Re: [gentoo-sparc] 64-bit gentoo-sparc, how to make it happen?

[Etaoin Shrdlu]

On Sunday 25 June 2006 19:02, 张韡武 wrote:

> Thank you for the answer. Just another smaller question: from pruely a
> user's view (who simply wish to use it, rather then from developer
> view who might gain knowledge and fun doing it), is it worthy to try
> it (64bit sparc)?
>
> The original idea is the system as a print server is too slow (capable
> of doing fast dithering for the inkjet printer, but not fast enough to
> do real-time even-tone dithering to server the printer, usually cause
> printer to wait for server), a rough gain of 20% to 30% CPU power, by
> my guessing of observing top(1), should be enough for the printer.
> Dithering is always a CPU intensive job and we do a lot of printing.
>
> I observed kernel is taking only a very small percentage of CPU usage,
> if I try hours to get 64-bit kernel running but only obtain 5% speed
> gain, that may not be worth. Or should I try Solaris 10? Should
> Solaris provide better performance in this very case? (how much
> performance gain might happen? 10%? 20%?) I don't need a very close
> estimation, just if someone can give me a very rough estimation is
> very helpful, for I am not techincally able to do the decision:)
>
> If switch to Solaris for performance (no offensive, I am a 5 year's
> hardcore Linux user), generally speaking, is Solaris very compatible
> with PCI cards like NEC USB controller, Promise IDE controller and
> ethernet cards?

Well, I'm not a sparc dev so probably I cannot give you the most accurate 
answer you could get; moreover, I cannot speak about solaris since I 
don't know it. Anyway...
>From what I've read, the main reason gentoo stays 64 bit kernel/32 bit
userland is that switching to a full 64 bit system (perhaps with 
multilib) will not be a considerable improvement, but rather just a 
waste of memory. This is different from what happens in the x86 world, 
where being 64-bit means getting a lot of benefits (like, for example, 
many more cpu registers). In the sparc world, for an userland app "being 
64-bit" means, basically, "wasting more memory" (due to larger 
executables binaries). In short, I think that (from the pure user's view 
you were talking about), it's not worth trying.
However, I believe that a (highly experimental) userland 64-bit profile 
exists (but of course don't expect that to work flawlessly or to be 
usable in a production environment).
Read this thread on the forums, which explains all:

http://forums.gentoo.org/viewtopic-t-442194.html

btw, AFAIK solaris uses a similar 64bit-kernel/32bit-userland approach 
(or, at least, *most* of the userland is 32bit).

Hope this helps (and please somebody correct me if what I said is wrong).

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