From:	SMTP%"wing@tgv.com" 21-APR-1994 11:10:11.88
To:	EVERHART
CC:	
Subj:	Re: LATACP's WSEXTENT - performance impact?

From: wing@tgv.com (Dan Wing)
X-Newsgroups: comp.os.vms
Subject: Re: LATACP's WSEXTENT - performance impact?
Date: 20 Apr 1994 06:03:07 GMT
Organization: TGV, Incorporated
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In article <2p1u9s$n8@search01.news.aol.com>, finarfin@aol.com (Finarfin) writes:
>DECps is telling me that LATACP has a high pagefault rate and could use
>a larger WSEXTENT.  This prompts me to ask whether a hight pagefault
>rate for LATACP could have any impact on LAT performance, such as
>causing an unusually high number of LAT retransmits and/or duplicates
>received, or any other significant performance impact.

Absolutely not.  LATACP isn't used for incoming LAT connections -- to prove
it to yourself, kill it.  LATACP is the process that collects LAT 
advertisements from other nodes to allow you to do a SET HOST/LAT command.
LATACP first appeared with LATmaster (LAT V5.2) which appeared in VMS V5.5 and 
beyond, and (if you chose to install it) in VMS V5.4-x.

High numbers (over DEC's 1/1000 rule) of Retransmits or Duplicates Received
are usually indicative of a poor network -- too many bridges, or slow bridges,
or too much traffic on the network (too many collisions) -- which are causing
or otherwise contributing to causing LAT's 1 second wait-for-an-ACK timer to 
fire.

My guess as to why LATACP might be faulting heavily is you may have:

  o a lot of LAT service advertisements (like from a lot of LAT hosts, or 
    from terminal servers advertising their services)
  o your LAT "advertisement" timer (whatever it is called) set too low, 
    causing too much information to be sent all over the network
  o a lot of users using SET HOST/LAT from your system, causing stuff that
    was paged out of LATACP's working set to get paged back in (which would
    happen for either of the two situations above)

I don't know how you'd go about increasing LATACP's working set except
throught the obvious modifications to PQL_MWSEXTENT and/or PQL_DWSEXTENT; I'm
sure the LAT$STARTUP.COM file contains some references to magic logical names
that control the working set size, though.

-Dan Wing, wing@tgv.com