On Thu, Aug 11, 2016 at 08:11:33AM -0700, Junio C Hamano wrote: > Jeff King <p...@peff.net> writes: > > > So considering "--depth" as a space-saving measure for --aggressive does > > not seem that effective. But it feels weird to quietly drop actions > > people might have done with previous aggressive runs. > > That argument cuts both ways, doesn't it? > > If the user explicitly asks to use lower "--depth" from the command > line when the second repack runs, the intention is clear: the > existing pack may use delta chains that are too long and is > detrimental to the run-time performance, and the user wants to > correct it by repacking with shorter delta chain. > > Should the act of letting "gc --auto" use lower "--depth", by not > configuring to always use deeper chain, be interpreted the same way? > I am not sure. The old packing with large --depth is something the > user did long time ago, and the decision the user made not to use > large depth always is also something the user did long time ago. I > do not think it is so cut-and-dried which one of the two conflicting > wishes we should honor when running the second repack, especially > when it is run unattended like "gc --auto" does.
Good points. Explicitly saying "repack --depth=..." carries a lot more weight to me than "git gc --auto" randomly kicking in, as far as knowing that what the user actually wants. My patch doesn't differentiate, of course, but I think it could. The other problem with my patch is the fact that we don't do a good job of finding new, in-limit deltas for the ones we discard. If you want to do that, you really need to "git repack -f" (at least with the current code). At which point we do not reuse the on-disk deltas at all, and the problem is moot (you could also interpret the fact that the user did _not_ pass "-f" as "you want to reuse deltas, which means you want to reuse even long chains", but as you've argued above, you can make a lot of guesses about the user's intention from what they did or did not say). So if we were to go this route, I don't think my patch is quite sufficient; we'd want something else on top to do a better job of finding replacement deltas. Regarding my "does not seem that effective" above, I think we should drop the aggressive depth to 50, and I just posted a patch with reasoning and numbers: http://public-inbox.org/git/20160811161309.ecmebaafcz6rk...@sigill.intra.peff.net/ That's maybe orthogonal, but it does remove the weird "gc --aggressive followed by gc --auto produces a bad pack" issue, because unless you are doing something clever, the depth will always be 50 (modulo people who did an aggressive pack with an older version of git :-/ ). -Peff -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
