Re: [PATCH v1 0/3] [RFC] Speeding up checkout (and merge, rebase, etc)

[Ben Peart <peartben@gmail.com>]

On 7/26/2018 3:40 PM, Junio C Hamano wrote:
> Duy Nguyen <pclouds@gmail.com> writes:
> 
>> I'm excited so I decided to try out anyway. This is what I've come up
>> with. Switching trees on git.git shows it could skip plenty entries,
>> so promising. It's ugly and it fails at t6020 though, there's still
>> work ahead. But I think it'll stop here.
> 
> We are extremely shallow compared to projects like the kernel and
> stuff from java land, so that is quite an interesting find.
> 

I had a few minutes so applied this patch to the latest git for windows 
and ran the p0006-read-tree-checkout.sh perf test on the git repo as 
well as a synthetic large repo.  The results look quite promising - up 
to a 28.8% savings!

I'm out of time this week but am _very_ interested in seeing if this can 
be completed successfully.

Ben


git repo results
================

Test                                                            this 
tree          gfw
---------------------------------------------------------------------------------------------------------
0006.2: read-tree br_base br_ballast (1000001) 
1.37(0.04+0.09)    1.34(0.03+0.09) -2.2%
0006.3: switch between br_base br_ballast (1000001) 
50.21(0.07+0.09)   50.22(0.03+0.09) +0.0%
0006.4: switch between br_ballast br_ballast_plus_1 (1000001) 
3.58(0.03+0.09)    4.61(0.03+0.10) +28.8%
0006.5: switch between aliases (1000001) 
3.67(0.03+0.07)    4.56(0.01+0.07) +24.3%


large synthetic repo results
============================

Test                                                            this 
tree          gfw
---------------------------------------------------------------------------------------------------------
0006.2: read-tree br_base br_ballast (1000001) 
1.33(0.04+0.04)    1.33(0.04+0.06) +0.0%
0006.3: switch between br_base br_ballast (1000001) 
48.96(0.03+0.12)   50.76(0.03+0.07) +3.7%
0006.4: switch between br_ballast br_ballast_plus_1 (1000001) 
3.64(0.01+0.09)    4.59(0.06+0.07) +26.1%
0006.5: switch between aliases (1000001) 
3.68(0.03+0.07)    4.66(0.04+0.06) +26.6%