Mercurial and Bazaar SSH Speed

[John Arbash Meinel]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 9/29/2010 8:21 PM, Martin Pool wrote:
> Both these lists now have a policy against cross-posting, because it
> tends to degenerate into noise, but I'm letting the first post through
> for the record.
> 
> As I understand it, it turns out that the server here is very
> cpu-constrained compared to a typical modern pc.  Neither hg nor bzr
> is really tuned for that case.  Because bzr can operate pretty well
> across sftp it did much better here.
> 

I would actually guess that this is 'dumb transport' support at work.
IIRC Mercurial has an ssh mode that doesn't require hg to be installed
on the other end, but invokes stuff like 'cat' and 'ls'. (I could be
completely wrong.)

The main thing I noticed was the:

Cygwin Hg Cygwin-SSH:       7m 11s      14m 3s
Cygwin Hg Compressed-SSH:   5m 37s      5m 25s

Which leads me to believe that Hg isn't compressing content
over-the-wire which is having a dramatic effect based on bandwidth.

IIRC, the hg smart protocol un-zlibs the local content, and then bzip2's
the network stream. So I would expect compressing the ssh data wouldn't
help if you were using a smart conversation.

I would also guess that bzr has had a bit more effort spent at
dumb-transport performance.

John
=:->
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (Cygwin)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iEYEARECAAYFAkykKMkACgkQJdeBCYSNAAMhBQCfdyP8pOivhzAXVszHSIAUSkBl
zksAnjRtS6hZSbYpTFAvNP89t5aiS/ET
=Kijx
-----END PGP SIGNATURE-----