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AMD Unleashes First-Ever 5 GHz Processor
- louthy 13y ago> "FX-9590: Eight “Piledriver” cores, 5 GHz Max Turbo " Ridiculous name. Maybe if they put a 'Go faster stripe' on the top of the chip people will believe it goes even faster!
- rbanffy 13y agoThe "turbo" is probably there because of the amount of air that must flow through the radiator.
- sp332 13y agoThe CPU has different clock speeds depending on how much it is being used. The upper limit is set by thermal and power constraints. If you're using all the cores, the limit is relatively low. If you're only using one or two cores, the power management system will clock them higher. Since the higher clock speed is only available under certain workloads, it's called "Turbo".
- louthy 13y agoOh I appreciate all of that. But in combination with all of the other superlatives, it's frankly ludicrous. AMD Exec 1: "Hmm, which superlatives can we use to sell this 'slightly more powerful chip'?" AMD Exec 2: "Err... hmm... how about... ALL OF THEM?!" AMD Exec 1: "Do you know, you're a freaking genius!!"
- SteveTickle 13y ago"FX", "PileDriver", "Max", "Turbo" ??? Whats next? obviously, "Super", "Mega", "Ultra", "Extra"?
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- icegreentea 13y agoThe name is FX-9590. It has 8 compute cores. AMD's internal designation for this generation is "Piledriver". They've chosen to name their high-end compute family after construction equipment (their previous were named after racing tracks). 5 GHz Max Turbo is also not part of the name, it is a description of its performance. It's "baseline" performance is probably something like 4GHz or something (pulling out of my ass). The Max Turbo refers to that using their thermal management system, they can peak at least one of their cores to 5GHz for some period of time. The "Max" is in there because there are intermediate turbo speeds for varying thermal situations and CPU loads.
- moe 13y agoI really wish CPU vendors would simply name their products after relevant benchmarks. E.g. 'Intel PassMark 14490/135W'. Or 'AMD PassMark 9140/125W'. Sounds nearly as fancy, makes the same amount of sense to the layman, and saves the rest of us a bit of time.
- pavlov 13y agoAMD used to do something like this back in the K5 era. Instead of advertising megahertz, the processors were sold based on a "performance rating" which attempted to match them up to equivalent Pentium chips based on a set of benchmarks. So a K5 PR-200 was actually a 133MHz chip, but it could match or exceed a Pentium 200MHz in some well-selected benchmarks.
- iso8859-1 13y agoThere is no such thing as a _universally_ "relevant benchmark". They will never agree on a testing suite since performance varies too much. They have no reason to believe the test manufacturer is impartial.
- vacri 13y agoWhen you're done convincing them, can you convince the GPU makers as well? It's crazytown over there. At least the network switch makers have a sort of internal consistency, though you still have to learn individual vendors' styles.
- nakedrobot2 13y ago"piledriver"? Good grief! What are the next models called? Doggy Style? Missionary?
- sp332 13y agoIt was a wrestling move before it was a sex position. And the wrestling move was named after an actual tool to drive piles. https://en.wikipedia.org/wiki/Pile_driver https://en.wikipedia.org/wiki/Pile_driver
- marshray 13y agoIt's a sex position? Kids these days and their newfangled terminology. Still, it seems unlikely that no one had ever snickered about the phallic symbolism of the construction equipment of the term's original usage.
- joyeuse6701 13y agoYou sir, should be in marketing. If you put a glistening racing stripe on the packaging, I'd make a guess you'd get 10% more in sales.
- Everlag 13y agoYes AMD, we all know you like your big numbers like core counts and clock speed. It'd, however, be just excellent if you could put out a product whose single threaded performance isn't garbage. I mean, thubans are beating your newest and greatest! But at least you can say you got the bigger cache, clockspeed, core count, and debt than intel.
- Stolpe 13y agoIn other news: PCs now even more versatile. Now also replace radiators.
- venomsnake 13y agoIt has been like that for a while ... in 2000-ish we were calling Athlon Kotlon (Kotlon is stove in bulgarian)
- freehunter 13y agoIn the mid 2000s I was running a Prescott oven in my room.
- sliverstorm 13y agoJust wrap that computer case in tin foil, and you got a makeshift oven!
- vidarh 13y agoThere's the story that ARM at one point took a "pizza oven" using Intel CPU's as heating elements to trade shows back in the early 90's.
- thrownaway2424 13y agoBack in the early 90s, it was an actual scandal that the Pentium had such a huge heat sink. The magazines (at that time, computing magazines were quite popular) were joking that next they'd put a fan on the CPU. Haha. Those were the days, really, because there was still the possibility that in the future you'd have any damned thing in your computer, not necessarily an x86. You could have an Alpha or a SPARC or PPC or maybe an i960. And it would be silent and use no power and you'd install it in your bitchin' conversion van.
- adestefan 13y agoI miss the P4 I used to have at an old job. It kept my feet nice and warm in the winter.
- rbanffy 13y agoWasn't IBM's POWER in this range already?
- profquail 13y agoYes, according to Wikipedia, IBM was shipping 5.0GHz POWER6 processors by 2008: https://en.wikipedia.org/wiki/POWER6 https://en.wikipedia.org/wiki/POWER6 The article cited in the Wikipedia entry is dated 08-Apr-2008: http://www.theregister.co.uk/2008/04/08/ibm_595_water/ http://www.theregister.co.uk/2008/04/08/ibm_595_water/
- apaprocki 13y agoDon't let the numbers fool you, though. POWER6 achieved those speeds due to a change in chip architecture that actually wound up making them worse processors than the much lower clocked POWER5s in a lot of situations. IBM reversed course and changed the chip architecture back for the POWER7s, which are clocked lower and outperform the POWER6s.
- bretpiatt 13y agoI'm not an expert here but it looks like IBM is back up to shipping 5.5Ghz chips in the EC12 as of December 2012. Are these still POWER6 chips as an option or fixed and faster POWER7? PDF Redbook reference: http://www.redbooks.ibm.com/redbooks/pdfs/sg248050.pdf http://www.redbooks.ibm.com/redbooks/pdfs/sg248050.pdf
- drcode 13y agoDoes it really qualify as a 5 GHz processor if it only runs at that speed in Turbo mode? (which I assume can only kick in for a few milliseconds...) What is the "normal" speed that it can maintain for more reasonable time periods? How come this isn't mentioned in the press release?
- Retric 13y agoTurbo mode is limited by heat so with cooling you can stay in turbo mode. PS: Intel and Nvidea do the same thing. http://www.techarp.com/showarticle.aspx?artno=745&pgno=1 http://www.techarp.com/showarticle.aspx?artno=745&pgno=1
- deelowe 13y agoUnfortunately, heat is precisely the reason why no one's competing on clock rates any longer. It's called a thermal wall for a reason. To be honest, this is a pretty sad thing for AMD to do. It'll be interesting to see what kind of coolers will be capable of running this thing at 5ghz all the time, if any. And, if even it is possible to run this in turbo mode all the time, what next? Can AMD make a 5.1 chip? 5.2? What would they need to compromise on?
- leot 13y agohttp://en.wikipedia.org/wiki/Reversible_computing http://en.wikipedia.org/wiki/Reversible_computing
- api 13y agoIf older chips from Intel and AMD could be overclocked to twice their baseline rates with high-end cooling, I wonder what you could clock this beast up to? And yes there is a market for this. There are certain workloads that are simply not parallelizable -- they're linear chains of dependencies where the output of the first process goes into the second and so on and each step depends on all N-1 steps.
- DanBC 13y ago
- tibbon 13y agoI remember like ~10 years ago on Slashdot some people overclocking to 7-8ghz. Of course this was on single core chips, but we've really pretty much completely stalled on the mhz progression haven't we?
- mistercow 13y agoClock speed is not a meaningful end unto itself, and that's why it stalled. It was used as a proxy for speed for many years, and this led to its rampant inflation. Instructions per second (IPS) is a more meaningful metric for CPU speed, and that has by no means stalled, even on a per-core basis.
- jmngomes 13y agoAlso, I think there are some physical limitations that keep chips below a certain clock speed. Besides, the bet has been on "smarter instead of faster", i.e. producing chips that suit our computing needs, which are more adequately supported by parallel processing. High performance cores are useful for problems that are hard to paralellize, but so far it seems that the breakthrough only occurs when a new approach to the problem makes it feasible on multiprocessing platforms (e.g. graph processing is hard to paralellize due to dependencies among graph nodes, Pregel and similar offer a different approach)...a 50GHz CPU won't save you if you need to process a huge graph (i.e. billions of nodes) on a single thread, it'll always take a lot of time. As to the "record", I think IBM already had a Series Z that is over 5GHz.
- sliverstorm 13y agoI think there are some physical limitations that keep chips below a certain clock speed. Not hard limits, but yes, to my knowledge it is primarily physics that keep chips where they are. The requirements for power and heat dissipation start to balloon.
- drzaiusapelord 13y agoI don't think these are practical limitations, more like limitations to be able to sell laptops and desktops. If we told intel that they could burn up to 350watts on the CPU and a 25lbs heatsink was acceptable, we'd probably have 10ghz processors. Problem is, there isn't a large market for that. Home users don't want a big ugly and noisy box and server buyers would prefer power and heat savings. Supercomputers just tie all this stuff together instead of creating some monster single-core. Actually, this was the strategy with the pentium 4. It was a fast and power hungry single-core. Turns out, efficiency per cycle and multicore are just superior solutions.
- leeoniya 13y agoand here i was hoping never to see a high-clock-speed headline again...(supercomputers excluded)
- fchief 13y agoI guess their marketing was out of other ideas and just went back to the well one more time. It has probably been 10 years now since I really considered CPU clock speed as a factor when buying a computer.
- venomsnake 13y agoCan you hear it - the shrieks of all those D-14 and Phantex-s screaming. I would like to see review though. And pricing. If it has decent single thread performance and that number of cores with all next gen games being multhithreaded by default it could be a compelling processor if it is in the 4770 price range.
- zanny 13y agoNot really, because the AMD 8 physical core layout is still 4 packages of 2 register sets sharing ALU and FPU. It is exactly like a hyperthreaded Intel part, but Intel has much better per clock performance. That, and I see next gen games more favoring openCL / GL 4.3 compute shaders to offload all their parallel workloads than to aggressively optimize for greater than 4 core processors. Your returns on moving traditionally CPU bound workloads (per agent logic, path finding, collision detection) to compute class GPUs (when available, with the cpu fallback for now) gives you significantly more returns than optimizing for the CPU. Also, you can take a 4770k to near 5ghz on air. This part is already pushing the thermal limits of the Bulldozer architecture, AMD is just fabbing them out this high speed because they are floundering in this low-per clock performance rut the entire architecture put them in. Now, I would point any budget oriented gamer to the 4 or 6 core AMD models around $120 - 130, because since they are all unlocked, you can get real performance gains (but terrible power efficiency) over Intel parts below the 4 core unlocked part they put out each generation. Since they are effectively 2 / 3 module parts, they are well suited for the next gen of GPGPU everything in the engine and let the CPU do control flow. If you even approach $200, the performance gains from jumping from any non-K part to a 4.8ghz 4570k are huge, and that alone outclasses every AMD cpu for gaming, but does trade blows on some titles with the 8 core parts.
- e12e 13y agoIt'll be interesting to see if AMD cornering both the new xbox and ps4 has an effect on game engines for the pc as well -- specifically if the tuning that probably will go into console versions will translate to pc -- and whether or not Intel (and nvidia) will end up being penalized as a result.
- IanChiles 13y agoI seem to recall reading that these processors would have a 220W TDP - which makes the whole 5ghz thing much much less impressive...
- jdavid 13y agoAgreed, I don't know how you are going to cool that thing quietly or cheaply. I think the thermal load would be less on two cpu chips running at 2/3-rds the GHz. It might be cheaper to build as well.
- Moto7451 13y agoI'm yet to find an actual source for that figure whenever it comes up. Is it just some tech site comment section spitballing or did they actually disclose the TDP?
- VLM 13y agoIf there's a dimensioned pix of the heatsink, a bored enough engineer could calculate the theoretical degC/W rating of the heatsink, and given a presumably constant deltaT, there's your wattage. Doesn't have to be dimensioned that accurately. To a first approximation a 1% error in surface area would be about a 1% error in TDP. I'd like to see very high temp CPU technology. That would be an interesting, challenging direction for hardware tech to move. A tiny lightweight 5 deg C/W heatsink is plenty if you're allowed to run at, say, vacuum tube redhot glow temperatures. I'm well aware of the solid state physics challenges of this, that's why I think it would be very interesting to see if anyone could pull it off.
- marshray 13y agoI doubt that a heatsink on an engineering-sample test board would be sized within a 1% margin. Seems more likely they'd be error generously on the side of big.
- brigade 13y agoNeither - the 5GHz chips were rumored for a while, and the rumors always mentioned 220W TDP. Since the first half of the rumor came true, it's fairly likely the second half will too.
- josephagoss 13y agoWhat's the MIPS for this CPU?
- icegreentea 13y agoThis is pretty important for AMD because they've been having a terrible time matching Intel at per cycle efficiency. Basically, ever since the core i series started, AMD has been behind at single threaded performance, especially when going clock for clock. They've been trying to make up for it by both offering more cores/threads than comparably priced Intel components, as well as trying to scale their clock rates. Unfortunately for AMD, their last few generations have actually been falling short on their attempts to boost clock rates, as a result, when comparing comparably priced AMD and Intel chips, while AMD would typically have a clock speed advantage, it would often not be enough to overcome Intel's efficiency. This product release is kind of an attempt to show that AMD can actually deliver on their planned strategy. As for why AMD is going for this route, rather than trying to beat Intel in per clock efficiency? Probably because AMD's resources are severely limited compared to Intel, and this approach offered lower risk at lower cost.
- Freaky 13y ago> As for why AMD is going for this route, rather than trying to beat Intel in per clock efficiency? Well, because clock speeds are something they can improve now, and not in $n years time when their next major microarchitecture is ready. Intel had the exact same problem with the Pentium 4, and they were similarly stuck with minor tweaks and desperately increasing clock rates for years before Core was ready.
- Lagged2Death 13y agoI wish I had a cite for this. It was my understanding that P-IV was originally conceived as an architecture that could be clocked up and up for years to come. Developing a new architecture is expensive and risky (see P-IV, Itanium), so the hope was to design something that would scale up so well as manufacturing improved that a few generations of architectures could be skipped, so to speak. They had hoped the P-IV would eventually reach 10GHz or so. Which made it OK that P-IV retried fewer instructions per clock than the P-III that came before. Scaling up like that isn't such a radical idea; the P6/i686 architecture behind the Pentium Pro, Pentium II and Pentium III had spanned a spectrum from 150MHz to 1.4GHz, after all, nearly an order of magnitude. But it turned out that somewhere between 3 and 4 GHz, things got really difficult. "Minor tweaks and desperately increasing clock rates" was more or less the P-IV plan from the get go. It just turned out not to work.
- Ziomislaw 13y agoyaay, I am eagerly awaiting for intel to catch up :) (so I could buy quality stuff that does not hang or overheat)
- userulluipeste 13y agoQ: What will a more powerful CPU core do in a comparatively slow environment that is the rest of the computer? A: Wait faster!
- bcoates 13y agoA lot of that comparative slowness was caused by mechanical storage, replacing it with parallel and lower-latency SSDs makes it a lot easier to get full use out of more and faster cores. It doesn't cost much to set up a system that's completely CPU-limited on OLAP database-like workloads these days. I suspect that as more software stops being optimized for ~10ms serial disk I/O with huge caches this will become more common and more and faster cores will be a big(er) deal.
- jevinskie 13y agoCompiling big projects (10+ minutes) is still a big use case for a beefy CPU.
- e12e 13y agoSome comments from Anandtech: http://www.anandtech.com/show/7066/amd-announces-fx9590-and-fx9370-return-of-the-ghz-race http://www.anandtech.com/show/7066/amd-announces-fx9590-and-... Based on an old review: http://www.anandtech.com/show/6396/the-vishera-review-amd-fx8350-fx8320-fx6300-and-fx4300-tested/ http://www.anandtech.com/show/6396/the-vishera-review-amd-fx... and single thread performance: http://www.anandtech.com/show/6396/the-vishera-review-amd-fx8350-fx8320-fx6300-and-fx4300-tested/4 http://www.anandtech.com/show/6396/the-vishera-review-amd-fx... If single threaded scales linearly with turbo frequency (and it looks like it might): The FX8320 (turbo boost 4.0Ghz) scores 240.7, while the FX8350 (turbo boost 4.2Ghz) scores 252.1: The difference aligns quite nicely: (240.7/4)4.2~252.74 And for 5Ghz should give about: (240.7/4)5~300.88 This is still lower than intel's i5 3570k (302.2 - Turbo 3.8Ghz) and i7 3770k (312.4 - Turbo 3.9Ghz) And Haswell has even higher performance: http://www.anandtech.com/show/7003/the-haswell-review-intel-core-i74770k-i54560k-tested http://www.anandtech.com/show/7003/the-haswell-review-intel-...
- AnthonyMouse 13y agoYou're comparing the performance of the respective top of the line models. That only matters for bragging rights. Most people don't buy that one, which leaves AMD open to sell chips to people who would have bought midrange Intel chips -- or people who are willing to sacrifice 312.4/300.88 -> ~3.8% performance (which is almost certainly within the margin of error) in order to keep competition alive or because AMD offers a lower price.
- e12e 13y agoWell, I just wanted to guess at what that 5Ghz announcement actually would mean in terms of performance. I'm not convinced ~11 pixels per second is within the margin of error (the numbers were from the single threaded povray test) -- but 3.8% difference certainly mean very little in the real world. I'd guess it falls within the bracket that is measurable but ignorable ;-) Also, the "5Ghz chip" will most certainly be AMDs top of the line model?
- trotsky 13y agoBased on how bulldozer performed, it'll end up that sure it's 5ghz, but did we mention all our instructions take two times the number of clocks now? Virtualiztion host performance on our 8 core bulldozer (esx 5.1, private kbs from vmware to try to help, 32gb ram, rad10 zfs san) was so bad (think p4 era) that we finally tracked down how to force the cpu into only using 4 cores, one per real fp core. The reality is that there is no mainstream scheduler out that that can efficienty use cores set up like that, especially with the long pipelines. I'm not sure it can't be done, but what improvements have been made have been minimal, or just in an academic/not a real os situation. That's why Intel ships a compiler, duh. It is true that the # one thing holding that part back was the raw clock speed (as long as you view it more like a 4 core, 8 thread part ala Intel), but i've gone back to speccing intel - it's just not worth being that much of a ginae pig for a firm thats basically trying to scrape by until the arm64 parts start getting stamped.
- sliverstorm 13y agowe finally tracked down how to force the cpu into only using 4 cores Was the issue the shared fp units, or the turbo-core? I wonder if you can disable the turbo-core?
- mitchty 13y agoIf it was anything like the Niagra processors the shared fp units normally are a bottleneck for fp. But the larger problem was the register remapping/pipelines. They were fast, if you were running certain workloads. God help you if you had to compress anything on those systems. Without pbzip2 or pigz it took forever. Really bad example but bulldozer seemed way too niagraish to me based on its goals.
- AnthonyMouse 13y agoRunning threaded floating point workloads on bulldozer-derived architectures is just folly. If you have parallel floating point code you should in general be running it on a GPU.
- znowi 13y agoI think maybe AMD should move to niche markets and stop trying to compete with Intel, giving how vast the gap is in technology and resources.
- freehunter 13y agoIf there's no one trying to compete with Intel, I would guess that gap would close fairly quickly.
- TallGuyShort 13y agoIBM shipped a 5.2 GHz chip for it's mainframes over 2 years ago. This is not the first.
- CountHackulus 13y agoExactly, this is the first ever 5GHz x86 chip. The title is factually inaccurate.
- ignostic 13y agoThat's not surprising, given the title comes from and links to a press release.
- itcmcgrath 13y agoIndeed. We have a few zEnterprise systems in our corp data center (geeky enough looking that I want one in my basement), running with 5.5GHz chips. https://en.wikipedia.org/wiki/IBM_System_z https://en.wikipedia.org/wiki/IBM_System_z
- AnthonyMouse 13y agoThey didn't ship the first 64-bit CPU to run Windows either. Windows NT ran on Alpha (among other architectures). Granted the OS was still 32-bit, but the CPU wasn't. But what do you expect from a press release? It's written by marketing trolls, not engineers.
- marshray 13y agoAMD literally defined the 64-bit x86 architecture that everyone (including Intel) uses today. That's "first".
- ck2 13y agoI wonder how far they will OC on air.
- sigzero 13y agoI think there should be a "their" in there, somewhere.
- kayoone 13y agoI wonder how two of these (16 cores) compare against the new mac pro with the best CPU in software that benefits from many cores like 3D rendering and such or virtualization. Id bet they are close while the AMD only costs a fraction of the Xeon. I know its not a fair comparision since the FX-9000 is not a workstation cpu, but still...
- bluedino 13y agoThe multi-threaded Pov-Ray and Cinebench tests are just about the only two benchmarks where the AMD 8-cores beat the i7 2600k, and just barely beats it. The Intel chips soundly win in anything else (encoding, Photoshop...), and by almost 2X in some of the single-threaded tests.
- deepblueq 13y agoThe problem is that clock doesn't really mean anything concrete in terms of real world performance. It's strictly a marketing thing. For an example, what if a chip used a 10 GHz clock for distribution, and divided it down to 5 GHz everywhere it was actually used (not that I know of any reason to do such a thing besides marketing). Would it be marketable as a 10 GHz chip? The manufacturer would certainly be in hot water if enthusiasts ever found out... Even without such contrived scenarios, CPUs get different amounts of stuff done per clock. Something I keep seeing, even on Slashdot and Hacker News, is the idea that a CPU that has to clock higher for a given performance will use more power. It seems to me that if you've got double the clock, the likely explanation is that half the transistors are switching per clock, and power consumption should be orthogonal to clock/IPC ratio. If anyone's got any contrary ideas on that, I'd love to hear them. All I can think of is that higher clocks would correlate with longer pipelines, but bulldozer's pipeline isn't even that long.
- VLM 13y ago"is the idea that a CPU that has to clock higher for a given performance will use more power." This is like a dog whistle to the EEs, they're going to get all riled up by programmers with screwdrivers. You can model a stereotypical FET gate as a capacitor, all you're really doing is charging and discharging capacitors either in FET gates or the transmission line theoretical capacitance. Right out of the C=Q/V definition of what capacitance is, mushed up against some ohms law and some algebra, and you end up with P=C times V squared times F. So you can see the intense excitement in lowering core voltages, making gates and lines smaller (lowering C) all in a tradeoff to improve the P/F or F/P (whatever) ratio. The important part is its pretty easy, right outta ohms law and the def of what capacitance is, power is directly proportional to frequency.
- tbrownaw 13y agoThe important part is its pretty easy, right outta ohms law and the def of what capacitance is, power is directly proportional to frequency. There's also the fact that your transistors have a particular voltage that they switch state at, which means that they switch faster if you drive the gate/line capacitance with a higher voltage. Which means that chips designed for lower frequencies can be designed to use lower voltages, which can save far more power than what would be directly proportional to the lower frequency.
- ogdoad 13y agofinally, angry birds will be totally responsive!
- nvmc 13y agoI've been waiting since my Athlon64 died for AMD to make a chip worth getting. Them taking the brute force (P4) approach is not all that encouraging.
- yason 13y agoIn the end it's not the frequencies nor number of cores but performance per watt that matters. Most computers run on batteries these days, and those that don't drain ever more expensive electricity from the wall socket and at the same time waste a lot of it producing huge amounts of heat. The more you get out of a watt the better. You can either trade in speed for lower power or trade in power for better performance, but in either case you want the performance/watt ratio to be the highest. I would guess the power consumption of running the chip at 5GHz is pretty high. And running temperatures as well. And yet there are fewer and fewer of those huge tasks that you can only do with one core.
- makomk 13y agoProbably, though it's hard to get a good grasp on actual power efficiency because Intel fudge their power figures so much these days...
- sliverstorm 13y agoIn the end it's not the frequencies nor number of cores but performance per watt that matters. It depends on the workload, really. It should already be obvious that this part is not meant to be a Joe Everyman processor.
- scotty79 13y agoSince Pentium 133 I never had Intel processor in desktop computer. I wanted few times but AMD was always cheeper for the same speed. Sure fastest were almost always the Intel ones but the additional bit of speed never justified the price.
- csense 13y agoMy hyperthreaded [1] Core i7 makes kernel compile jobs fly. [1] http://en.wikipedia.org/wiki/Hyperthreading http://en.wikipedia.org/wiki/Hyperthreading
- scotty79 13y agoIt just splits core into sort of two virtual cores. I'm not sure how that could help. Have you check how disabling it influences compiling speed?
- csense 13y ago> I'm not sure how that could help Hyperthreading keeps two threads "hot" in each physical core. When one thread is waiting on memory access, the core can do work on the other thread rather than sitting idle. (Memory access isn't that slow, so switches need to be fast to capture those otherwise-wasted cycles, which is why this is a CPU hardware feature rather than an OS-level software feature.) Purely CPU-bound tasks [1] don't get any performance gains from HT. But almost all real-world applications spend a lot of time reading and writing memory, and memory access is pretty slow compared to CPU speeds, so in practice HT helps (otherwise Intel wouldn't have bothered to develop it and put it on their chips, which probably cost a lot of money). > Have you check how disabling it influences compiling speed? No. But I'd guess it would be substantially less than 100% speedup since they aren't actual, physical cores; but substantially more than 0% speedup since the compiler uses dozens or even low hundreds of megabytes of memory. [1] By "CPU-bound" I mean register-to-register arithmetic. You might also be able to get away with hitting the L1 cache, which is a few KB, without triggering an HT context switch.
- zmonkeyz 13y ago(for consumers)
- shawnz 13y agoHow ironic that AMD are now suffering from the same thing that once gave them the edge (that is, Pentium 4's overly aggressive clock speed roadmap and lacklustre per-clock efficiency).
- Pherdnut 13y agoYAYYY!!! Okaynowwhydothebenchmarkssuck.