

Firefox 8 for Windows x64: Has 64-bit browsing finally come of age? - thomas
http://www.extremetech.com/computing/90546-firefox-8-x64-has-64-bit-browsing-finally-come-of-age

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kenjackson
I'd love to hear from Mozilla how they got the 64bit version to be faster than
the 32bit version. The 64bit versions of apps tend to have to move more data,
due to the increased address size. The big advantage the 64bit versions tend
to have is more registers for apps, but for most real apps the increased
memory pressure is a bigger deal.

Looking forward to Mozilla's blog on writing high performance 64bit apps. :-)

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archangel_one
I vaguely recall seeing a Mozilla presentation while back saying that they had
gone to using 64 bits to store JS variables even on 32-bit machines - this was
faster since doubles then fit directly, but presumably on a 64-bit machine it
would get faster again.

Edit: <http://hacks.mozilla.org/2011/03/firefox4-performance/> refers to
64-bit NaN boxing and links to the article I was thinking of, but
unfortunately that seems to be broken.

~~~
danwolff
"NaN-tagging: 64 bit tagged values are used for stack slots and table slots.
Unboxed floating-point numbers (doubles) are overlayed with tagged object
references. The latter can be distinguished from numbers via the use of
special NaNs as tags. It's a remote descendant of pointer-tagging.

[The idea dates back to 2006, but I haven't disclosed it before 2008. Special
NaNs have been used to overlay pointers before. Others have used it for
tagging later on. The specific layout is of my own devising.]" [1]

[1] <http://article.gmane.org/gmane.comp.lang.lua.general/58908>

~~~
kenjackson
Interesting, but I don't think I fully understand when you'd use it. Why would
you need to couple object references with floating-point values?

~~~
danwolff
Uneducated conjecture: They're not just any floating points, they are doubles.
You need twice the capacity of one (32-bit double) in order to fake 64 bits. I
assume that this helps meet the requirements of other pieces being hacked
together.

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hristov
Linux users have been using 64 bit Firefox for years now.

~~~
beej71
64-bit Chrome, as well, for that matter.

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01Michael10
I keep reading about Firefox 7/8 and their improved memory footprints, speed,
and now a 64-bit version. Firefox 6 hasn't even been released yet and it's all
ready a let down.

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SeoxyS
1) Wait, they're up to Firefox 8 now? I thought I heard something about
Firefox 5 coming out a couple weeks ago.

2) Wait, they're still mainly 32-bit? People still use 32-bit computers? Maybe
that's my being a Mac user, but I don't think I have very many 32-bit apps
left.

~~~
eric-hu
Firefox 5 is already out. Mozilla's aiming for shorter development cycles on
each major version release to compete better with Chrome.

As a Windows/Ubuntu user, I'm under the impression that most apps I use are
still 32 bit unless stated otherwise

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antimora
great, now all my 8GB of ram will be eaten up.

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ben_straub
The largest benefit you can expect to get from compiling 64-bit is the ability
to address more memory. Performance is a bad reason, unless you need extra
floating-point precision or your problem is highly vectorized, and you just
doubled the size of all your pointers, so you'll be getting more cache misses.
I'm really interested in how they managed these downsides.

~~~
azakai
Don't forget that 64-bit has more registers. That can be significant for
performance.

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mixmastamyk
Yes on x86, it is not generally the case.

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jbk
The story is about Firefox on Windows...

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mixmastamyk
He wrote it as if it were a universal truth.

(And the downvoter can shove it.)

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dfc
As long as you don't run debian/amd64 and consider a decent flash binary from
adobe a requirement.

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NanoWar
How come I use Firefox 3.6 and there is already a version 8? Man, things go
fast...

~~~
trafficlight
Where have you been? The Firefox version scheme changes have been talked about
almost every day here for the last few months.

~~~
mixmastamyk
Doesn't seem to feel right. They could have gone with 4.1, 4.2, 4.3, etc, and
expectations would be better managed.

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rbanffy
Do you know which version is the current one for Google Chrome? Me neither.

That's the point - it works and I don't really care which version number I am
running as long as it works.

~~~
mixmastamyk
I don't use chrome much, but have a decade or two of experience with point
releases delivering significant features. Hence the dissonance.

