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To:	rc@hawkwind.utcs.toronto.edu
Subject: Re: builtins and more 
Date:	Wed, 22 Sep 1993 12:49:42 -0400
From:	Alan Watson <alan@oldp.astro.wisc.edu>
X-Mts: smtp

Malte writes:
> About the performance of a backquote-style read:
> I have checked the difference between
>     while(){ echo `{ /bin/echo true }}
> and
>     while(){ echo `{ echo true }}
> on my favourite machine. It seems to me that the exec(2) is by far more
> expensive than the fork(2). So the backquote solution may be a good compromise
> between clearity and performance.

On DEC MIPS and Alpha machines, fork and exec are both take
approximately the same time.  Read is a perfomance hack, and a worse
one than builtin echo; it isn't as elegant as `line, but it is fast
enough to be much more useful.  I would much rather see fork and exec
speeded up by a few orders of magnitude, but we all know that isn't
going to happen.