Re: cvsup

[Vincent Stemen <vs1@xxxxxxx>]

On 2008-01-18, Bill Hacker <wbh@conducive.org> wrote:
> Vincent Stemen wrote:
>
> *snip*
>
>> 
>> Unless I am overlooking something obvious,
>
> It is not likely so many projects would be using cvsup for as long as 
> they have if the rsync advantage was that great, or that simple [1].
>
> Have you:
>
> A) compared the loads and bandwidth as well as the time on BOTH end 
> machines - host as well as client?

No.  Only client side.


> B) tested for the 'more common' case where cvsup/csup are applied to 
> rather more sparse pulls of just a fraction of older, larger 
> repositories (older *BSD's) - and by more users simultaneously?
>
> Unless I am wrong, cvsup/csup places more of the load of determining 
> what to pull on the client, less on the source server.
>
> > I think I am going to stick
>> with updating our repository via rsync :-).
>> 
>> 
>
> It may be the right answer for now, and for what you are doing.
>
> It may be less so for general end-user use - or even your own if/as/when 
> mirror hosts are under heavier load.
>
> Most older mirror hosts throttle each connection as well as limit the 
> maximum number permitted simultaneously. The one you are using presently 
> seems not to do so.
>
> The key is to include measurement of host and bandwidth as well as 
> client.  TANSTAAFL.
>
>
> Bill
>
> [1][ subversion, mercurial, et al alternatives are a different type of 
> issue.

Clearly more testing needs to be done.  I only posted the results of my initial
tests comparing cvsup to rsync because I keep finding postings and
documentation about how cvsup is faster than rsync with cvs repositories, yet
my initial tests were so dramatically in contrast.

Most of the cvsup vs rsync performance claims I have found seem to be based on
architecture and/or protocol but I have yet to find any significant real world
test results supporting them.

The only actual comparison test results I have found so far, other than what
I posted, are from Justin Sherril, who posted some test results on the
dragonfly.users mailing list back in April of 2007 indicating cvsup was
moderately faster at the time.  So far as I can tell, he only tested the client
side as well.  He also added,

    Caveats: I didn't test CPU usage.  Also, this was with rsync 2.x - there's
    a new version 3 on the way that is supposed to have improvements.

If there is interest, I will try to make time to do more client side comparison
tests (for different aged repositories, to different servers, etc) and post the
results.  I don't have time to setup for doing server side testing, but if my
results continue to contradict the cvsup vs rsync claims, then perhaps it will
spark interest in others in doing additional comparison testing for both client
and server.

Also, if nobody has written one or is working on one, I am considering writing
a script to provide basic cvsup like features/functionality for repository
updates via rsync.

Is there interest in me posting it here if I write it?  It would be something
handy to have available on the DragonFly download site.