From: Jeff King <peff@peff.net>
To: Dan Shumow <danshu@microsoft.com>
Cc: Junio C Hamano <gitster@pobox.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Git Mailing List <git@vger.kernel.org>,
Marc Stevens <marc.stevens@cwi.nl>
Subject: Re: [PATCH] Put sha1dc on a diet
Date: Mon, 13 Mar 2017 11:13:22 -0400 [thread overview]
Message-ID: <20170313151322.ouryghyb5orkpk5g@sigill.intra.peff.net> (raw)
In-Reply-To: <CY1PR0301MB2107112BCC2DECD215E70549C42A0@CY1PR0301MB2107.namprd03.prod.outlook.com>
On Sat, Mar 04, 2017 at 01:07:16AM +0000, Dan Shumow wrote:
> You are very welcome. Thank you for the warm welcome. As it turns
> out, Marc and I are working on the simplifications / removal of c99
> and performance upstream in our GitHub repo. I am happy to help for
> any GitHub specific customizations that are needed as well. But for
> now, lets see if we can get you everything you want upstream -- I
> think that's the most simple.
I've been watching the repo at:
https://github.com/cr-marcstevens/sha1collisiondetection
The work on the feature/performance branch seems to be producing good
results. The best timings I got show sha1dc (with checks enabled) at
1.75x block-sha1, which is pretty good. That was using your
ad744c8b7a841d2afcb2d4c04f8952d9005501be.
Curiously, the performance gets worse after that. Even more curious, the
bad performance bisects to a merge, and it performs worse than either
side of the merge.
Try this:
# mine is a 1.2GB linux packfile, but anything big should do
file=/some/large/file
# the merge with the funny behavior
merge=55d1db0980501e582f6cd103a04f493995b1df78
for i in $merge^ $merge^2 $merge; do
git checkout $i &&
rm -f bin/* &&
make &&
time bin/sha1dcsum $file
done
I get:
[$merge^, the feature/performance branch before the merge]
real 0m3.391s
user 0m3.304s
sys 0m0.084s
[$merge^2, the master branch before the merge]
real 0m5.272s
user 0m5.164s
sys 0m0.096s
[$merge, the merge of the two]
real 0m7.038s
user 0m6.924s
sys 0m0.104s
So that's odd. Looking at the diff, I don't see anything that obviously
jumps out as a mis-merge.
Feel free to tell me "stop looking at that branch; it's a work in
progress". But I think the results from $merge^ (ad744c8b7) are getting
good enough to consider moving forward with integrating it into git.
-Peff
next prev parent reply other threads:[~2017-03-13 15:13 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-01 0:30 [PATCH] Put sha1dc on a diet Linus Torvalds
2017-03-01 18:42 ` Junio C Hamano
2017-03-01 18:49 ` Linus Torvalds
2017-03-01 19:41 ` Junio C Hamano
2017-03-01 21:56 ` Johannes Schindelin
2017-03-01 22:05 ` Junio C Hamano
2017-03-01 22:16 ` Linus Torvalds
2017-03-01 22:51 ` Johannes Schindelin
2017-03-01 23:05 ` Linus Torvalds
2017-03-01 23:19 ` Jeff King
2017-03-02 6:10 ` Duy Nguyen
2017-03-02 14:45 ` Johannes Schindelin
2017-03-02 16:35 ` Linus Torvalds
2017-03-02 18:37 ` Jeff Hostetler
2017-03-02 19:04 ` Linus Torvalds
2017-03-02 14:39 ` Johannes Schindelin
2017-03-02 14:37 ` Johannes Schindelin
2017-03-01 19:53 ` Jeff King
[not found] ` <CA+55aFwf3sxKW+dGTMjNAeHMOf=rvctEQohm+rbhEb=e3KLpHw@mail.gmail.com>
2017-03-01 20:34 ` Jeff King
[not found] ` <CA+55aFwr1jncrk-cekn0Y8rs_S+zs7RrgQ-Jb-ZbgCvmVrHT_A@mail.gmail.com>
2017-03-01 23:13 ` Jeff King
2017-03-01 23:38 ` Linus Torvalds
2017-03-02 1:31 ` Dan Shumow
2017-03-02 4:38 ` Junio C Hamano
2017-03-04 1:07 ` Dan Shumow
2017-03-13 15:13 ` Jeff King [this message]
[not found] ` <CY1PR0301MB2107B3C5131D5DC7F91A0147C4250@CY1PR0301MB2107.namprd03.prod.outlook.com>
[not found] ` <CY1PR0301MB2107876B6E47FBCF03AB1EA1C4250@CY1PR0301MB2107.namprd03.prod.outlook.com>
2017-03-13 19:48 ` Jeff King
2017-03-13 20:12 ` Marc Stevens
2017-03-13 20:20 ` Linus Torvalds
2017-03-13 20:47 ` Marc Stevens
2017-03-13 21:00 ` Jeff King
2017-03-13 21:15 ` Marc Stevens
2017-03-16 18:22 ` Marc Stevens
2017-03-16 22:06 ` Jeff King
2017-03-16 22:07 ` Dan Shumow
2017-03-01 19:07 ` Jeff King
2017-03-01 19:10 ` Linus Torvalds
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