jonasn@ttds.UUCP (Jonas Nygren) (05/18/89)
When trying out X on a DEC3100 with dxwm, DEC's window manager, I ran a small
program which drew arc's in a window, and I was astonished by the speed, or
rather the lack of speed. In a 300 by 300 window the following code was
executed (monochrome, only Xlib, after necessary initializations):
t = time(0L);
for(i = 5; i < 3000; i += 10)
XDrawArc(disp,win,gc,0,0,i,i,90*64,90*64);
XSync(disp,0);
printf("Time: %ld s.\n",time(0L) - t);
The time reported was 238 s !!! Is this fast or slow in X-reality?? I tried out
the same code on a Mac (using Mac-OS, Quickdraw etc, NOT X) and with the same
window size and the same for-loop the measured time was 32 s !!!
The DEC3100 is approx 20-25 faster than my MacPlus on integer operations which
indicates that the Mac is approx 140 (238/32 * 20) times more efficient than
the DEC3100 regarding this graphic test. Could anybody tell me what is
happening in the X-code ???
When I tried to break this test with ^C's I found out that the system no longer responded, indicating that the X-server had some abnormal priority. Is such
a behaviour normal when running X standalone on a workstation or is this
something DEC-specific ??? Is there anything I could do to alter this ???
/jonas
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Subject:
Reply-To: jonasn@ttds.UUCP (Jonas Nygren)
Organization: The Royal Inst. of Techn., Stockholmfisher@moon.dec.com (05/19/89)
Jonas Nyrgen asks about the speed of arcs on a DECstation 3100 vs a MAC. I am not a MIPS or Ultrix heavy (I'm from VMS, actually), but you need to consider that you are not really comparing apples to Apples (ahem :-) ). Seriously, the X protocol specifies arcs quite precisely, but in general, it is quite expensive to implement this spec. Have you tried comparing (width=0) lines? How about text? Etc. Burns