73(20.55+7.45) 5310.9: rev-list (commits) 0.78(0.46+0.10) 5310.10: rev-list (objects) 4.07(3.97+0.08) 5310.11: rev-list with tag negated via --not 0.06(0.02+0.03) --all (objects) 5310.12: rev-list with negative tag (objects) 0.21(0.15+0.05) 5310.13: rev-list count with blob:none 0.24(0.17+0.06) 5310.14: rev-list count with blob:limit=1k 7.07(5.92+0.48) 5310.15: rev-list count with tree:0 0.25(0.17+0.07) 5310.16: simulated partial clone 5.67(3.28+0.64) 5310.18: clone (partial bitmap) 16.05(8.34+1.86) 5310.19: pack to file (partial bitmap) 59.76(27.22+7.43) 5310.20: rev-list with tree filter (partial bitmap) 0.90(0.18+0.16) 5310.24: enable lookup table: true 0.01(0.00+0.00) 5310.25: repack to disk 319.73(229.30+23.01) 5310.26: simulated clone 13.69(5.72+1.78) 5310.27: simulated fetch 1.84(3.02+0.16) 5310.28: pack to file (bitmap) 45.63(20.67+7.50) 5310.29: rev-list (commits) 0.56(0.39+0.8) 5310.30: rev-list (objects) 3.77(3.74+0.08) 5310.31: rev-list with tag negated via --not 0.05(0.02+0.03) --all (objects) 5310.32: rev-list with negative tag (objects) 0.21(0.15+0.05) 5310.33: rev-list count with blob:none 0.23(0.17+0.05) 5310.34: rev-list count with blob:limit=1k 6.65(5.72+0.40) 5310.35: rev-list count with tree:0 0.23(0.16+0.06) 5310.36: simulated partial clone 5.57(3.26+0.59) 5310.38: clone (partial bitmap) 15.89(8.39+1.84) 5310.39: pack to file (partial bitmap) 58.32(27.55+7.47) 5310.40: rev-list with tree filter (partial bitmap) 0.73(0.18+0.15) Test 4-15 are tested without using lookup table. Same tests are repeated in 16-30 (using lookup table). Mentored-by: Taylor Blau <me@ttaylorr.com> Co-Mentored-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com> Signed-off-by: Abhradeep Chakraborty <chakrabortyabhradeep79@gmail.com> Reviewed-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	2022-08-26 10:14:02 -07:00
Jeff King	d4316604f8	pack-objects: default to writing bitmap hash-cache ... Enabling pack.writebitmaphashcache should always be a performance win. It costs only 4 bytes per object on disk, and the timings in ae4f07fbcc (pack-bitmap: implement optional name_hash cache, 2013-12-21) show it improving fetch and partial-bitmap clone times by 40-50%. The only reason we didn't enable it by default at the time is that early versions of JGit's bitmap reader complained about the presence of optional header bits it didn't understand. But that was changed in JGit's d2fa3987a (Use bitcheck to check for presence of OPT_FULL option, 2013-10-30), which made it into JGit v3.5.0 in late 2014. So let's turn this option on by default. It's backwards-compatible with all versions of Git, and if you are also using JGit on the same repository, you'd only run into problems using a version that's almost 5 years old. We'll drop the manual setting from all of our test scripts, including perf tests. This isn't strictly necessary, but it has two advantages: 1. If the hash-cache ever stops being enabled by default, our perf regression tests will notice. 2. We can use the modified perf tests to show off the behavior of an otherwise unconfigured repo, as shown below. These are the results of a few of a perf tests against linux.git that showed interesting results. You can see the expected speedup in 5310.4, which was noted in ae4f07fbcc. Curiously, 5310.8 did not improve (and actually got slower), despite seeing the opposite in ae4f07fbcc. I don't have an explanation for that. The tests from p5311 did not exist back then, but do show improvements (a smaller pack due to better deltas, which we found in less time). Test HEAD^ HEAD ------------------------------------------------------------------------------------- 5310.4: simulated fetch 7.39(22.70+0.25) 5.64(11.43+0.22) -23.7% 5310.8: clone (partial bitmap) 18.45(24.83+1.19) 19.94(28.40+1.36) +8.1% 5311.31: server (128 days) 0.41(1.13+0.05) 0.34(0.72+0.02) -17.1% 5311.32: size (128 days) 7.4M 7.0M -4.8% 5311.33: client (128 days) 1.33(1.49+0.06) 1.29(1.37+0.12) -3.0% Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	2019-03-18 14:11:15 +09:00
Jeff King	198b349da8	t/perf: add perf tests for fetches from a bitmapped server ... A server with bitmapped packs can serve a clone very quickly. However, fetches are not necessarily made any faster, because we spend a lot less time in object traversal (which is what bitmaps help with) and more time finding deltas (because we may have to throw out on-disk deltas if the client does not have the base). As a first step to making this faster, this patch introduces a new perf script to measure fetches into a repo of various ages from a fully-bitmapped server. We separately measure the work done by the server (in pack-objects) and that done by the client (in index-pack). Furthermore, we measure the size of the resulting pack. Breaking it down like this (instead of just doing a regular "git fetch") lets us see how much each side benefits from any changes. And since we know the pack size, if we estimate the network speed, then one could calculate a complete wall-clock time for the operation (though the script does not do this automatically). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	2018-08-20 14:04:47 -07:00