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Re: [RFC] pack-objects: compression level for non-blobs

From
Junio C Hamano <gitster@pobox.com>
Date
Jan 1, 2013, 20:02 UTC
Message-ID
<7v7gnwbrjf.fsf@alter.siamese.dyndns.org>
In-Reply-To
<CACsJy8DpnO6X6jdQVsr1NwrXF2MDBBcHZQTay=TyLFc5p_z9eg@mail.gmail.com>
Duy Nguyen <pclouds@gmail.com> writes:
Show 12 quoted lines
> On Tue, Jan 1, 2013 at 11:15 AM, Duy Nguyen <pclouds@gmail.com> wrote:
>>> Fix pack-objects to behave the way JGit does, cluster commits first in
>>> the pack stream. Now you have a dense space of commits. If I remember
>>> right this has a tiny positive improvement for most rev-list
>>> operations with very little downside.
>>
>> I was going to suggest a similar thing. The current state of C Git's
>> pack writing is not bad. We mix commits and tags together, but tags
>
> And I was wrong. At least since 1b4bb16 (pack-objects: optimize
> "recency order" - 2011-06-30) commits are spread out and can be mixed
> with trees too.
Really?  That certainly wasn't the intention of that change.

The compute_write_order() function first fills the commits in the original recency order (the order in which rev-list discovered them by traversing the history from the tips) until we find a commit that is tagged by a ref in the refs/tags/ hierarchy. When we reach that point, we stop showing the commits and show all the tags in the refs/tags/ hierarchy and commits that are tagged by them, breaking the original ordering of commits so that ancient but tagged commits clump at this point. After that, we resume showing the rest of the commits and tags in the original order they came to us. Trees are done next, and then the remainder.

So I am not sure how trees can appear between commits.
Previous: Duy Nguyen
Message 19 of 19 in “[RFC] pack-objects: compression level for non-blobs”
  1. David Michael BarrNov 26, 2012
  2. David Michael BarrNov 26, 2012
  3. Jeff KingDec 29, 2012
  4. Nguyen Thai Ngoc DuyDec 29, 2012
  5. Jeff KingDec 29, 2012
  6. Nguyen Thai Ngoc DuyDec 29, 2012
  7. Jeff KingDec 29, 2012
  8. Jeff KingDec 29, 2012
  9. Jeff KingDec 29, 2012
  10. Jeff KingDec 30, 2012
  11. Nguyen Thai Ngoc DuyDec 30, 2012
  12. Jeff KingDec 30, 2012
  13. Shawn PearceDec 31, 2012
  14. Duy NguyenJan 1, 2013
  15. Duy NguyenJan 1, 2013
  16. Shawn PearceJan 1, 2013
  17. Junio C HamanoJan 1, 2013
  18. Duy NguyenJan 2, 2013
  19. Junio C HamanoJan 1, 2013

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