PATCH: SBU method change and bc removal.

Ag. D. Hatzimanikas a.hatzim at
Thu May 24 08:01:52 PDT 2007

On Thu, May 24, at 06:27 Dan Nicholson wrote:
> One slightly bad thing happening there is that the build commands used
> to be run in a dedicated subshell ( ). With that, any variables set
> wouldn't leak to the parent process.

Funny, I was wandering about the same thing after I went out and thinking
the implementation and I didn't knew the answer.

> Wait. That doesn't matter since make is running all commands in a their
> own dedicated shell anyway.

So, it's not possible to store in a variable the abstraction:
$end - $start
and take the total seconds of the build while we are doing the
calculations, can't we?
That's why I had to write it in the log file first.

> One other thing to think about is that we lose resolution when we just
> use whole seconds. But, that can be recovered if we use the %N
> modifier from date.

Does really matters? We are talking about nanoseconds, anyway it's not
that difficult if you would like to do that.
The difficult thing these is to win the Spurs and Duncan these days. :)

> But, the same thing could be done with time and a proper TIMEFORMAT
> variable. So, I think that the using perl instead of bc is a win.
> Using perl instead of time doesn't really gain anything, though.
> I'd originally written that, it was because we were trying to figure
> out how to use dash, which doesn't have a time builtin. But, just
> forcing bash makes things easier.

This approach is shell agnostic, doesn't depends in Bash internal variables
like time and so on, and so could be adopted by other shells which is my 
desire also.
The gain in time is negligible. I've finished one build now with this method,
and after a check it seems that it takes the same time. Actually it's
that close, see:

Patched Jhalfs : Build time is:	26 minutes and 2 seconds
Un-patched     : Build time is:	26 minutes and 35 seconds
or for	[glibc] is exactly the same.
Build time is:	16 minutes and 27 seconds
Build time is:	16 minutes and 27 seconds

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