I'm afraid I cannot reproduce the segfault locally (assuming you're
performing the rev-list on the git/git repository). Could you please
send me more information, and a core dump if possible?
On Tue, Jun 25, 2013 at 6:22 PM, Thomas Rast <tr...@inf.ethz.ch> wrote:
> Vicent Marti <tan...@gmail.com> writes:
>
>> Calling `git rev-list --use-bitmaps [committish]` is the equivalent
>> of `git rev-list --objects`, but the rev list is performed based on
>> a bitmap result instead of using a manual counting objects phase.
>
> Why would we ever want to not --use-bitmaps, once it actually works?
> I.e., shouldn't this be the default if pack.usebitmaps is set (or
> possibly even core.usebitmaps for these things)?
>
>> These are some example timings for `torvalds/linux`:
>>
>> $ time ../git/git rev-list --objects master > /dev/null
>>
>> real 0m25.567s
>> user 0m25.148s
>> sys 0m0.384s
>>
>> $ time ../git/git rev-list --use-bitmaps master > /dev/null
>>
>> real 0m0.393s
>> user 0m0.356s
>> sys 0m0.036s
>
> I see your badass numbers, and raise you a critical issue:
>
> $ time git rev-list --use-bitmaps --count --left-right
> origin/pu...origin/next
> Segmentation fault
>
> real 0m0.408s
> user 0m0.383s
> sys 0m0.022s
>
> It actually seems to be related solely to having negated commits in the
> walk:
>
> thomas@linux-k42r:~/g(next u+65)$ time git rev-list --use-bitmaps --count
> origin/pu
> 32315
>
> real 0m0.041s
> user 0m0.034s
> sys 0m0.006s
> thomas@linux-k42r:~/g(next u+65)$ time git rev-list --use-bitmaps --count
> origin/pu ^origin/next
> Segmentation fault
>
> real 0m0.460s
> user 0m0.214s
> sys 0m0.244s
>
> I also can't help noticing that the time spent generating the segfault
> would have sufficed to generate the answer "the old way" as well:
>
> $ time git rev-list --count --left-right origin/pu...origin/next
> 189 125
>
> real 0m0.409s
> user 0m0.386s
> sys 0m0.022s
>
> Can we use the same trick to speed up merge base computation and then
> --left-right? The latter is a component of __git_ps1 and can get
> somewhat slow in some cases, so it would be nice to make it really fast,
> too.
>
> --
> Thomas Rast
> trast@{inf,student}.ethz.ch
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