Re: [PATCH 00/14] Serialized Commit Graph
On 1/25/2018 6:06 PM, Ævar Arnfjörð Bjarmason wrote: On Thu, Jan 25 2018, Derrick Stolee jotted: Oops! This is my mistake. The correct command should be: git show-ref -s | git graph --write --update-head --stdin-commits Without "--stdin-commits" the command will walk all packed objects to look for commits and then build the graph. That's why it's taking so long. That method takes several minutes on the Linux repo, but with --stdin-commits it should take as long as "git log >/dev/null". Thanks, it took around 15m to finish with the command I initially ran on my test repo. Then the `merge-base --is-ancestor` performance problem I was complaining about in https://public-inbox.org/git/87608bawoa@evledraar.gmail.com/ takes around 1s with your series, 5s without it. Nice. Thanks for testing this! May I ask how many commits are in your repo? One way to find out is to run 'git graph --read' and it will tell you how many commits are in the serialized graph. Thanks, -Stolee
Re: [PATCH 00/14] Serialized Commit Graph
On Thu, Jan 25 2018, Derrick Stolee jotted: > On 1/25/2018 10:46 AM, Ævar Arnfjörð Bjarmason wrote: >> On Thu, Jan 25 2018, Derrick Stolee jotted: >> >>> * 'git log --topo-order -1000' walks all reachable commits to avoid >>>incorrect topological orders, but only needs the commit message for >>>the top 1000 commits. >>> >>> * 'git merge-base ' may walk many commits to find the correct >>>boundary between the commits reachable from A and those reachable >>>from B. No commit messages are needed. >>> >>> * 'git branch -vv' checks ahead/behind status for all local branches >>>compared to their upstream remote branches. This is essentially as >>>hard as computing merge bases for each. >> This is great, spotted / questions so far: >> >> * git graph --blah says you need to enable the config, should say >>"unknown option --blah ". I.e. overzelous config guard. > > This is a good point. > >> * On a big repo (git show-ref -s | ~/g/git/git-graph --write >>--update-head) is as of writing this still hanging for me, but strace >>shows it's brk()-ing. Presumably just still busy, a progress bar would >>be very nice. > > Oops! This is my mistake. The correct command should be: > > git show-ref -s | git graph --write --update-head --stdin-commits > > Without "--stdin-commits" the command will walk all packed objects > to look for commits and then build the graph. That's why it's taking > so long. That method takes several minutes on the Linux repo, but with > --stdin-commits it should take as long as "git log >/dev/null". Thanks, it took around 15m to finish with the command I initially ran on my test repo. Then the `merge-base --is-ancestor` performance problem I was complaining about in https://public-inbox.org/git/87608bawoa@evledraar.gmail.com/ takes around 1s with your series, 5s without it. Nice.
Re: [PATCH 00/14] Serialized Commit Graph
On 1/25/2018 10:46 AM, Ævar Arnfjörð Bjarmason wrote: On Thu, Jan 25 2018, Derrick Stolee jotted: * 'git log --topo-order -1000' walks all reachable commits to avoid incorrect topological orders, but only needs the commit message for the top 1000 commits. * 'git merge-base ' may walk many commits to find the correct boundary between the commits reachable from A and those reachable from B. No commit messages are needed. * 'git branch -vv' checks ahead/behind status for all local branches compared to their upstream remote branches. This is essentially as hard as computing merge bases for each. This is great, spotted / questions so far: * git graph --blah says you need to enable the config, should say "unknown option --blah ". I.e. overzelous config guard. This is a good point. * On a big repo (git show-ref -s | ~/g/git/git-graph --write --update-head) is as of writing this still hanging for me, but strace shows it's brk()-ing. Presumably just still busy, a progress bar would be very nice. Oops! This is my mistake. The correct command should be: git show-ref -s | git graph --write --update-head --stdin-commits Without "--stdin-commits" the command will walk all packed objects to look for commits and then build the graph. That's why it's taking so long. That method takes several minutes on the Linux repo, but with --stdin-commits it should take as long as "git log >/dev/null". * Shouldn't there be a pack.useGraph option so this gets auto-updated on repack? I understand this series is a WIP, so that's more a "is that the UI" than "it needs now". This will definitely be part of a follow-up patch. Thanks, -Stolee
Re: [PATCH 00/14] Serialized Commit Graph
On Thu, Jan 25 2018, Derrick Stolee jotted: > * 'git log --topo-order -1000' walks all reachable commits to avoid > incorrect topological orders, but only needs the commit message for > the top 1000 commits. > > * 'git merge-base ' may walk many commits to find the correct > boundary between the commits reachable from A and those reachable > from B. No commit messages are needed. > > * 'git branch -vv' checks ahead/behind status for all local branches > compared to their upstream remote branches. This is essentially as > hard as computing merge bases for each. This is great, spotted / questions so far: * git graph --blah says you need to enable the config, should say "unknown option --blah ". I.e. overzelous config guard. * On a big repo (git show-ref -s | ~/g/git/git-graph --write --update-head) is as of writing this still hanging for me, but strace shows it's brk()-ing. Presumably just still busy, a progress bar would be very nice. * Shouldn't there be a pack.useGraph option so this gets auto-updated on repack? I understand this series is a WIP, so that's more a "is that the UI" than "it needs now".
[PATCH 00/14] Serialized Commit Graph
As promised [1], this patch contains a way to serialize the commit graph. The current implementation defines a new file format to store the graph structure (parent relationships) and basic commit metadata (commit date, root tree OID) in order to prevent parsing raw commits while performing basic graph walks. For example, we do not need to parse the full commit when performing these walks: * 'git log --topo-order -1000' walks all reachable commits to avoid incorrect topological orders, but only needs the commit message for the top 1000 commits. * 'git merge-base ' may walk many commits to find the correct boundary between the commits reachable from A and those reachable from B. No commit messages are needed. * 'git branch -vv' checks ahead/behind status for all local branches compared to their upstream remote branches. This is essentially as hard as computing merge bases for each. The current patch speeds up these calculations by injecting a check in parse_commit_gently() to check if there is a graph file and using that to provide the required metadata to the struct commit. The file format has room to store generation numbers, which will be provided as a patch after this framework is merged. Generation numbers are referenced by the design document but not implemented in order to make the current patch focus on the graph construction process. Once that is stable, it will be easier to add generation numbers and make graph walks aware of generation numbers one-by-one. Here are some performance results for a copy of the Linux repository where 'master' has 704,766 reachable commits and is behind 'origin/master' by 19,610 commits. | Command | Before | After | Rel % | |--|||---| | log --oneline --topo-order -1000 | 5.9s | 0.7s | -88% | | branch -vv | 0.42s | 0.27s | -35% | | rev-list --all | 6.4s | 1.0s | -84% | | rev-list --all --objects | 32.6s | 27.6s | -15% | To test this yourself, run the following on your repo: git config core.graph true git show-ref -s | git graph --write --update-head The second command writes a commit graph file containing every commit reachable from your refs. Now, all git commands that walk commits will check your graph first before consulting the ODB. You can run your own performance comparisions by toggling the 'core.graph' setting. [1] https://public-inbox.org/git/d154319e-bb9e-b300-7c37-27b1dcd2a...@jeffhostetler.com/ Re: What's cooking in git.git (Jan 2018, #03; Tue, 23) [2] https://github.com/derrickstolee/git/pull/2 A GitHub pull request containing the latest version of this patch. P.S. I'm sending this patch from my gmail address to avoid Outlook munging the URLs included in the design document. Derrick Stolee (14): graph: add packed graph design document packed-graph: add core.graph setting packed-graph: create git-graph builtin packed-graph: add format document packed-graph: implement construct_graph() packed-graph: implement git-graph --write packed-graph: implement git-graph --read graph: implement git-graph --update-head packed-graph: implement git-graph --clear packed-graph: teach git-graph --delete-expired commit: integrate packed graph with commit parsing packed-graph: read only from specific pack-indexes packed-graph: close under reachability packed-graph: teach git-graph to read commits Documentation/config.txt | 3 + Documentation/git-graph.txt | 102 Documentation/technical/graph-format.txt | 88 Documentation/technical/packed-graph.txt | 185 +++ Makefile | 2 + alloc.c | 1 + builtin.h| 1 + builtin/graph.c | 231 + cache.h | 1 + command-list.txt | 1 + commit.c | 20 +- commit.h | 2 + config.c | 5 + environment.c| 1 + git.c| 1 + log-tree.c | 3 +- packed-graph.c | 840 +++ packed-graph.h | 65 +++ packfile.c | 4 +- packfile.h | 2 + t/t5319-graph.sh | 271 ++ 21 files changed, 1822 insertions(+), 7 deletions(-) create mode 100644 Documentation/git-graph.txt create mode 100644 Documentation/technical/graph-format.txt create mode 100644 Documentation/technical/packed-graph.txt create mode 100644 builtin/graph.c create mode 100644 packed-graph.c create mode 100644 packed-graph.h create mode 100755 t/t5319-graph.sh --
