Hi, On Tue, 16 Dec 2008, Jeff King wrote: > Johannes Schindelin's notes proposal (which is more or less > the current proposal, but I think the on-disk notes index was not > well liked): > http://thread.gmane.org/gmane.comp.version-control.git/52598 I redid the benchmark (this time with a bit beefier machine), just comparing no notes with David's/Peff's idea: -- snip -- $ GIT_NOTES_TIMING_TESTS=1 sh t3302-notes-index-expensive.sh -i -v Initialized empty Git repository in /home/gitte/git/t/trash directory.t3302-notes-index-expensive/.git/ * expecting success: create_repo 10 Initialized empty Git repository in /home/gitte/git/t/trash directory.t3302-notes-index-expensive/10/.git/ * ok 1: setup 10 * expecting success: test_notes 10 * ok 2: notes work * expecting success: time_notes 100 no-notes 0.08user 0.10system 0:00.18elapsed 95%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+58926minor)pagefaults 0swaps notes 0.14user 0.07system 0:00.54elapsed 38%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+60319minor)pagefaults 0swaps * ok 3: notes timing * expecting success: create_repo 100 Initialized empty Git repository in /home/gitte/git/t/trash directory.t3302-notes-index-expensive/100/.git/ * ok 1: setup 100 * expecting success: test_notes 100 * ok 2: notes work * expecting success: time_notes 100 no-notes 0.23user 0.21system 0:00.45elapsed 96%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+68043minor)pagefaults 0swaps notes 0.38user 0.21system 0:00.59elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+78829minor)pagefaults 0swaps * ok 3: notes timing * expecting success: create_repo 1000 Initialized empty Git repository in /home/gitte/git/t/trash directory.t3302-notes-index-expensive/1000/.git/ * ok 1: setup 1000 * expecting success: test_notes 1000 * ok 2: notes work * expecting success: time_notes 100 no-notes 2.06user 0.95system 0:04.26elapsed 70%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+159115minor)pagefaults 0swaps notes 2.83user 1.54system 0:04.38elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+267416minor)pagefaults 0swaps * ok 3: notes timing * expecting success: create_repo 10000 Initialized empty Git repository in /home/gitte/git/t/trash directory.t3302-notes-index-expensive/10000/.git/ * ok 1: setup 10000 * expecting success: test_notes 10000 * ok 2: notes work * expecting success: time_notes 100 no-notes 20.46user 7.63system 0:28.30elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+1083378minor)pagefaults 0swaps notes 28.78user 13.74system 0:42.85elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+2240296minor)pagefaults 0swaps * ok 3: notes timing * passed all 0 test(s) -- snap -- Keep in mind that the tests run "git log" 99 times, and show the accumulated time. So it seems that an increase of roughly 40% in the user time, and roughly 70% in the system time is the price to have notes associated with every single commit. Note that in that very same repository, a single "git show" goes from 0.00user 0.00system 0:00.00elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+561minor)pagefaults 0swaps to this: 0.03user 0.02system 0:00.04elapsed 113%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+2294minor)pagefaults 0swaps (In another run, it only used 90%CPU) That's not too shabby, given that Git needs to unpack double the number of objects in this test when using notes vs. no notes. For comparison, the numbers back then were something like 10% in user time with a penalty of an extraordinary magnitude everytime the notes are updated: around 800%. Note: all these numbers are worst-case numbers, i.e. every commit has one note. To be frank, I do not completely understand why the numbers are that high. I would have understood an increase roughly 4 seconds for reading the quite large tree 99 times, and then the same ~0.20 seconds back then. Maybe I made a huge mistake when implementing the thing. And BTW, my code does not yet handle the case when refs/notes/commits:$commit is a tree instead of a blob. That is left as an exercise to the reader. Johannes Schindelin (4): Introduce commit notes Add a script to edit/inspect notes Speed up git notes lookup Add an expensive test for git-notes .gitignore | 1 + Documentation/config.txt | 15 ++++ Documentation/git-notes.txt | 46 +++++++++++ Makefile | 3 + cache.h | 3 + command-list.txt | 1 + commit.c | 1 + config.c | 5 + environment.c | 1 + git-notes.sh | 65 +++++++++++++++ notes.c | 159 ++++++++++++++++++++++++++++++++++++++ notes.h | 7 ++ pretty.c | 5 + t/t3301-notes.sh | 65 +++++++++++++++ t/t3302-notes-index-expensive.sh | 98 +++++++++++++++++++++++ 15 files changed, 475 insertions(+), 0 deletions(-) create mode 100644 Documentation/git-notes.txt create mode 100755 git-notes.sh create mode 100644 notes.c create mode 100644 notes.h create mode 100755 t/t3301-notes.sh create mode 100755 t/t3302-notes-index-expensive.sh -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
