[gentoo-dev] Re: proxy maintainership and gentoo-x86 scm

[Paul Arthur]

On 2010-01-14, Nirbheek Chauhan <nirbheek@g.o> wrote:
> On Wed, Jan 13, 2010 at 9:24 PM, Mike Frysinger <vapier@g.o> wrote:
>> i think our current work flows also significantly impede the smooth running of
>> this.  if we had were using a dscm (git) on gentoo-x86, i feel like it'd be a
>> much smoother ride for Gentoo devs to pull from a proxy maintainer and push on
>> their behalf.
>
> In theory, yes. In practice, git is too slow to handle 30,000 files.
> Even simple operations like git add become painful even if you put the
> whole of portage on tmpfs since git does a stat() on every single file
> in the repository with every operation.
>
> Simple test: do a git init followed by git add && git commit -m
> "Initial commit" in your portage dir (.gitignore packages/ and
> distfiles/)
>
> Once this is done, you can test how it'll feel like to use a DSCM on
> portage (without history). Unless you have a really fast SSD and
> processor, you'll want to go back to the good old days of CVS with its
> network-bound latencies on just 5-6 files in the current dir.

Ouch.  I wanted to test this in a fairly bad scenario, so I gave it a
try on my old, low-spec fileserver.

aravis-root /usr/portage # time git add .
real    19m1.333s
user    0m53.230s
sys     1m9.350s

aravis-root /usr/portage # time git commit -m "Initial commit"
real    19m44.700s
user    0m23.740s
sys     0m49.320s

Then, with no changes whatsoever:
aravis-root /usr/portage # time git status
real    4m26.454s
user    0m2.090ssys     0m6.380s

Finally, a ray of hope:
aravis-root /usr/portage/app-emulation # time git add xen-tools-gdbserver/
real    0m0.978s
user    0m0.400s
sys     0m0.180s

But no:
aravis-root /usr/portage/app-emulation # time git commit -m "Commit 2"
real    3m18.502s
user    0m1.830s
sys     0m7.530s

Now, this is fairly close to a worst-case scenario, being an old
computer with a slow drive. A new computer with faster drives (in
RAID 1+0) is much more reasonable.

lasaraleen portage # time git add .
real    0m26.002s
user    0m6.256s
sys     0m6.572s

lasaraleen portage # time git commit -m "Initial commit"
real    0m27.371s
user    0m3.704s
sys     0m3.856s

lasaraleen app-emulation # time git commit -m "Commit 2"
real    0m1.374s
user    0m0.468s
sys     0m0.904s


-- 
Having to infer what Unix is solely from a copy of the GNU Manifesto is
not really an exercise you want to undertake. 
    --AdB