gutfreund%umass-cs%CSNet-Relay@sri-unix.UUCP (12/18/83)
From: Steven Gutfreund <gutfreund%umass-cs@CSNet-Relay> I tend to back your conclusions on the performance of non-demand paged systems versus demand paged. I worked for 4 years at DEC, first in PDP-11 operating system design (RSTS/e) then in DEC Corporate Research on Ethernet and other local network operating system designs. Now I am at UMASS working on a Phd and on the Symbolics 3600. While I cannot make a good comparision on such (important!) things as the speed of the window system, and the speed of Lisp Compiles, I can compare equivelent file oriented operations (copy's, deletes, sending over the net, etc.) I do find the Symbolics to be slower than a stand-alone PDP-11/70 running RSTS. (also add in editor functions like searching). I will not state that this is solely do to demand paging, but my inclination runs that way. However one possible alternate explanation is that the FSedit, Dired, and Zmacs code is not poured over and optimized the way this system code is in the DEC operating systems groups. If this is indeed the correct interpretation, then it only indicates the different philosophies of these two development groups. DECies are into optimizing system intricacies, and the LispMachine people look at providing a Mobies of functions and and widgets (Zmail, ZetaLisp and Zmacs are have just about every wish list item possible - DECies like their systems lean). The reason I tend to point my finger at demand paging is that when a file search utility was written for VMS that tried to do smart (non-demand- paged) things in its search -- it was about 4 times faster than previous search routines. Conclusion: It probably is a mixture of these things that make the Lispmachines (and SUNS which we have here also) slower for mundane operations. Question: SO What do you care? When I think back to when I had to use those systems, the quality of the user interface was so poor compared to what I have on the SUN's and LispMachines, that I could care less about how fast it does string searches. - Steve Gutfreund Gutfreund.umass@csnet-relay