Subject: Berkeley v Tenex mailbox formats for the INBOX

From: Mike Brudenell <[email-masked]>
Date: Thu, 9 Mar 1995 12:14:02 +0000 (GMT)

Hi!

I'be been doing some simplistic tests on resource usage comparing 
Berkeley and Tenex formats for INBOX access (on Silicon Graphics machines 
running IRIX 5.2)

>From memory I seem to recall that the Tenex format is generally "better" 
in that messages stored in this format are a fixed size, whereas 
Berkeley's can change size as they are read, replied to, etc.

I *presumed* that this would lead to savings in memory usage if Clever 
Things were being done to take advantage of this consistency in size.

So I doing some tests using Pine first with the mboxdriver (which uses
Berkeley format) and then the Tenex driver.  I performed these first on 
an empty INBOX, then on one with 78 messages totalling around 350Kb.

When Pine had finished opening the INBOX I used a "ps -elf" to check the 
total size of the process (the SZ value) and its resident set size (the 
RSS value - pages actually in memory).

For the non-empty INBOX at that early point (straight after the INBOX had
finished opening) the Tenex version was using *more* resident memory than
the mboxdriver/Berkeley coutnerpart (327 pages v 299 pages, where 1 page =
4Kb)

Could someone confirm whether or not there *are* advantages to using 
Tenex format, and if so what they tend to be (memory, disk I/O, CPU usage, 
etc)?

(I realise that the test I did were very simplistic and may well be giving
misleading results, but I'd hoped that they'd give a general indication of
memory usage.)

With thanks,

Mike Brudenell                                               <[email-masked]>
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