Inside AMD's Phenom Architecture

An anonymous reader writes "InformationWeek has uncovered some documentation which provides some details amid today's hype for AMD's announcement of its upcoming Phenom quad-core (previously code-named Agena). AMD's 10h architecture will be used in both the desktop Phenom and the Barcelona (Opteron) quads. The architecture supports wider floating-point units, can fully retire three long instructions per cycle, and has virtual machine optimizations. While the design is solid, Intel will still be first to market with 45nm quads (the first AMD's will be 65nm). Do you think this architecture will help AMD regain the lead in its multicore battle with Intel?"

Comments

Re:Begging the question

[tomstdenis]

In terms of market share, no. In terms of tech yes. See Opteron v. Intel P4 Xeon for example.

Tom

Re:Begging the question

[Chris Burke]

I introduce to you the Pentium D.

Re:Sorry what?

[TheThiefMaster]

My workstation is a core 2 quad, and a full debug build of our project takes 20 minutes, despite using a parallel compiler. On a single core it takes about an hour. You don't want to know how long the optimised build takes on one core.

So there are plenty of workstation uses for a quad core, but I agree that at the moment it's overkill for a home desktop.

Re:Sorry what?

[rrhal]

While I think quad-cores are important for the server rooms, I just don't see the business case for personal use. It'll just be more wasted energy. Now if you could fully shut off cores [not just gate off] when it's idle, then yeah, hey bring it on. But so long as they sit there wasting 20W per core or whatever at idle, it's just wasted power.

AMD's cool & quiet tech will shut down individual cores when you are not using them. I believe this is all new for the Barcelona. It idles down cores when you are not using them fully. It shuts off parts of cores that you aren't using (eg the FPU if you are only using integer instructions).

Re:Support?

[Mr Z]

Prevailing wisdom and personal experience suggest using "-j N+1" for N CPUs. I have a 4 CPU setup at home (dual dual-core Opterons). Here's are approximate compile times for jzIntv + SDK-1600, which altogether comprise about 80,000 lines of source:

• -j4: 6.72 seconds
• -j5: 6.55 seconds
• -j6: 6.58 seconds
• -j7: 6.59 seconds
• -j8: 6.69 seconds

Now keep in mind, everything was in cache, so disk activity didn't factor in much at all. But, for a typical disk, I imagine the difference between N+1 and N+2 to be largely a wash. N+1 seems to be the sweet spot if the build isn't competing with anything else. Larger increments might make sense if the build is competing with other tasks (large background batch jobs) or highly latent disks (NFS, etc). But for a local build on a personal workstation? N+1.

--Joe