Thanks everyone for the inputs. This week I'm going to be going back
through this thread, summarizing what's been shared here, and making a
recommendation from the Product team based on this data.
So, if you've been thinking about adding more here or otherwise
contributing to this discussion, please do so ASAP so that your inputs
can help inform our planning.
Thanks,
- A
Asa Dotzler wrote:
> Firefox 64-bit for Windows 7
>
> We've been making 64-bit builds of Firefox for Windows for some time now
> but they're not "official" so they don't receive the full development,
> testing, or release support that our 32-bit Windows build gets. They're
> "unofficial" as it were.
>
> Mozilla is evaluating the pros and cons of maintaining and shipping an
> official 64-bit version and so I'm reaching out to you all for further*
> input on the subject.
>
> Here's what I've gathered so far. If you can add to this or offer
> corrections, that'd be really helpful.
>
> Advantages:
> � With more registers, Firefox users on a 64-bit build could see fewer
> out of memory crashes (actually, out-of-virtual-address-space crashes.)
> This advantage could be somewhat mooted if we chase stability wins
> elsewhere.
> � Performance could be better. Compute-intensive things that fit
> entirely in cache might get faster. Performance could be improved with
> other efforts, though.
> � Better security. The address space layout can be randomized far more
> effectively when you have 2^64 address space to work with.
>
>
> Disadvantages:*
> � 64-bit Firefox will, in most cases, use more more memory than 32-bit
> Firefox. This could be mitigated by improved memory usage across all
> builds.
> � Our 32-bit JITs are a bit better than the 64-bit ones. This could be
> mitigated by putting more effort into optimizing the 64-bit jits.
> � User confusion about which Firefox build to use. This could be
> mitigated with a stub installer or defaulting to 32-bit unless users
> explicitly went seeking out 64-bit Firefox for Windows builds.
> � User confusion about what plug-ins and add-ons work with 64-bit
> Firefox. This might take shared work from Mozilla and plug-in vendors.
> � Maintaining another build/port means more build/test/qa infrastructure
> and effort. I'm not sure how this could be mitigated. We have already
> put some of the build and test infrastructure in place.
> � Few NPAPI plug-ins are available in 64-bit and Windows offers no
> solution for "universal binaries" so we can't easily mitigate this the
> way we do with the 32-64 Mac binary. This could be mitigated if
> Mozilla's official support for a 64-bit Firefox on Windows 7 encouraged
> plug-in vendors to increase their efforts around 64-bit. This could also
> be mitigated by building a version that could fall-back to 32 bit
> plug-ins. That's a lot of work though and a resource conflict with E10S.
>
>
> Additional info:
> � Flash, Java, and Silverlight all have 64-bit Windows NPAPI plug-ins,
> though at differing levels of completeness I believe.
> � About half of win7 users are on 64-bit versions. That may not sound
> like much, but it's about 2X our Mac and Linux users combined.
> � We don't have comparative performance data between 32-bit and 64-bit
> Firefox on the same hardware. I think we need that.
> � Competitively, IE9 doesn't ship an official 64-bit build and the
> unofficial one doesn't have a modern JS** implementation. Chrome also
> does not support 64-bit on Windows*** or Mac.
>
> So, the three potential wins are stability, performance, and security.
> The downsides are user confusion, memory usage, plug-in availability,
> and resource costs.
>
> Does this paint a fair picture? What am I wrong about or missing?
>
> - A
>
>
> *
>
http://weblogs.mozillazine.org/asa/archives/2011/07/questions_about_64bi.html
>
> **
http://zd.net/p7hObC
> ***
http://code.google.com/p/chromium/issues/detail?id=8606