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Conference bulova::decw_jan-89_to_nov-90

Title:	DECWINDOWS 26-JAN-89 to 29-NOV-90
Notice:	See 1639.0 for VMS V5.3 kit; 2043.0 for 5.4 IFT kit
Moderator:	STAR::VATNE

Created:	Mon Oct 30 1989
Last Modified:	Mon Dec 31 1990
Last Successful Update:	Fri Jun 06 1997
Number of topics:	3726
Total number of notes:	19516

1094.0. "server char transmit decnet packet?" by CAADC::PMWVESTUTO () Tue Jul 11 1989 17:50

    
    
    My customer has some concerns about inherent performance problems
    with the client/server model in DECwindows.  He heard that whenever
    you type a character on the server side, it sends a packet to the client,
    so it can echo back the character.
    
    Is this true? Is there some specific documents I can read in regards
    to this area??
    
    If it is somewhat true, doesn't it hurt performance? It sounds like it
    should.
    
    
    Thanks!
    
    Viki

T.R	Title	User	Personal Name	Date	Lines
1094.1	It gets worse	FLUME::dike		`Tue Jul 11 1989 18:04`	13
	Not only that, if you sit down and figure out everywhere that character goes, you get quite a trip. It starts in the keyboard driver, goes to the server, through the kernel network code, over the net to another machine, through that machine's network code, out to xterm, xterm extracts that character from the X event and sends it to shell under it via another path through the kernel. Then the second half of the trip, which is a reversed mirror image of the first half, begins, to cause the character to echo. That is was happens on Ultrix. On VMS, it is probably somewhat different. It seems somewhat incredible that under most circumstances, character echoing appears instantaneous. Jeff
1094.2	And windows is NOT the greater part of it!	VINO::WITHROW	Robert Withrow	`Tue Jul 11 1989 18:46`	7
	> Not only that, if you sit down and figure out everywhere that character goes, > you get quite a trip.... And if you really compare apples-vs-apples (i.e. you are talking about running an application remotely, say via a HOSTed terminal) there isn't all that much additional overhead for a windows -vs- non-windows application.
1094.3		VWSENG::KLEINSORGE	Toys 'R' Us	`Tue Jul 11 1989 21:25`	79
	+-------------+ ! LK201 ! User types key +-------------+ ! ! +-------------+ ! Port driver ! Device driver gets it +-------------+ ! ! +-------------+ ! IKDRIVER ! Pass to the DWS KB +-------------+ ! ! +-------------+ ! INDRIVER ! Pass to the common class drvr +-------------+ ! ! +-------------+ ! PACKET ! Insert into a packet and WAKE +-------------+ the server ! ! +-------------+ Context of server process. ! SERVER ! Server dequeue and processing. +-------------+ ! ! DECnet, local memory, TCP/IP, LAT, etc. ! +-------------+ ! DECTERM ! DECterm gets it! Context Swicth! +-------------+ ! ! QIO ! +-------------+ ! PTY ! PTY gets QIO, does PUTNXT +-------------+ to get rid of it. ! PTY PORT ! +-------------+ ! ! +-------------+ ! TTDRIVER ! VMS class driver gets it +-------------+ ! +-----------OPTIONAL-------------+ ! +-------------+ The traditional EMACS case, user ! USER ! doing echo instead of TTDRIVER. +-------------+ Context Switch! ! ! QIO ! +-------------+ ! TTDRIVER ! VMS class driver gets it (again) +-------------+ ! +-----------OPTIONAL-------------+ ! QIO ! +-------------+ ! DECterm ! DECterm gets it back! +-------------+ ! ! Decnet, local memory, etc... ! +-------------+ Server gets draw text command ! SERVER ! and finally draws it. Context +-------------+ Switch All done. Simple eh? Of course this is the terminal path, and not the user application path.