Intel Nehalem (microarchitecture)

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Nehalem (pronounced /nəˈheɪləm/^[1]) is the codename for an Intel processor microarchitecture,^[2] successor to the Core microarchitecture. The first processor released with the Nehalem architecture is the desktop Core i7,^[3] which was released on November 15, 2008 in Tokyo and November 17, 2008 in the USA.^[4] The first computer to use Nehalem-based Xeon processors was the Mac Pro workstation announced on March 3, 2009.^[5] Nehalem-based Xeon EX processors for larger servers are expected in Q4 2009.^[6] Mobile Nehalem-based processors will follow in 2010.

Initial Nehalem processors use the same 45 nm manufacturing methods as Penryn. A working system with two Nehalem processors was shown at Intel Developer Forum Fall 2007,^[7] and a large number of Nehalem systems were shown at Computex in June 2008.

The architecture is named after the Nehalem River in Northwest Oregon,^{[citation needed]} which is in turn named after the Nehalem Native American nation in Oregon.^{[citation needed]} The code name itself had been seen on the end of several roadmaps starting in 2000. At that stage it was supposed to be the latest evolution of the NetBurst architecture. Since the abandonment of NetBurst, the codename has been recycled and refers to a completely different project.

Contents 1 Technology 2 Performance and power improvements 3 Variants 3.1 45 nm processor architecture 3.2 32 nm processor architecture "Westmere" 4 Successor 5 See also 6 References 7 External links

[edit] Technology

Various sources have stated the specifications of processors in the Nehalem family:

• Two, four, six, or eight cores
  • 731 million transistors for the quad core variant
• 45 nm manufacturing process
• Integrated memory controller supporting two or three memory channels of DDR3 SDRAM or four FB-DIMM channels
• Integrated graphics processor (IGP) located off-die, but in the same CPU package^[8]
• A new point-to-point processor interconnect, the Intel QuickPath Interconnect, replacing the legacy front side bus
  • In theory, this allows computers to be manufactured without a northbridge, though this has yet to happen in practice.
• Simultaneous multithreading (SMT) by multiple cores which enables two threads per core. Intel calls this hyperthreading. Simultaneous multithreading has not been present on a consumer desktop Intel processor since 2006 with the Pentium 4 and Pentium XE. Intel reintroduced SMT with their Atom Architecture.
• Native (monolithic, i.e. all processor cores on a single die) quad- and octa-core processors^[9]
• The following caches:
  • 32 KB L1 instruction and 32 KB L1 data cache per core
  • 256 KB L2 cache per core
  • 2–3 MB L3 cache per core shared by all cores
• 33 % more in-flight micro-ops than Conroe^[10]
• Second-level branch predictor and second-level Translation Lookaside Buffer^[10]
• Modular blocks of components such as cores that can be added and subtracted for varying market segments^[11]

[edit] Performance and power improvements

It has been reported that Nehalem will have a focus on performance, which accounts for the increased core size.^[12] Compared to Penryn, Nehalem will have:

• 1.1x to 1.25x the single-threaded performance or 1.2x to 2x the multithreaded performance at the same power level
• 30% lower power usage for the same performance
• According to a preview from AnandTech "expect a 20–30% overall advantage over Penryn with a 10% increase in power usage. It looks like Intel is on track to delivering just that in Q4."^[13]
• Per Core, clock-for-clock, Nehalem will provide a 15–20% increase in performance compared to Penryn.^[14]

PC Watch found that a Nehalem "Gainestown" processor has 1.6x the SPECint_rate2006 integer performance and 2.4x the SPECfp_rate_2006 floating-point performance of a 3.0 GHz Xeon X5365 "Clovertown" quad-core processor.^[12]

A 2.93 GHz Nehalem "Bloomfield" system has been used to run a 3DMark Vantage benchmark and gave a CPU score of 17,966.^[15] The 2.66 GHz variant scores 16,294. A 2.4 GHz Core 2 Duo E6600 scores 4,300.^[16]

AnandTech tested the Intel QuickPath Interconnect ("QPI", 4.8 GT/s version) and found the copy bandwidth using triple-channel 1066 MHz DDR3 was 12.0 GB/s. A 3.0 GHz Core 2 Quad system using dual-channel 1066 MHz DDR3 achieved 6.9 GB/s.^[17]

Overclocking will be possible with Bloomfield processors and the X58 chipset. The Lynnfield processor will use a PCH removing the need for a northbridge chipset.^[18]

The Nehalem processors are the first to incorporate the SSE 4.2 SIMD instructions, adding 7 new instructions to the SSE 4.1 set available in the Core 2 series.

[edit] Variants

This section contains information about scheduled or expected future computer chips. It may contain preliminary or speculative information, and may not reflect the final specification of the product.

These tables list all the processors of Nehalem microarchitecture to have been leaked so far. The table is ordered roughly by descending performance, which usually means descending price and power too. Released processors are set in bold.

Notes:

• "Extreme" processors have an unlocked clock multiplier. Thermal Design Power (TDP) values for CPUs with integrated GPUs include the GPU.
• All variants have 64 KiB L1 cache per core, and 256 KiB L2 cache per core.

[edit] 45 nm processor architecture

Codename	Market	Cores (Threads)	Socket	Brand	Processor No.	Clock rate			Turbo	TDP	Interfaces			L3 cache	Release
						Base	Core	Uncore			Chipset	Memory	PCIe
Beckton	MP server	8 (16)	LGA-1567							130/105/90 W	4x QPI	4x [DDR3 with SMB motherboard]	n/a	24 MB	Q1 2010[19]
Gainestown	DP server [20]	4 (8)	LGA-1366	Xeon[21]	W5580	133 MHz	3.2 GHz		Yes	130 W	2x QPI 6.4 GT/s	3x DDR3 1333 MT/s [Note 1]	n/a	8 MB	29 Mar 2009[22]
					X5570, X5560, X5550		2.93, 2.8, 2.66 GHz			95 W
					E5540, E5530, E5520		2.53, 2.4, 2.26 GHz			80 W	2x 5.86 GT/s	3x DDR3 1066 MT/s [Note 1]
					L5520, L5518		2.26 GHz, 2.13 GHz			60 W
		4 (4)			E5506		2.13 GHz		No	80 W	2x 4.80 GT/s	3x DDR3 800 MT/s [Note 1]		4 MB
					L5506		2.13 GHz			60 W
					E5504		2 GHz			80 W
		2 (2)			E5502		1.86 GHz
Bloomfield	UP server [23]	4 (8)	LGA-1366	Xeon [24]	W3570	133 MHz	3.2 GHz		Yes	130 W	1x QPI 6.4 GT/s	3x DDR3 800–1333 MT/s	n/a	8 MB	29 Mar 2009 [24]
					W3540		2.93 GHz				1x QPI 4.8 GT/s	3x DDR3 800–1066 MT/s
					W3520		2.66 GHz
Bloomfield	High Performance Desktop [25]	4 (8)	LGA-1366	Core i7 Extreme	975 [26]	133 MHz	3.33 GHz		Yes	130 W	1x QPI 6.4 GT/s	3x DDR3 800–1066 MT/s (Unlocked since release, supporting XMP)	n/a	8 MB	31 May 2009
					965		3.20 GHz	2.66 GHz							17 Nov 2008
				Core i7	960 [2]		3.2 GHz				1x QPI 4.8 GT/s (Unlocked to 6.4 GT/s since release)				Q4 2009
					950 [26]		3.06 GHz								31 May 2009
					940		2.93 GHz	2.13 GHz							17 Nov 2008
					920		2.66 GHz
Lynnfield	Desktop	4 (8)	LGA-1156/LGA-1155	Core i7	870 [27]	133 MHz	2.93 GHz		Yes	95 W	2x/4x DMI	2x DDR3 1066–1333 MT/s	1x16 / 2x8	8 MB	Q1 2010 [3]
					860		2.8 GHz
		4 (4)		Core i5	750 [28]		2.66 GHz								September 2009
		4 (8)		Core i7			2.13 GHz			65 W or 45 W [4]					Q1 2010
Clarksfield	Mobile	4 (8)	mPGA-989	Core i7 Extreme	920XM	133 MHz	2.0 GHz		Yes	35 W [5] or 45/55 W [6]	2x/4x DMI	2x DDR3 1066–1333 MT/s	1x16 / 2x8	8 MB	September-October 2009
				Core i7	820QM		1.73 GHz
					720QM		1.6 GHz							6 MB

[Note 1] Though there is only one memory controller and it has only three channels, Intel states the Gainestown processors have six memory channels. Gainestown processors have dual QPI links and have a separate set of memory registers for each link^[29] so thereby, in effect, a multiplexed six channel system.

The Havendale and Auburndale variants have been cancelled.^[30]

[edit] 32 nm processor architecture "Westmere"

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Westmere (formerly Nehalem-C) is the name given to the 32 nm die shrink of Nehalem. Westmere should be ready for a late 2009 release provided that Intel stays on target with its roadmap. However, it appears that the bulk of Westmere's versions, excluding mobile versions, will be released sometime in 2010.^[31][32] Westmere's features and improvements from Nehalem have been reported as follows:

• Native six-core and possibly dual-die hex-core 12-core processors. ^[33]
  • The successor to Bloomfield and Gainestown is six-core.
• A new set of instructions that gives over 3x the encryption and decryption rate of Advanced Encryption Standard (AES) processes compared to before.^[34]
  • Delivers six new instructions that will be used by the AES algorithm. Also an instruction called PCLMULQDQ that will perform carry-less multiplication.^[35] These instructions will allow the processor to perform hardware-accelerated encryption, not only resulting in faster execution but also protecting against software targeted attacks.
  • AES-NI may be included in the integrated graphics of Westmere.
• integrated graphics, released at the same time as the processor.
• Improved virtualization latency.^[36]
• New virtualization capability: "VMX Unrestricted mode support" -- which allows 16-bit guests to run. (real mode and big real mode)

Codename	Market	Cores (Threads)	Socket	Brand	Processor No.	Clock rate			TDP	Interfaces			L3 cache	Release	1k Unit Price
						Base	Core	Uncore		Chipset	Memory	PCIe
Gulftown[37]	DP server, extreme desktop	6 (12)	LGA-1366	Core i9 [7]					130 W	2x QPI	3x DDR3 800–1066 MT/s	n/a	12 MB	Q1 2010	$999-$1499
Clarkdale[38]	Mainstream/value desktop	2 (4)	LGA-1156	Core i3, Core i5		133 MHz	2.4 GHz		73 W	2x/4x DMI	2x DDR3 1066-1333 MT/s	1 x16	4 MB	Q4 2009[30]	> $84 [8]
Arrandale[37]	Mainstream/value mobile	2 (4)	mPGA-989	Core i3					18/25/35 W [9]		2x DDR3 800-1066 MT/s [10]		4 MB	Q4 2009[30]

For the desktop, Gulftown is to be an "Extreme Edition" CPU and so will coexist with Bloomfield. [11] It will have Turbo Boost and similar clock speeds to Bloomfield. [12]

Lynnfield and Clarksfield may make the 32 nm transition in the middle of 2010^[37], sometime after Q2 [13], while Beckton will move to 32 nm at the end of 2010.^[39] The 32 nm CPUs will not have significantly different clock speeds compared to 45 nm CPUs.^[40]

The integrated GPUs in Clarkdale and Arrandale are 45 nm, and support switchable graphics.^[30][40] The lowest-power variant of Arrandale may have a 10 W CPU TDP, and a maximum clock speed of 1.6 GHz. [14]

A successor to Bloomfield and entry level server chips are also expected in Q2 2010.^{[30][30][37][39]}

[edit] Successor

The successor to Nehalem and Westmere will be Sandy Bridge, scheduled for release in 2010, according to Intel roadmaps.^[41] The successor to Sandy Bridge will be Haswell, scheduled for release in 2012. It will come with a new cache subsystem, a FMA (fused multiply-add) unit, and a vector coprocessor.^[14]

[edit] See also

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[edit] References

[edit] External links