Path: utzoo!attcan!uunet!lll-winken!lll-lcc!pyramid!vsi1!lmb
From: lmb@vsi1.UUCP (Larry Blair)
Newsgroups: comp.mail.uucp
Subject: Re: Send vs receive times
Message-ID: <682@vsi1.UUCP>
Date: 16 Jun 88 01:21:48 GMT
References: <92@carpet.WLK.COM> <7040@elroy.Jpl.Nasa.Gov>
Reply-To: lmb@vsi1.UUCP (Larry Blair)
Distribution: na
Organization: VICOM Systems Inc., San Jose, CA
Lines: 27

In article <7040@elroy.Jpl.Nasa.Gov> stevo@jane.jpl.nasa.gov (Steve Groom) writes:
|In article <92@carpet.WLK.COM> bill@carpet.WLK.COM (Bill Kennedy) writes:
|>I have noticed that my systems send much faster than they receive,
|>i.e. 210 bytes/sec sending, 176 bytes/sec receiving from the other
|>site.  Anyone else notice this?  Any thoughts?
|
|Simple.  Reads on existing files are almost always faster than writes
|to new files.  The reason is that on the reads, you don't have the
|additional file system overhead of allocating disk blocks to write to.
|
|This is also why file system dumps can be made to go so much faster than
|restores.  On dumps, you're just reading the data.  On restores, you've
|doing a lot of allocating of disk blocks to do too.

Relative I/O speeds not withstanding, the reason for the difference is
the way in which uucp generates the SYSLOG data.  For received data, it's
from the start of the transmission until the CY is sent out.  For sent
data, it's from the start of the transmission until the last block is sent,
not when the CY is received.  This disparity becomes even more obvious
when a buffering modem, such as the Trailblazer, is used.

Now that I've stated that, I'm sure someone will tell me I'm wrong!
-- 
*   *   O     Larry Blair
  *   *   O   VICOM Systems Inc.     sun!pyramid----\
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  *   *   O   San Jose, CA  95134    ucbvax!tolerant/
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