Web Hosting Talk : Other Forums : Web Hosting Lounge : What's PCI-e?

[BigBison]

Seems like every time I look at buying a new system, there's another PCI variant. Would somebody mind giving me a brief rundown on what makes this one different?

I've read the marketing blurb, I just want to know if there's any right-now advantage or if all these benefits are dependent upon next-generation adapter cards.

The most significant PC bus architecture change in over a decade, PCI Express is a next-generation system bus providing a high-speed interconnect designed to evolve current PCI technology and address the increasing bandwidth demands of emerging graphics in such next-generation applications as 3D games, professional 3D content creation, high-definition video editing, and more.

Not limited to graphics, PCI Express architecture will also usher in higher bandwidth for a new generation of gigabit Ethernet, high-performance storage controllers, High-Definition video capture controllers, and many other high-performance PC devices.

[Pheaton]

It's just a higher speed bus.

It's mostly used by the newer generation video cards. The PCI-Express bus allows for more bandwidth to travel to and from the card, and also supplies more power to the card than the traditional AGP bus.

There really isnt any performance gain by using PCI-Express right now, as most games don't even use enough bandwidth to be hurt by the 8x AGP bus.

Right now, its basically just an expansion on technology for the future so it has more room to grow.

[StarGate]

To give an example similar to that:

First you had USB 1.1 and all periphery ran on that.
Then they found that some equipment (scanners, cameras, hdd) need a faster system so they made FireWire. So you had that and also USB 1.1 for the rest.

Then came USB 2.0 which is faster then FireWire so now you got 1. even faster scanner, camera, hdd and 2. it is all under ONE hood (bus) again.

Now transfer that example by replacing USB 1.1 with PCI, FireWire with AGP and USB 2.0 with PCI-E

[web2designs]

I don't understand... is PCI-e a replacement for the AGP slot, or it's just a regular slot where you can also plug your Video Card?

[StarGate]

Originally posted by web2designs
I don't understand... is PCI-e a replacement for the AGP slot, or it's just a regular slot where you can also plug your Video Card?

It is PCI "Reloaded" only that it is faster then AGP too....

[Hosemeyer]

It's a replacement for the AGP slot. There is PCI-e 16x which is normally for video cards, PCI-e 8x which is found on server motherboards, not sure what it is used for, and PCI-e 1x which is a replacement for regular pci. More and more new cards will be switched over from pci and agp to PCI-e

[BigBison]

PCI Express isn't just for the graphics adapter. There are three other types of expansion card I can think of which are used with PCI-X:

iSCSI - this is SCSI-over-ethernet, which is replacing FireWire for Network Attached Storage

Clustering - RDMA is Remote Direct Memory Access, I think it's the technology used in InfiniBand cards. This is also known as an SNA bus -- Systems Network Architecture.

Gigabit Ethernet - 1GigE and 10GigE technologies have an awful lot of TCP overhead. They need gobs of main memory bandwidth if they have TOE, and gobs of processor horsepower if they don't.

Opteron SMP's HyperTransport implementation has 12.8GBps bandwidth. Intel's Itanium 2 SMP runs at 10.6GBps. My graphics adapter has an internal bandwidth of 36GBps, externally it runs at 16GBps, PCI-E's bandwidth. So using PCI-X for RDMA, iSCSI and GigE eliminates the bottlenecks these technologies run into on earlier bus architectures.

[DevilDog]

Always some new technology to keep buying too. Thankfully computer systems aren't doubling in power as quickly as they used to at the desktop.

[BigBison]

Psssst... Niagara, from Fujitsu/Sun.

Eight cores, four threads per core, with parallel execution. A single-processor server will have sixteen times the performance of an existing eight-way UltraSPARC IV server while using 90% less power. Operating at 1GHz, with only 3MB L2 cache shared between cores, and a six-stage pipeline compared to 30+ in a Xeon. It also has on-die GigE controllers with TOE. Niagara represents a total re-thinking of CPU design.

http://www.aceshardware.com/read.jsp?id=65000333

:drool: Just because Intel's hit a performance plateau...

Originally posted by DevilDog
Thankfully computer systems aren't doubling in power as quickly as they used to at the desktop.

The shift, is forsaking desktop performance in favor of Thread-Level Parallelism (TLP) microprocessors. The Niagara chip is optimized for integer performance on threaded apps. It will actually run a non-threaded app like Photoshop slower than most current systems.

[BigBison]

Bah, 15-minute edit window. I'd like to add:

The rate of desktop performance improvements will keep plodding along, even slow down some, but server performance is about to take a quantum leap forwards in terms of throughput.

I'd also like to add, I hope 'FujitSun' knows what they're doing. They are systems manufacturers, not processor vendors, so there's some hope. The problem is, if Niagara is successful it would result in a 120x decrease in CPU unit sales, and a 16x decrease in server unit sales. The systems' sales price increase will be under 2x. I'm not sure how to make that work...

[BigBison]

Clarification:

Niagara has 3MB of L2 cache, and no L3 cache. That's less than 500KB cache per core. By comparison, the single core of Intel's latest Xeon has 1MB L2 cache and up to 8MB of L3 cache. The more one overclocks, the more on-chip cache one requires to keep the processor at least 25% utilized under full server load.

Current chip designs use branch prediction and other techniques to reduce these wait states. In a TLP design, as soon as one thread starts waiting, execution is shifted to the next thread waiting its turn. With 32 threads executing in parallel, the chances are awfully high that at least one won't be waiting on anything, even under load. Niagara has no branch predictor, as such trickery isn't needed with a six-stage pipeline and 32 threads to choose from.