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Diffstat (limited to 'Documentation/technical/pack-heuristics.txt')
| -rw-r--r-- | Documentation/technical/pack-heuristics.txt | 32 |
1 files changed, 13 insertions, 19 deletions
diff --git a/Documentation/technical/pack-heuristics.txt b/Documentation/technical/pack-heuristics.txt index 103eb5d989..95a07db6e8 100644 --- a/Documentation/technical/pack-heuristics.txt +++ b/Documentation/technical/pack-heuristics.txt @@ -1,15 +1,15 @@ - Concerning Git's Packing Heuristics - =================================== +Concerning Git's Packing Heuristics +=================================== Oh, here's a really stupid question: Where do I go to learn the details - of git's packing heuristics? + of Git's packing heuristics? Be careful what you ask! -Followers of the git, please open the git IRC Log and turn to +Followers of the Git, please open the Git IRC Log and turn to February 10, 2006. It's a rare occasion, and we are joined by the King Git Himself, @@ -19,7 +19,7 @@ and seeks enlightenment. Others are present, but silent. Let's listen in! <njs`> Oh, here's a really stupid question -- where do I go to - learn the details of git's packing heuristics? google avails + learn the details of Git's packing heuristics? google avails me not, reading the source didn't help a lot, and wading through the whole mailing list seems less efficient than any of that. @@ -37,7 +37,7 @@ Ah! Modesty after all. <linus> njs, I don't think the docs exist. That's something where I don't think anybody else than me even really got involved. - Most of the rest of git others have been busy with (especially + Most of the rest of Git others have been busy with (especially Junio), but packing nobody touched after I did it. It's cryptic, yet vague. Linus in style for sure. Wise men @@ -57,7 +57,7 @@ Bait... And switch. That ought to do it! - <linus> Remember: git really doesn't follow files. So what it does is + <linus> Remember: Git really doesn't follow files. So what it does is - generate a list of all objects - sort the list according to magic heuristics - walk the list, using a sliding window, seeing if an object @@ -89,7 +89,7 @@ Ah, grasshopper! And thus the enlightenment begins anew. <linus> The "magic" is actually in theory totally arbitrary. ANY order will give you a working pack, but no, it's not - ordered by SHA1. + ordered by SHA-1. Before talking about the ordering for the sliding delta window, let's talk about the recency order. That's more @@ -366,12 +366,6 @@ been detailed! <linus> Yes, we always write out most recent first -For the other record: - - <pasky> njs`: http://pastebin.com/547965 - -The 'net never forgets, so that should be good until the end of time. - <njs`> And, yeah, I got the part about deeper-in-history stuff having worse IO characteristics, one sort of doesn't care. @@ -382,7 +376,7 @@ The 'net never forgets, so that should be good until the end of time. <njs`> (if only it happened more...) <linus> Anyway, the pack-file could easily be denser still, but - because it's used both for streaming (the git protocol) and + because it's used both for streaming (the Git protocol) and for on-disk, it has a few pessimizations. Actually, it is a made-up word. But it is a made-up word being @@ -432,12 +426,12 @@ Gasp! OK, saved. That's a fair Engineering trade off. Close call! In fact, Linus reflects on some Basic Engineering Fundamentals, design options, etc. - <linus> More importantly, they allow git to still _conceptually_ + <linus> More importantly, they allow Git to still _conceptually_ never deal with deltas at all, and be a "whole object" store. Which has some problems (we discussed bad huge-file - behaviour on the git lists the other day), but it does mean - that the basic git concepts are really really simple and + behaviour on the Git lists the other day), but it does mean + that the basic Git concepts are really really simple and straightforward. It's all been quite stable. @@ -461,6 +455,6 @@ Nuff said. <njs`> :-) <njs`> appreciate the infodump, I really was failing to find the - details on git packs :-) + details on Git packs :-) And now you know the rest of the story. |