printf is faster when piped through tee

[egb@us.ibm.com]

In past Unix systems the reason for the performance change you see was
because the stdio library detects a non-tty output
stream and buffers. Than means that instead of doing 100 system calls you
would only do one. Try putting a flushb() in after
the printf. If the performane of all three degrade to roughly equivalient
then stdio buffering is the culprit

Ed Bradford

Your Windows 2000 Arborist
T/L 589-4410; Outside: 1-919-993-4410
egb@us.ibm.com


"Jonas Jensen" <bones0_list@hotmail.com>@sources.redhat.com on 09/02/2000
10:11:08 AM

Sent by:  cygwin-owner@sources.redhat.com


To:   "Cygwin List" <cygwin@sources.redhat.com>
cc:
Subject:  printf is faster when piped through tee



Something's wrong with the performance of printf. When compiling with gcc,
printf executes much slower than with Microsoft's "cl". The funny thing is
that when I pipe those programs through "tee", they're both (equally) fast.

This is my test program:
------------------------------------------------
#include <stdio.h>
#include <stdlib.h>

void main(int argc, char** argv)
{
   register int i;
   if (argc != 2) return 1;
   i = atoi(argv[1]);
   while (i--)
      printf("%i bottles of beer on the wall...\n", i);
}
------------------------------------------------

Here are the scores of 1000 loops through this program, in seconds,
measured
with the "time" keyword in bash.

cl: 0.561
gcc: 10.055
gcc/tee: 0.861
cl/tee 0.861

It appears that there's a way to print faster, because "cat" has no
problem,
while "ls" and others suffer badly from it.
Can anyone explain/fix this?

I'm using Win2k, Cygwin 1.1.4.

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