Derrick Stolee <dstolee@xxxxxxxxxxxxx> writes: > p0008.1: find_unique_abbrev() for existing objects > -------------------------------------------------- > > For 10 repeated tests, each checking 100,000 known objects, we find the > following results when running in a Linux VM: > > | | Pack | Packed | Loose | Base | New | | > | Repo | Files | Objects | Objects| Time | Time | Rel% | > |-------|-------|---------|--------|--------|--------|---------| > | Git | 1 | 230078 | 0 | 0.09 s | 0.06 s | - 33.3% | > | Git | 5 | 230162 | 0 | 0.11 s | 0.08 s | - 27.3% | > | Git | 4 | 154310 | 75852 | 0.09 s | 0.07 s | - 22.2% | > | Linux | 1 | 5606645 | 0 | 0.12 s | 0.32 s | +146.2% | > | Linux | 24 | 5606645 | 0 | 1.12 s | 1.12 s | - 0.9% | > | Linux | 23 | 5283204 | 323441 | 1.08 s | 1.05 s | - 2.8% | > | VSTS | 1 | 4355923 | 0 | 0.12 s | 0.23 s | + 91.7% | > | VSTS | 32 | 4355923 | 0 | 1.02 s | 1.08 s | + 5.9% | > | VSTS | 31 | 4276829 | 79094 | 2.25 s | 2.08 s | - 7.6% | The above does not look so good, especially in cases where a repository is well maintained by packing into smaller number of packs, we get much worse result? > p0008.2: find_unique_abbrev() for missing objects > ------------------------------------------------- > > For 10 repeated tests, each checking 100,000 missing objects, we find > the following results when running in a Linux VM: > > | | Pack | Packed | Loose | Base | New | | > | Repo | Files | Objects | Objects| Time | Time | Rel% | > |-------|-------|---------|--------|--------|--------|--------| > | Git | 1 | 230078 | 0 | 0.66 s | 0.08 s | -87.9% | > | Git | 5 | 230162 | 0 | 0.90 s | 0.13 s | -85.6% | > | Git | 4 | 154310 | 75852 | 0.79 s | 0.10 s | -87.3% | > | Linux | 1 | 5606645 | 0 | 0.48 s | 0.32 s | -33.3% | > | Linux | 24 | 5606645 | 0 | 4.41 s | 1.09 s | -75.3% | > | Linux | 23 | 5283204 | 323441 | 4.11 s | 0.99 s | -75.9% | > | VSTS | 1 | 4355923 | 0 | 0.46 s | 0.25 s | -45.7% | > | VSTS | 32 | 4355923 | 0 | 5.40 s | 1.15 s | -78.7% | > | VSTS | 31 | 4276829 | 79094 | 5.88 s | 1.18 s | -79.9% | The question is if this is even measuring a relevant workload. How often would we have a full 40-hex object name for which we actually do not have the object, and ask its name to be abbreviated? Compared to it, the result from p0008.1 feels a lot more important. We know we make tons of "abbreviate the object name for this object we have" and we see them every day in our "git log -p" output. Seeing a lot more impressive result from p0008.2 than p0008.1 makes me unsure if this patch is optimizing for the right case. I'll have to see the code a bit deeper before I can comment on it. Thanks.
