7 ms·

Intel's Ivy Bridge Architecture Exposed

53 points by yread 15y ago

ricw 15y ago
Interesting how the focus has shifted from performance / frequency to power consumption. I guess Intel is starting to get a bit of a scare of ARM's impending Cortex-A15 attack on the laptop space..
- protomyth 15y ago
  or the low-end server space or Apple getting grumpy...
- miratrix 15y ago
  I think it's more that the "mainstream" computing has moved on from desktops to laptops. Instead of targeting the latest and greatest design at 130W/90W TDP desktop parts and downsizing it to a laptop, they've turned it around and is starting to target 35W TDP as their main platform, then upping the power to turn it into a desktop part. Since power consumption and heat dissipation is becoming an issue also at their top-of-the-line server market, it probably makes much more sense to design things that way. My guess is that high density server design at this point has more in common with laptop-esque power and heat constraints than those of, say, high-end workstations.
- tallanvor 15y ago
  It's not just ARM. Power and cooling costs in server rooms and data centers is a huge consideration, and Intel has to respond to the needs of those customers as well.
  - zokier 15y ago
    I think Intel realized at the end of Netburst era that pushing 150+W of power through small piece of silicon is not trivial anymore. So to have better performance they were forced to improve perf/watt, and that is exactly what they have done since.
  - acdha 15y ago
    Definitely: for at least half a decade most of the HPC people I've worked with or for had power and cooling as the primary constraint, not space or budget. Things like switching to centralized DC (vs. in-server power supplies), getting disks out of cluster nodes, etc. but there was an obvious problem when a rack of servers was roughly comparable BTU-wise to a large gas grill running at maximum.
    - hga 15y ago
      Yeah, buying your hardware is largely a one time capital cost, but power for it and for your cooling is a constant operating cost. Haven't I read somewhere that power is now the largest expense in the lifetime of a "supercomputer"?
      - montecarl 15y ago
        I think for most any computer that is at constant high CPU utilization power will cost more than the hardware over its lifetime. Unless you have very cheap power.
      - acdha 15y ago
        Forget operating costs, one major biological research center I knew of hit (IIRC) 20% of their maximum server space before the power company said they'd need to run a new high-voltage line at $$$ and years of delays even if the neighbors didn't kill it. I believe they were able to jump on the lower-power hardware as that market developed but it certainly got a lot of attention in the community.
        hga 15y ago
        Wow. I suppose they didn't want to move the bulk of their servers because of their sunk costs in space, security, etc. ... but, yeah, I can see that getting a lot of attention. And you implicitly bring up a point I've read about, that power and cooling are now the limiting factors in server spaces. Moore's Law plus the even faster doubling of disk platter capacity (as of late I've read it's doubling every year or so) has allowed us to pack rather a lot in rather small spaces.
- hga 15y ago
  Remember also how they were burned, so to speak, by their Netburst Pentium 4 etc. "marchitecture"; power consumption can be crippling when you push up the speeds and the article comments on both in one sentence, "Ivy Bridge (IVB) is the first chip to use Intel's 22nm tri-gate transistors, which will help scale frequency and reduce power consumption." I for one am very happy with the Sandy Bridge CPU speeds and price/preformance.
  - watmough 15y ago
    Yes, quad-core Sandy Bridge is incredible, even on the low-end of the scale with the i52400. It seems like the power-savings in Ivy Bridge will allow a further transition of this tech down to smaller form-factors. I wonder if the non-premium laptop space will still remain stuck where it is now though? I'm not sure, 5 years on from 2006, what percentage of consumer laptops are significantly faster in use than my MacBook Core Duo.
    - hga 15y ago
      The problem with something like non-premium laptops is that cost tends to be the biggest constraint, so they're not going to give you more than the market demands unless that's "free". But who knows? You can't buy a Sandy Bridge Xeon chip that's less than 3 GHz.... (Although I forget the clock rate of the very low power OEM only part.)
      - watmough 15y ago
        There's some Core 2 Duo-replacements in the 2 core i5s and 7s. http://www.anandtech.com/show/3876/intels-core-2011-mobile-roadmap-revealed-sandy-bridge-part-ii http://www.anandtech.com/show/3876/intels-core-2011-mobile-r... Clocks are 2.2GHz to 2.7GHz, all hyper-threaded. Dual and quad-core. Quite interesting stuff, though I might be annoyed if I bought an i7 laptop then discovered it wasn't a quad-core.
- nextparadigms 15y ago
  I hope that once we have quad core 2.5 Ghz Cortex A15 chips (probably next year), ARM will also start focusing on lowering power consumption after that, or at least split the product line in 2: one that continues to double up the performance every year, while maintaining the same TDP, like they do now, and one where they maintain the performance, but cut the power consumption in half every year. That kind of performance should be more than enough for smartphones, and probably even tablets, though I could see how we might need more on clamshells. But by having a product line that focuses on lowering power consumption every year, while maintaining the performance will also ensure Intel will never catch-up with them in chips with extremely low energy consumption, and in the same time our smartphones will start lasting more and more.
  - wtallis 15y ago
    ARM already has that strategy in place. They don't stop licensing the A8 core when the A9 MPCore hits the market. They're perfectly willing to let you produce an A8 on 22nm silicon if that's what provides the power/performance balance you want. You should take a look at the full list of cores offered by ARM; there's a lot you won't have heard of if you only pay attention to the flagship phones and tablets.
  - Someone 15y ago
    ", or at least split the product line in 2: one that continues to double up the performance every year, while maintaining the same TDP, like they do now, and one where they maintain the performance, but cut the power consumption in half every year." That is more of a tactic than a strategy. After 3-odd years, there would be a 10 times performance difference between the 'fast' and the 'cool' lines. Chances are there is room between them. Also, I think is more economical to produce old designs at new technologies for the 'cool' line than to design new 'cool' chips from scratch. That would likely get you 90% of the goal for 10% of the costs. That 90% probably is sufficient, too, as CPU power usage typically is only a fraction of system power usage. I think that applies even to most embedded stuff for which an ARM is appropriate (ignoring on-chip audio and video decoding hardware)
cletus 15y ago
The evolution of technology has certainly been interesting. I remember a lecturer once told me that everything old is new again. Basically we go in cycles. We started with mainframes, then mini-computers and then micro-computers (PCs/Macs). What happened in the last 10 years? Through the "cloud" we basically went back to large computers and timesharing again. Another turning point in the last 10 years is that basically any PC made since 2000 will probably be sufficient for what most normal users want. We get increasingly powerful CPUs that most people just don't need. This is part of the reason for the move to lower power consumption. A smaller form factor and lighter computer is something most people care about. Having 6 cores instead of 4 just isn't. Many pundits have predicted that Web applications will take over. 5-10 years ago there was a reasonable basis for this opinion. Computers would get increasingly powerful and that headroom would make the otherwise horribly inefficient Javascript medium (compared to the compiled languages like C/C++ or even the bytecode languages like Java/C#) dominant as the inefficiencies become irrelevant. The rise of native apps on mobile is another example of this cycle. Part of this is that native apps have access to libraries that Web pages simply don't but part of it really is performance and the fact that performance once again matters. Personally I find the manufacturing of chips at 22nm to be simply amazing. When I started paying attention to this stuff IIRC the 386/486 were done on 500nm+ lithography. I do wonder what the future holds because that number just can't physically get much smaller (with current lithographic techniques). It's amazing how much power a small chip can get now. I have one of the latest Macbook Airs and it can decode 10 video streams without the fan coming on. A friend has the Core 2 Duo MBA (last year's) and his machine is dying under the same load.
- zokier 15y ago
  Just a note, but imho video decoding these days is not very good benchmark on performance, as it is usually handled by somewhat specialized hardware decoder instead the general purpose CPU (even if they both are integrated on the same physical chip).
  - 0x12 15y ago
    Forgive me, but I'm not familiar with general purpose CPU's that 'usually' have a specialized hardware decoder on board for video decoding. Which CPUs specifically do you mean? Dear downvoters, thank you very much for showing that HN is a place where simply asking a question is already reason to get downvoted.
hga 15y ago
The thing I found most interesting was "supervisory mode execution protection (SMEP)", AKA rings, available in 64 bit as well as 32 bit modes. This is something that AMD punted in their 64 bit macroarchitecture (which Intel was then forced to copy) and is sorely missed for various low level stuff. Unfortunately the long 64 bits interregnum without rings means it will be a long time before you can depend on others being able to run software depending on it.
- marshray 15y ago
  What's an example of something that depends on this?
  - hga 15y ago
    I remember that some things depended upon it before AMD came out with their 64 bit architecture, but not what they are. One thing I do know it's useful for is allowing your GC to run in an intermediate level of privilege between user and supervisor code. Also, if you do it right (i.e. Multics) a system call can be much cheaper because the supervisor isn't running in its own address space etc. Instead, your user level code calls a carefully vetted bit of system gateway code that has a foot in both rings.
    - bdonlan 15y ago
      At least on Linux, there is no address space change when you make a syscall - entering ring 0 _grants access_ to the top half of the address space, where kernel code and data lies, but there's no change in page tables (with all the overhead that implies). As for code having a foot in both rings, Linux has its VDSO (and Windows has ntdll) running at a user privilege level; I don't really see how having an additional intermediate level would help much.
      - marshray 15y ago
        I'm not the world's expert on this kind of thing but I don't think I've seen anything much more complicated than the basic 'supervisor mode bit' get much use in practice. Even the venerable 286 (yes 2 not 386) had this four ring model and 'tasks' which continue to exist as vestigial organs of the architecture. Not used by anything I'm aware of.
Retric 15y ago
I kept reading this and wondering why there was going to be so little improvement when dropping down to 22nm. Turns out they are mostly just bumping the GPU which is useless to anyone with a discrete graphics card. "Intel isn't disclosing the die split but there are more execution units this round (16 up from 12 in SNB) so it would appear as if the GPU occupies a greater percentage of the die than it did last generation. It's not near a 50/50 split yet, but it's continued indication that Intel is taking GPU performance seriously."
- eliben 15y ago
  What percentage of users _use_ a discrete graphics card, though? Especially on ultra-light laptops?
  - mappu 15y ago
    And what percentage of Ivy Bridge users are going to be using ultra-light laptops? It's a desktop part as well.
    - eliben 15y ago
      It is, but I would guess the majority of desktop users are in offices and will be just fine with the on-core CPU (keep in mind it is pretty powerful - the current ones are on par with medium-low range discrete cards, and Ivy Bridge's are likely to be much better). What really is the percentage of gamers and video editors that need the high-end GPUs?
      - zokier 15y ago
        Saying that current integrated GPUs are on par with medium-low range is still generous. Based on the article, Ivy Bridge GPU is approx 60% faster than in Sandy Bridge. I'd estimate that it would it near the performance of Radeon 6450, which is the weakest discrete card in the series. That said, I agree that with Ivy Bridge, the GPU performance will be good enough for a lot of uses.
- 15y ago
onan_barbarian 15y ago
Whoa: mov is a rename and doesn't take a uop. In the leadup to Sandy Bridge this seemed hinted at (the SB renamer handles 'zeroing' registers if you use the right cliche) but SB still didn't do movs as renames. The fact that Ivy Bridge does is pretty cool, and more applicable than a shift to 3-operand forms, as it won't need a recompile to run older code more quickly. This is pretty cool, at least for those of us who care about this sort of nonsense. I think I have a performance-critical 105-operation loop somewhere that might shed about 8-10 pointless execution slots burned on movs...

53 points by yread 15y ago

ricw 15y ago

Interesting how the focus has shifted from performance / frequency to power consumption. I guess Intel is starting to get a bit of a scare of ARM's impending Cortex-A15 attack on the laptop space..

protomyth 15y ago
or the low-end server space or Apple getting grumpy...
miratrix 15y ago
I think it's more that the "mainstream" computing has moved on from desktops to laptops. Instead of targeting the latest and greatest design at 130W/90W TDP desktop parts and downsizing it to a laptop, they've turned it around and is starting to target 35W TDP as their main platform, then upping the power to turn it into a desktop part. Since power consumption and heat dissipation is becoming an issue also at their top-of-the-line server market, it probably makes much more sense to design things that way. My guess is that high density server design at this point has more in common with laptop-esque power and heat constraints than those of, say, high-end workstations.
tallanvor 15y ago
It's not just ARM. Power and cooling costs in server rooms and data centers is a huge consideration, and Intel has to respond to the needs of those customers as well.
- zokier 15y ago
  I think Intel realized at the end of Netburst era that pushing 150+W of power through small piece of silicon is not trivial anymore. So to have better performance they were forced to improve perf/watt, and that is exactly what they have done since.
- acdha 15y ago
  Definitely: for at least half a decade most of the HPC people I've worked with or for had power and cooling as the primary constraint, not space or budget. Things like switching to centralized DC (vs. in-server power supplies), getting disks out of cluster nodes, etc. but there was an obvious problem when a rack of servers was roughly comparable BTU-wise to a large gas grill running at maximum.
  - hga 15y ago
    Yeah, buying your hardware is largely a one time capital cost, but power for it and for your cooling is a constant operating cost. Haven't I read somewhere that power is now the largest expense in the lifetime of a "supercomputer"?
    - montecarl 15y ago
      I think for most any computer that is at constant high CPU utilization power will cost more than the hardware over its lifetime. Unless you have very cheap power.
    - acdha 15y ago
      Forget operating costs, one major biological research center I knew of hit (IIRC) 20% of their maximum server space before the power company said they'd need to run a new high-voltage line at $$$ and years of delays even if the neighbors didn't kill it. I believe they were able to jump on the lower-power hardware as that market developed but it certainly got a lot of attention in the community.
      - hga 15y ago
        Wow. I suppose they didn't want to move the bulk of their servers because of their sunk costs in space, security, etc. ... but, yeah, I can see that getting a lot of attention. And you implicitly bring up a point I've read about, that power and cooling are now the limiting factors in server spaces. Moore's Law plus the even faster doubling of disk platter capacity (as of late I've read it's doubling every year or so) has allowed us to pack rather a lot in rather small spaces.
hga 15y ago
Remember also how they were burned, so to speak, by their Netburst Pentium 4 etc. "marchitecture"; power consumption can be crippling when you push up the speeds and the article comments on both in one sentence, "Ivy Bridge (IVB) is the first chip to use Intel's 22nm tri-gate transistors, which will help scale frequency and reduce power consumption." I for one am very happy with the Sandy Bridge CPU speeds and price/preformance.
- watmough 15y ago
  Yes, quad-core Sandy Bridge is incredible, even on the low-end of the scale with the i52400. It seems like the power-savings in Ivy Bridge will allow a further transition of this tech down to smaller form-factors. I wonder if the non-premium laptop space will still remain stuck where it is now though? I'm not sure, 5 years on from 2006, what percentage of consumer laptops are significantly faster in use than my MacBook Core Duo.
  - hga 15y ago
    The problem with something like non-premium laptops is that cost tends to be the biggest constraint, so they're not going to give you more than the market demands unless that's "free". But who knows? You can't buy a Sandy Bridge Xeon chip that's less than 3 GHz.... (Although I forget the clock rate of the very low power OEM only part.)
    - watmough 15y ago
      There's some Core 2 Duo-replacements in the 2 core i5s and 7s. http://www.anandtech.com/show/3876/intels-core-2011-mobile-roadmap-revealed-sandy-bridge-part-ii http://www.anandtech.com/show/3876/intels-core-2011-mobile-r... Clocks are 2.2GHz to 2.7GHz, all hyper-threaded. Dual and quad-core. Quite interesting stuff, though I might be annoyed if I bought an i7 laptop then discovered it wasn't a quad-core.
nextparadigms 15y ago
I hope that once we have quad core 2.5 Ghz Cortex A15 chips (probably next year), ARM will also start focusing on lowering power consumption after that, or at least split the product line in 2: one that continues to double up the performance every year, while maintaining the same TDP, like they do now, and one where they maintain the performance, but cut the power consumption in half every year. That kind of performance should be more than enough for smartphones, and probably even tablets, though I could see how we might need more on clamshells. But by having a product line that focuses on lowering power consumption every year, while maintaining the performance will also ensure Intel will never catch-up with them in chips with extremely low energy consumption, and in the same time our smartphones will start lasting more and more.
- wtallis 15y ago
  ARM already has that strategy in place. They don't stop licensing the A8 core when the A9 MPCore hits the market. They're perfectly willing to let you produce an A8 on 22nm silicon if that's what provides the power/performance balance you want. You should take a look at the full list of cores offered by ARM; there's a lot you won't have heard of if you only pay attention to the flagship phones and tablets.
- Someone 15y ago
  ", or at least split the product line in 2: one that continues to double up the performance every year, while maintaining the same TDP, like they do now, and one where they maintain the performance, but cut the power consumption in half every year." That is more of a tactic than a strategy. After 3-odd years, there would be a 10 times performance difference between the 'fast' and the 'cool' lines. Chances are there is room between them. Also, I think is more economical to produce old designs at new technologies for the 'cool' line than to design new 'cool' chips from scratch. That would likely get you 90% of the goal for 10% of the costs. That 90% probably is sufficient, too, as CPU power usage typically is only a fraction of system power usage. I think that applies even to most embedded stuff for which an ARM is appropriate (ignoring on-chip audio and video decoding hardware)

cletus 15y ago

The evolution of technology has certainly been interesting. I remember a lecturer once told me that everything old is new again. Basically we go in cycles. We started with mainframes, then mini-computers and then micro-computers (PCs/Macs). What happened in the last 10 years? Through the "cloud" we basically went back to large computers and timesharing again. Another turning point in the last 10 years is that basically any PC made since 2000 will probably be sufficient for what most normal users want. We get increasingly powerful CPUs that most people just don't need. This is part of the reason for the move to lower power consumption. A smaller form factor and lighter computer is something most people care about. Having 6 cores instead of 4 just isn't. Many pundits have predicted that Web applications will take over. 5-10 years ago there was a reasonable basis for this opinion. Computers would get increasingly powerful and that headroom would make the otherwise horribly inefficient Javascript medium (compared to the compiled languages like C/C++ or even the bytecode languages like Java/C#) dominant as the inefficiencies become irrelevant. The rise of native apps on mobile is another example of this cycle. Part of this is that native apps have access to libraries that Web pages simply don't but part of it really is performance and the fact that performance once again matters. Personally I find the manufacturing of chips at 22nm to be simply amazing. When I started paying attention to this stuff IIRC the 386/486 were done on 500nm+ lithography. I do wonder what the future holds because that number just can't physically get much smaller (with current lithographic techniques). It's amazing how much power a small chip can get now. I have one of the latest Macbook Airs and it can decode 10 video streams without the fan coming on. A friend has the Core 2 Duo MBA (last year's) and his machine is dying under the same load.

zokier 15y ago
Just a note, but imho video decoding these days is not very good benchmark on performance, as it is usually handled by somewhat specialized hardware decoder instead the general purpose CPU (even if they both are integrated on the same physical chip).
- 0x12 15y ago
  Forgive me, but I'm not familiar with general purpose CPU's that 'usually' have a specialized hardware decoder on board for video decoding. Which CPUs specifically do you mean? Dear downvoters, thank you very much for showing that HN is a place where simply asking a question is already reason to get downvoted.

hga 15y ago

The thing I found most interesting was "supervisory mode execution protection (SMEP)", AKA rings, available in 64 bit as well as 32 bit modes. This is something that AMD punted in their 64 bit macroarchitecture (which Intel was then forced to copy) and is sorely missed for various low level stuff. Unfortunately the long 64 bits interregnum without rings means it will be a long time before you can depend on others being able to run software depending on it.

marshray 15y ago
What's an example of something that depends on this?
- hga 15y ago
  I remember that some things depended upon it before AMD came out with their 64 bit architecture, but not what they are. One thing I do know it's useful for is allowing your GC to run in an intermediate level of privilege between user and supervisor code. Also, if you do it right (i.e. Multics) a system call can be much cheaper because the supervisor isn't running in its own address space etc. Instead, your user level code calls a carefully vetted bit of system gateway code that has a foot in both rings.
  - bdonlan 15y ago
    At least on Linux, there is no address space change when you make a syscall - entering ring 0 _grants access_ to the top half of the address space, where kernel code and data lies, but there's no change in page tables (with all the overhead that implies). As for code having a foot in both rings, Linux has its VDSO (and Windows has ntdll) running at a user privilege level; I don't really see how having an additional intermediate level would help much.
    - marshray 15y ago
      I'm not the world's expert on this kind of thing but I don't think I've seen anything much more complicated than the basic 'supervisor mode bit' get much use in practice. Even the venerable 286 (yes 2 not 386) had this four ring model and 'tasks' which continue to exist as vestigial organs of the architecture. Not used by anything I'm aware of.

Retric 15y ago

I kept reading this and wondering why there was going to be so little improvement when dropping down to 22nm. Turns out they are mostly just bumping the GPU which is useless to anyone with a discrete graphics card. "Intel isn't disclosing the die split but there are more execution units this round (16 up from 12 in SNB) so it would appear as if the GPU occupies a greater percentage of the die than it did last generation. It's not near a 50/50 split yet, but it's continued indication that Intel is taking GPU performance seriously."

eliben 15y ago
What percentage of users _use_ a discrete graphics card, though? Especially on ultra-light laptops?
- mappu 15y ago
  And what percentage of Ivy Bridge users are going to be using ultra-light laptops? It's a desktop part as well.
  - eliben 15y ago
    It is, but I would guess the majority of desktop users are in offices and will be just fine with the on-core CPU (keep in mind it is pretty powerful - the current ones are on par with medium-low range discrete cards, and Ivy Bridge's are likely to be much better). What really is the percentage of gamers and video editors that need the high-end GPUs?
    - zokier 15y ago
      Saying that current integrated GPUs are on par with medium-low range is still generous. Based on the article, Ivy Bridge GPU is approx 60% faster than in Sandy Bridge. I'd estimate that it would it near the performance of Radeon 6450, which is the weakest discrete card in the series. That said, I agree that with Ivy Bridge, the GPU performance will be good enough for a lot of uses.
15y ago

onan_barbarian 15y ago

Whoa: mov is a rename and doesn't take a uop. In the leadup to Sandy Bridge this seemed hinted at (the SB renamer handles 'zeroing' registers if you use the right cliche) but SB still didn't do movs as renames. The fact that Ivy Bridge does is pretty cool, and more applicable than a shift to 3-operand forms, as it won't need a recompile to run older code more quickly. This is pretty cool, at least for those of us who care about this sort of nonsense. I think I have a performance-critical 105-operation loop somewhere that might shed about 8-10 pointless execution slots burned on movs...