What use SMP?

[Baroque]

Do games see any real befit from SMP systems? What I'm asking is would it be better to have two 2.oddGHz processors or a single 3.5GHz processor?

(Lets assume for arguments sake that all of the CPU's involved were running with the same amount of L2 cache. Not realistic when you compare a Xeon to a P4, but if we assume otherwise then we'd have to talk about bus speeds and a whole load of other malarkey.)

[Super Stu]

Not many, fella. I believe Quake3 (and therefore games based on the engine?) have SMP capabilities, which gave, what, a 50% speed boost or something? I forget the benchmarks, was a long time ago.

No idea if d3/hl2 or indeed q4 supports SMP.

Off the top of my head, I know nothing else gaming wise, tho clearly Windows NTx will make some use of it, for something. The game has to specifically take advantage of it see, and barely anything does.

I did know of someone who ran 1 distributed crunching program on one cpu (that cancer one) and SETI on the other, however

[Baroque]

Thought so, like most desktop applications games tend to be single threaded. It'll take an act of AMD or Intel to change that fact, and neither of them want to cannibalise their dual processor workstation & server revenues just so the physics engine in HL2 has some clock cycle breathing room.

I've been investigating buying a PC for gaming as the laptop doesn't cut the mustard, DELL's Precision 650 workstation line is a dual Xeon rig with the option to go SCSI for the drives. Both options which I'd guess would be completely lost on todays games, they not being written to utilise SMP and not doing enough disk thrashing to feed a SCSI disk.

Never mind, I really didn't have the money anyway. ;-)

[Super Stu]

Aye, exactly. Drives these days are ultra fast (ata133 and sata150, let alone scsi) but you don't want stuff thrashing the disk(s) anyway. Makes more sense to invest in a lot of ram, which (and I keep citing this like a stuck record, but it really did make a massive difference) helped SWG no end - there's no disk access at all since I added another 512.

Get on IRC this time of night, could have said all that to you quicker

[yashiro]

No point in SMP for games under Windows.
For a gaming rig get the fastest single cpu available.

[Valken]

Thought so, like most desktop applications games tend to be single threaded.

I've read on some game dev site that a lot of games devs are spawning a second thread to handle events (game and OS events) while letting that standard win32 loop handle drawing.

Of course it's up the the OS to hand threads to different CPUs unless the program's specifically programmed for SMP so there's no guarantee that each thread will run on a different processor.

Sorry I don't have a link to back what I'm saying up... I'll search my bookmarks for the page.

Stu's right anyway... you can never have too much RAM (unless it's more than 4GB I guess but I think windows only supports 2GB anyway)

[Tom Salter]

Intel's newer compilers make use of SMP (with the Hyperthreading processors and all that) and games developers are being persuaded (slowly but surely) to use them.

like stu said, with the only SMP-compliant game engine around being Quake 3 (and I heard you sometimes get a lower framerate with /r_smp 1 than without, due to the overheads in keeping the cpu's in tandem) so there's not much point at the moment.

Best wait to see what pans out, but like Yash says, atm, just get a nice fast single cpu.