Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Message-ID: <40F3BFC4.9060000@alexisgallagher.com>
Date: Tue, 13 Jul 2004 11:56:04 +0100
From: Alexis Gallagher <alexis AT alexisgallagher DOT com>
Reply-To: alexis AT alexisgallagher DOT com
User-Agent: Mozilla Thunderbird 0.7 (Windows/20040616)
MIME-Version: 1.0
To: cygwin AT cygwin DOT com
Subject: Re: rsync very slow, but not a network issue
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit

Hello all,

Thanks for the help so far, on this issue with the mysterious
non-network based rsync slowdown. To recap...

Brian Dessent wrote:
> Reini Urban wrote:
>> Alexis Gallagher wrote:
>>> When the file is alredy there, rsync reports a speedup of about 
>>> 70. (When the file is not already there, the speed up is 1, of 
>>> course.) I am running rsync over ssh with pre-generated keys 
>>> installed in my .ssh directories.
>> 
>> This is a binary MP3. rsync (as diff) is not good in checking 
>> binary diffs. Please try it with a typical text file, where the 
>> patch is smaller than the source.
> 
> 
> That is not correct at all, and rsync would be much less useful if it
>  were true.  rsync works with arbitrary binary data just as well as 
> it does with text.

In any event I checked Reini's theory using a 5 MB text file that
consists only of x's and newlines. So unlike an MP3, this file is
non-binary and extremely compressible. And what I observed was as follows:

   scp: 348800 bytes/sec
   rsync (file not there): 303075 bytes/sec, with speedup of 1
   rsync (file already there): 733 bytes/sec, with speedup of 70

This is pretty much exactly the same problem as I was having with the
MP3 file. And I'm still quite puzzled.

Cheers,
Alexis


--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/