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Re: [Sketch] Don't checksum reliable transmissions

From: Philipp Marek <philipp_at_marek.priv.at>
Date: Sun, 2 May 2010 17:56:19 +0200 (CEST)

Hello Stefan!

> The idea is the following: ra_local (and possibly others)
> are "reliable" in that they won't corrupt transmission.
> For now, this implies that we don't need to checksum
> the data again. There might be more shortcuts that
> can be taken in the future.
...
> With all other patches applied, this saves 15% runtime
> in 'svn export file://'. However, rev'ing svn_delta_editor_t
> seems only be feasible in context of 'editor v2'.
I understand your point, and 15% sound very interesting.

But I'd like to note that even for local operations it's a nice feature to avoid data
corruption via software bugs (off-by-one and similar), and over LAN it's nice to have,
too (eg. because of bugs in switches and routers, see eg.
http://www.cs.pitt.edu/~kyoungsoo/cs2520/papers/CRC_TCP_Checksum.pdf).

As the WAN (Internet) uses the same protocols as a LAN (TCP, IP) following that argument
would mean that the checksum is informational only, and doesn't need to be checked.

So I'd propose that this would be configurable for the paranoid people (like me, maybe ;-).

Regards,

Phil

-- 
Versioning your /etc, /home or even your whole installation?
             Try fsvs (fsvs.tigris.org)!
Received on 2010-05-02 17:56:52 CEST

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