Re: Command line way to prevent unbuffered?

[Jim K. <je...@kl...>]

Jim Kleckner wrote:

> I'm using gnuplot to create PDF files most of the time.  I find that 
> the unbuffered setting to make X11 work with the mouse and pasteboard 
> vastly increases the syscall overhead for this batch operation.  Would 
> it make sense to add an argument to be able to permit buffering?  I'm 
> using cygwin so perhaps there is some set of porting options that 
> interact on this platform.


I looked at the code lower down where the "interactive" variable is set.
The most minimal change seemed to be to duplicate the isatty code as
follows:

diff -u -r1.72 plot.c
--- plot.c    25 Aug 2004 22:33:16 -0000    1.72
+++ plot.c    11 Jan 2005 05:26:21 -0000
@@ -422,7 +422,9 @@
      * Do any non-X platforms suffer from the same problem?
      * EAM - Jan 2004.
      */
-    setvbuf(stdin, (char *) NULL, _IONBF, 0);
+    if (isatty(fileno(stdin))) {
+        setvbuf(stdin, (char *) NULL, _IONBF, 0);
+    }
 #endif

My regression tests before the change (on a 3GHz P4 HT machine) used:
 940.66user 628.54system 25:19.91elapsed
and after:
  621.38user 5.32system 10:22.86elapsed

The difference is so big because I'm using gnuplot-py to drive
the plots and it uses a pipe and inline data (quite a lot of it).

Comments?  I might easily be missing something important
here.

Jim