[PATCH] D25766: [ELF] - Implemented --section-ordering-file option.

[Rui Ueyama via llvm-commits]

On Thu, Oct 20, 2016 at 1:30 PM, Sriraman Tallam <tmsriram at google.com>
wrote:

> On Thu, Oct 20, 2016 at 1:07 PM, Rui Ueyama <ruiu at google.com> wrote:
> > +tmsriram because he seems to have done something with
> > --section-ordering-file so he might have an expert's opinion about how
> much
> > it is useful/effective.
>
> http://taras.glek.net/blog/2010/04/05/linux-how-to-make-
> startup-suck-less-and-reduce-memory-usage/
>
> --section-ordering-file in gold was used to reduce firefox startup
> time IIRC.  It was/is also used by Chrome for similar purposes.


I wonder if we can see that much difference on SSDs.

>
> > On Thu, Oct 20, 2016 at 8:48 AM, George Rimar <grimar at accesssoftek.com>
> > wrote:
> >>
> >> grimar added a comment.
> >>
> >> In https://reviews.llvm.org/D25766#574420, @davide wrote:
> >>
> >> > In https://reviews.llvm.org/D25766#574368, @ruiu wrote:
> >> >
> >> > > Is this effort coordinated with Davide?
> >> >
> >> >
> >> > Yes! Thanks George for taking care of this.
> >> >  BTW, I think the hard part of this feature is trying to evaluate and
> >> > understand if it's worth it.
> >> >  You may want to do some benchmarking/write a systap/dtrace script to
> >> > collect data and feed into the linker and make sure this has some real
> >> > impact. I recommend to use bare metal for testing and not VM as the
> results
> >> > might be unreliable.
> >> >  Rui, Rafael, what do you think?
> >>
> >>
> >> After today investigations I found next more or less known ways to
> produce
> >> such file.
> >>
> >> - First is use of valgring + icegrind plugin:
> >>
> >>
> >> https://blog.mozilla.org/tglek/2010/04/07/icegrind-valgrind-plugin-for-
> optimizing-cold-startup/
> >> https://glandium.org/blog/?p=1008
> >> Method looks a bit outdated though.
> >>
> >> - Use of function_reordering_plugin from gcc google branch
> >> (https://codereview.appspot.com/5124041,
> >> https://codereview.appspot.com/4802070/).
> >>
> >> As far I understand along with job it do, it also should produce
> >> final_layout.txt file where sections should be dumped in a correct
> order,
> >> and we should be able to reuse that file for LLD needs.
> >>
> >> - facebook/hhvm
> >> (https://github.com/facebook/hhvm/tree/master/hphp/tools/hfsort) has
> tools
> >> and scrips for generating sections ordering file for gold, though
> >>
> >> I am not sure how much easy can be to reuse it for any other
> applications.
> >>
> >> I am going to check gcc way tomorrow, it seems to me as most easy
> possible
> >> path.
> >>
> >>
> >> https://reviews.llvm.org/D25766
> >>
> >>
> >>
> >
>
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