# [RFC/PATCH] rename: warn user when we have turned off rename detection 4 messages from 2008-03-01 to 2008-03-01. Participants: Jeff King, Junio C Hamano. Thread: https://gitlist.dev/t/12400 ## Jeff King, 2008-03-01 06:14 Subject: [RFC/PATCH] rename: warn user when we have turned off rename detection Message-ID: <20080301061431.GA27301@coredump.intra.peff.net> URL: https://gitlist.dev/e/20080301061431.GA27301%40coredump.intra.peff.net ``` Signed-off-by: Jeff King --- This was another patch from late in the freeze period. It was in response to a user getting confused about why rename detection wasn't happening in a large merge. Is it appropriate to print this for every rename we try? Or should it just be for merges? Perhaps we should also bump the default limit from 100, which I think was just arbitrarily chosen. I posted some numbers in: http://mid.gmane.org/20080211113516.GB6344@coredump.intra.peff.net which imply that 200-400 is probably a more reasonable value. Thoughts? diffcore-rename.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/diffcore-rename.c b/diffcore-rename.c index 3d37725..31941bc 100644 --- a/diffcore-rename.c +++ b/diffcore-rename.c @@ -468,10 +468,11 @@ void diffcore_rename(struct diff_options *options) */ if (rename_limit <= 0 || rename_limit > 32767) rename_limit = 32767; - if (num_create > rename_limit && num_src > rename_limit) - goto cleanup; - if (num_create * num_src > rename_limit * rename_limit) + if ((num_create > rename_limit && num_src > rename_limit) || + (num_create * num_src > rename_limit * rename_limit)) { + warning("too many files, skipping inexact rename detection"); goto cleanup; + } mx = xmalloc(sizeof(*mx) * num_create * num_src); for (dst_cnt = i = 0; i < rename_dst_nr; i++) { -- 1.5.4.3.422.g55194 ``` ## Junio C Hamano, 2008-03-01 07:35 Subject: Re: [RFC/PATCH] rename: warn user when we have turned off rename detection Message-ID: <7vtzjq6gnv.fsf@gitster.siamese.dyndns.org> URL: https://gitlist.dev/e/7vtzjq6gnv.fsf%40gitster.siamese.dyndns.org In-Reply-To: <20080301061431.GA27301@coredump.intra.peff.net> ``` Jeff King writes: > Signed-off-by: Jeff King > --- > This was another patch from late in the freeze period. It was in > response to a user getting confused about why rename detection wasn't > happening in a large merge. Is it appropriate to print this for every > rename we try? Or should it just be for merges? > > Perhaps we should also bump the default limit from 100, which I think > was just arbitrarily chosen. > ... > + if ((num_create > rename_limit && num_src > rename_limit) || > + (num_create * num_src > rename_limit * rename_limit)) { > + warning("too many files, skipping inexact rename detection"); > goto cleanup; > + } > > mx = xmalloc(sizeof(*mx) * num_create * num_src); > for (dst_cnt = i = 0; i < rename_dst_nr; i++) { This reminds me of the 6d24ad9 (Optimize rename detection for a huge diff) topic that reduces the above allocation greatly. Some benching with the patch may prove useful to establish much higher limits, I suspect. ``` ## Jeff King, 2008-03-01 08:18 Subject: Re: [RFC/PATCH] rename: warn user when we have turned off rename detection Message-ID: <20080301081832.GB31855@coredump.intra.peff.net> URL: https://gitlist.dev/e/20080301081832.GB31855%40coredump.intra.peff.net In-Reply-To: <7vtzjq6gnv.fsf@gitster.siamese.dyndns.org> ``` On Fri, Feb 29, 2008 at 11:35:00PM -0800, Junio C Hamano wrote: > > + if ((num_create > rename_limit && num_src > rename_limit) || > > + (num_create * num_src > rename_limit * rename_limit)) { > > + warning("too many files, skipping inexact rename detection"); > > goto cleanup; > > + } > > > > mx = xmalloc(sizeof(*mx) * num_create * num_src); > > for (dst_cnt = i = 0; i < rename_dst_nr; i++) { > > This reminds me of the 6d24ad9 (Optimize rename detection for a huge diff) > topic that reduces the above allocation greatly. Some benching with the > patch may prove useful to establish much higher limits, I suspect. Actually, my timings are about the same. While the patch you mentioned is nice for reducing the memory consumption, we still have an O(n^2) loop. -Peff ``` ## Junio C Hamano, 2008-03-01 09:30 Subject: Re: [RFC/PATCH] rename: warn user when we have turned off rename detection Message-ID: <7vd4qe4wq7.fsf@gitster.siamese.dyndns.org> URL: https://gitlist.dev/e/7vd4qe4wq7.fsf%40gitster.siamese.dyndns.org In-Reply-To: <20080301081832.GB31855@coredump.intra.peff.net> ``` Jeff King writes: >> This reminds me of the 6d24ad9 (Optimize rename detection for a huge diff) >> topic that reduces the above allocation greatly. Some benching with the >> patch may prove useful to establish much higher limits, I suspect. > > Actually, my timings are about the same. While the patch you mentioned > is nice for reducing the memory consumption, we still have an O(n^2) > loop. Yeah, that one was not about the time but about the space, so it is expected. ```