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Re: [PATCH 0/4] Honor core.deltaBaseCacheLimit during index-pack

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Jul 14, 2008, 12:25 UTC
Message-ID
<alpine.DEB.1.00.0807141322140.8950@racer>
In-Reply-To
<487B439F.8040902@op5.se>
Hi,
On Mon, 14 Jul 2008, Andreas Ericsson wrote:
Show 5 quoted lines
> Sorry for being clueless here, but why does the older versions need
> to be kept in-memory anyway? Aren't we applying the delta each time
> we find one, repeatedly creating a new base-object in-memory for
> each delta? If we aren't doing that, why do we need more than just
> a small amount of memory just for keeping the delta?

Think of a delta chain of 49 delta objects, 1 base object. Now reconstruct all of the objects.

If you do it one by one, not storing the intermediate results, you end up applying 1 delta for the first, 2 for the second (first the first, then the second), and so on, in total 1 + 2 + 3 + ... + 49 = 49 * 50 / 2 = 1225 times.

Compare that to the 49 times when reusing the intermediate results.

Ciao, Dscho

Previous: Andreas EricssonNext: Andreas Ericsson
Message 38 of 51 in “git pull is slow”
  1. Stephan HennigJul 10, 2008
  2. Martin LanghoffJul 10, 2008
  3. Petr BaudisJul 10, 2008
  4. Johannes SixtJul 10, 2008
  5. Stephan HennigJul 10, 2008
  6. Petr BaudisJul 10, 2008
  7. Stephan HennigJul 10, 2008
  8. Stephan HennigJul 11, 2008
  9. Andreas EricssonJul 11, 2008
  10. Johannes SchindelinJul 11, 2008
  11. Stephan HennigJul 12, 2008
  12. Johannes SchindelinJul 12, 2008
  13. Shawn O. PearceJul 13, 2008
  14. Johannes SchindelinJul 13, 2008
  15. Shawn O. PearceJul 13, 2008
  16. 0/4 Honor core.deltaBaseCacheLimit during index-packShawn O. Pearce, Jul 14, 2008
  17. 1/4 index-pack: Refactor base arguments of resolve_delta into a structShawn O. Pearce, Jul 14, 2008
  18. 2/4 index-pack: Chain the struct base_data on the stack for traversalShawn O. Pearce, Jul 14, 2008
  19. 3/4 index-pack: Track the object_entry that creates each base_dataShawn O. Pearce, Jul 14, 2008
  20. 4/4 index-pack: Honor core.deltaBaseCacheLimit when resolving deltasShawn O. Pearce, Jul 14, 2008
  21. Nicolas PitreJul 15, 2008
  22. Shawn O. PearceJul 15, 2008
  23. index-pack: Honor core.deltaBaseCacheLimit when resolving deltasShawn O. Pearce, Jul 15, 2008
  24. Nicolas PitreJul 15, 2008
  25. Junio C HamanoJul 15, 2008
  26. Johannes SchindelinJul 14, 2008
  27. Nicolas PitreJul 15, 2008
  28. Shawn O. PearceJul 15, 2008
  29. Nicolas PitreJul 15, 2008
  30. Nicolas PitreJul 15, 2008
  31. Nicolas PitreJul 15, 2008
  32. Nicolas PitreJul 14, 2008
  33. Shawn O. PearceJul 14, 2008
  34. Johannes SchindelinJul 14, 2008
  35. Jakub NarebskiJul 14, 2008
  36. Johannes SchindelinJul 14, 2008
  37. Andreas EricssonJul 14, 2008
  38. Johannes SchindelinJul 14, 2008
  39. Andreas EricssonJul 14, 2008
  40. Johannes SchindelinJul 14, 2008
  41. Nicolas PitreJul 15, 2008
  42. Shawn O. PearceJul 15, 2008
  43. Nicolas PitreJul 15, 2008
  44. Stephan HennigJul 17, 2008
  45. Nicolas PitreJul 17, 2008
  46. Shawn O. PearceJul 17, 2008
  47. index-pack: Issue a warning if deltaBaseCacheLimit is too smallShawn O. Pearce, Jul 17, 2008
  48. Nicolas PitreJul 17, 2008
  49. Shawn O. PearceJul 15, 2008
  50. Stephan HennigJul 13, 2008
  51. Stephan HennigJul 11, 2008

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