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Re: Performance issue of libtool-2.4.4
From: |
Richard Purdie |
Subject: |
Re: Performance issue of libtool-2.4.4 |
Date: |
Tue, 10 Feb 2015 10:35:52 +0000 |
On Mon, 2015-02-09 at 23:36 +0000, Richard Purdie wrote:
> On Mon, 2015-02-09 at 13:05 +0000, Richard Purdie wrote:
> > In an effort to get to the bottom of this I made a git bisection, timing
> > the performance of building xz with make -j1 using each different
> > libtool.
> >
> > The issues come down to this commit:
> >
> > http://git.savannah.gnu.org/cgit/libtool.git/commit/?id=0a42997c6032b9550a009a271552e811bfbcc430
> >
> > libtool: rewritten over funclib.sh instead of general.m4sh.
> >
> > Before that, I get a time of about 20s, after it, 39s. If I cherry-pick
> > in the fix in master mentioned above, I get 27s.
> >
> > So whilst things are better (thanks!), the above change is still causing
> > a regression in the performance somewhere else. Any ideas what else in
> > that rather large change may be causing this?
>
> To further narrow this down, of the changes in the above commit, the
> problem appears to be in the changes to the option parsing code. I've
> included the diff below which if I apply on top of the above, I get the
> speed back. I've left the func_split_short_opt/func_split_long_opt code
> in there but that is worth a tiny part of the speed, the issues are
> around the addition of the func_options call.
>
> As yet I don't know enough about the code in question to know why this
> is an issue but traces of libtool show a lot more looping in code to do
> with argument parsing and quoting.
To be more specific, if I take my "good" libtool and add:
func_options_prep ${1+"$@"}
it slows the build down by 0.5s on a 21s build. If I look at
func_options_prep and comment out the line:
func_run_hooks func_options_prep ${1+"$@"}
I get the 0.5s back.
In func_run_hooks, if I comment:
func_quote_for_eval ${1+"$@"}
func_run_hooks_result=$func_quote_for_eval_result
I get the 0.5s back. The issue is all the quoting of the various return
values through all this looping. It doesn't appear to be hitting the
printf/sed in func_quote_for_eval which would be an obvious slow path,
its just the shear number of loops run through with the commandline
arguments. The change adds a number of calls to func_run_hooks, not just
the single test case I have above and all combined, it slows things down
significantly.
So is there a way we can change things so its not calling
func_quote_for_eval all the time with all the looping that entails?
Cheers,
Richard
- Re: Performance issue of libtool-2.4.4, (continued)
- Re: Performance issue of libtool-2.4.4, Bob Friesenhahn, 2015/02/04
- Re: Performance issue of libtool-2.4.4, Robert Yang, 2015/02/04
- Re: Performance issue of libtool-2.4.4, Robert Yang, 2015/02/05
- Re: Performance issue of libtool-2.4.4, Bob Friesenhahn, 2015/02/05
- Re: Performance issue of libtool-2.4.4, Robert Yang, 2015/02/06
- Re: Performance issue of libtool-2.4.4, Bob Friesenhahn, 2015/02/06
- Re: Performance issue of libtool-2.4.4, Robert Yang, 2015/02/08
- Re: Performance issue of libtool-2.4.4, Richard Purdie, 2015/02/09
- Re: Performance issue of libtool-2.4.4, Peter Rosin, 2015/02/09
- Re: Performance issue of libtool-2.4.4, Richard Purdie, 2015/02/09
- Re: Performance issue of libtool-2.4.4,
Richard Purdie <=
- Re: Performance issue of libtool-2.4.4, Gary V. Vaughan, 2015/02/10
- Re: Performance issue of libtool-2.4.4, Richard Purdie, 2015/02/10
- Re: Performance issue of libtool-2.4.4, Robert Yang, 2015/02/10
- Re: Performance issue of libtool-2.4.4, Gary V. Vaughan, 2015/02/10
- Re: Performance issue of libtool-2.4.4, Peter Johansson, 2015/02/06
- Re: Performance issue of libtool-2.4.4, Peter Rosin, 2015/02/06
- Re: Performance issue of libtool-2.4.4, Gary V. Vaughan, 2015/02/06
- Re: Performance issue of libtool-2.4.4, Peter Rosin, 2015/02/06
- Re: Performance issue of libtool-2.4.4, Gary V. Vaughan, 2015/02/06
- Re: Performance issue of libtool-2.4.4, Tom Ghyselinck, 2015/02/06