Hello Junio, On Thu, May 27, 2021 at 07:18:52AM +0900, Junio C Hamano wrote: > Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> writes: > > > It rebases clean on v5.10: > > > > $ time git rebase v5.10 > > Performing inexact rename detection: 100% (36806539/36806539), done. > > Performing inexact rename detection: 100% (36806539/36806539), done. > > Performing inexact rename detection: 100% (36806539/36806539), done. > > Performing inexact rename detection: 100% (36806539/36806539), done. > > Successfully rebased and updated detached HEAD. > > > > real 3m47.841s > > user 1m25.706s > > sys 0m11.181s > > > > If I start with the same rev checked out and explicitly specify the > > merge base, the rebase process is considerably faster: > > > > $ time git rebase --onto v5.10 v5.4 > > Performing inexact rename detection: 100% (36806539/36806539), done. > > Performing inexact rename detection: 100% (36806539/36806539), done. > > Performing inexact rename detection: 100% (36806539/36806539), done. > > Performing inexact rename detection: 100% (36806539/36806539), done. > > Successfully rebased and updated detached HEAD. > > > > real 1m20.588s > > user 1m12.645s > > sys 0m6.733s > > > > Is there some relevant complexity in the first invocation I'm not seeing > > that explains it takes more than the double time? I would have expected > > that > > > > git rebase v5.10 > > > > does the same as: > > > > git rebase --onto v5.10 $(git merge-base HEAD v5.10) > > There is a voodoo called fork-point detection that walks back the > reflogs and repeatedly computes merge bases, and giving --onto to > explicitly give a commit on which the history is transplanted should > remove the need to do the computation, so that is a possibility. > > But according to the manpage, it should not kick in for invocations > in the above example that specify the <upstream> (the > rebase.forkpoint configuration variable can clobber this default). FTR: I don't have this variable set in the two repositories that show the different timings. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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