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

[Rui Ueyama via llvm-commits]

On Fri, Oct 28, 2016 at 5:51 AM, George Rimar <grimar at accesssoftek.com>
wrote:

> >George, given that there doesn't seem to be that many uses of this
> >format right now, how about just converting this patch to implement
> >--symbol-ordering-file? That way we would be able to say that, for
> >example, _int_malloc should be at the start of the file.
> >
> >Cheers,
> >Rafael
>
> I probably would vote for implementing both options. As far I saw in
> firefox scripts
> they have option to take list of symbols, and then build a list of
> sections for
> --sections-ordering-file by themselves. Though it is looks never used
> for regular linux build.
>
> Today I was able to launch icegrind (https://glandium.org/blog/?p=1008).
> It was a bit painfull because it was not committed old patch, so had to
> apply it manually for recent code release and was not sure it will work
> because had to comment checks and so on,
> but finally was able to produce a list of sections !
>
> Current my plans for today - use that file to link libxul.so (which is
> main DSO of
> firefox) and measure the amount of page faults with/without ordering for
> start.
>

Minimizing the number of page faults is not a goal of this feature
(although it could be a measure to achieve it.) You want to measure the
start up time of the app. That's what this feature was originally designed
for.

I hope that can prove the idea of such patch and we will able to implement
> the
> --symbol-ordering-file and probably something else like ordering of
> .text/[hot/startup/*] sections etc.
>
> George.
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