Re: Performance regression (binutils and gold)

[Martin Jansa <martin.jansa@gmail.com>]

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On Sun, Apr 12, 2015 at 09:45:31AM +0100, Richard Purdie wrote:
> To allow us to upgrade to the latest binutils we ended up enabling
> building of gold. Unfortunately this is clearly visible on our
> performance benchmarks, it leads to a 3-4 minute speed loss in overall
> build time :(.
> 
> Locally, benchmarks for building binutils-cross show:
> 
> Just ld:
> 
> 95.87user 48.36system 1:05.66elapsed 219%CPU (0avgtext+0avgdata
> 162480maxresident)k
> 0inputs+1030184outputs (0major+7753895minor)pagefaults 0swaps
> 
> with gold:
> 
> 366.22user 67.25system 1:14.29elapsed 583%CPU (0avgtext+0avgdata
> 435488maxresident)k
> 248inputs+1205792outputs (1major+12572236minor)pagefaults 0swaps
> richard@dax:/media/build1/poky/build2$ 
> 
> So whilst it only takes 10 seconds longer overall for me on what is a
> pretty powerful machine, you can see a huge increase in user time and
> CPU usage. I believe that on our slower quad core performance benchmark
> machine, this equates to a few minutes.
> 
> The question is therefore, do we have a better way to fix things? Is
> this performance drop acceptable?

It's acceptable for me, I think most people with slower machines (with
less ram) are already using ls-is-gold, so it won't make any difference
for them.

Regards,
-- 
Martin 'JaMa' Jansa     jabber: Martin.Jansa@gmail.com

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