git/list[1] front-page[2] threads[3] people[4] search[5] about
 

Re: [PATCH 2/2] pack-objects: optimize "recency order"

From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date
Oct 27, 2011, 21:01 UTC
Message-ID
<CACBZZX6Ss4jLtdrDhLUNKCUjEHjHHKzfv-LMkOyTPDhRUXm4sQ@mail.gmail.com>
In-Reply-To
<1310084657-16790-3-git-send-email-gitster@pobox.com>
On Fri, Jul 8, 2011 at 02:24, Junio C Hamano <gitster@pobox.com> wrote:
>  - Commits at the tip of tags are written together, in the hope that
>   revision traversal done in incremental fetch (which starts by
>   putting them in a revision queue marked as UNINTERESTING) will see a
>   better locality of these objects;

We recently upgraded to 1.7.7 and I've traced a very large slowdown in packing down to this commit.

On our repository packing used to take around 30 seconds, it now takes about 4 minutes. Which means that cloning the repository went from being slightly slow to pretty intolerable.

I haven't dug into why this is but I'm pretty sure it's because this patch makes Git behave pathologically on repositories with a large amount of tags. git.git itself has ~27k revs / and ~450 tags, or a tag every ~60 revisions.

Try it on e.g. a repository with a couple of hundred thousand revs and a tag every 10-20 revisions.

Previous: Shawn PearceNext: Ævar Arnfjörð Bjarmason
Message 9 of 14 in “For improved pack locality”
  1. 0/2 For improved pack localityJunio C Hamano, Jul 8, 2011
  2. 1/2 core: log offset pack data accesses happenedJunio C Hamano, Jul 8, 2011
  3. 2/2 pack-objects: optimize "recency order"Junio C Hamano, Jul 8, 2011
  4. Shawn PearceJul 8, 2011
  5. Junio C HamanoJul 8, 2011
  6. Nicolas PitreJul 11, 2011
  7. Junio C HamanoJul 8, 2011
  8. Shawn PearceJul 9, 2011
  9. Ævar Arnfjörð BjarmasonOct 27, 2011
  10. Ævar Arnfjörð BjarmasonOct 27, 2011
  11. Ævar Arnfjörð BjarmasonOct 27, 2011
  12. Jakub NarebskiOct 27, 2011
  13. Junio C HamanoOct 27, 2011
  14. Ævar Arnfjörð BjarmasonOct 28, 2011

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.