If you carefully looked through the contents of BIOS Setup, then you may well have noticed the CPU Hyper Threading Technology option there. And you may have wondered what Hyper Threading is (or hyperthreading, the official name is Hyper Threading Technology, HTT), and what this option is for.

Hyper Threading is a relatively new technology developed by Intel for Pentium architecture processors. As practice has shown, the use of Hyper Threading technology has made it possible in many cases to increase CPU performance by approximately 20-30%.

Here you need to remember how a computer’s central processor generally works. As soon as you turn on the computer and run a program on it, the CPU begins to read the instructions contained in it, written in the so-called machine code. It reads each instruction in turn and executes them one after another.

However, many programs have several simultaneously running software processes. In addition, modern operating systems allow the user to have several programs running at once. And they don’t just allow it - in fact, a situation where a single process is running in the operating system is completely unthinkable today. Therefore, processors developed using older technologies had low performance in cases where it was necessary to process several simultaneous processes at once.

Of course, in order to solve this problem, you can include several processors or processors using several physical computing cores in the system. But such an improvement is expensive, technically complex and not always effective from a practical point of view.

Development history

Therefore, it was decided to create a technology that would allow processing multiple processes on one physical core. In this case, for programs, it will look outwardly as if there were several processor cores in the system at once.

Hyper Threading technology support first appeared in processors in 2002. These were processors of the Pentium 4 family and Xeon server processors with clock speeds above 2 GHz. Initially, the technology was codenamed Jackson, but then its name was changed to Hyper Threading, which is more understandable to the general public - which can be roughly translated as “super-threading”.

At the same time, according to Intel, the surface area of ​​​​the processor crystal that supports Hyper Threading has increased compared to the previous model that does not support it by only 5%, with an average performance increase of 20%.

Despite the fact that the technology has generally proven itself well, however, for a number of reasons, Intel decided to disable Hyper Threading technology in the Core 2 family processors that replaced the Pentium 4. Hyper Threading, however, later reappeared in processors of the Sandy Bridge and Ivy architectures Bridge and Haswell, having been significantly redesigned.

The essence of technology

Understanding Hyper Threading Technology is important because it is one of the key features in Intel processors.

Despite all the success that processors have achieved, they have one significant drawback - they can only execute one instruction at a time. Let's say that you launched applications such as a text editor, a browser and Skype at the same time. From the user's point of view, this software environment can be called multitasking, however, from the processor's point of view this is far from the case. The processor core will still execute one instruction per certain period of time. In this case, the task of the processor is to distribute processor time resources between individual applications. Because this sequential execution of instructions happens extremely quickly, you don't notice it. And it seems to you that there is no delay.

But there is still a delay. The delay occurs due to the way each program supplies the processor with data. Each data stream must arrive at a specific time and be processed individually by the processor. Hyper Threading technology makes it possible for each processor core to schedule data processing and distribute resources simultaneously for two threads.

It should be noted that in the core of modern processors there are several so-called execution devices, each of which is designed to perform a specific operation on data. In this case, some of these executive devices may be idle while processing data from one thread.

To understand this situation, we can give an analogy with workers working in an assembly shop on a conveyor and processing different types of parts. Each worker is equipped with a specific tool designed to perform a task. However, if parts arrive in the wrong sequence, delays occur because some workers wait in line to start work. Hyper Threading can be compared to an additional conveyor belt that was laid in the workshop so that previously idle workers would carry out their operations independently of others. The workshop is still one, but parts are processed more quickly and efficiently, resulting in reduced downtime. Thus, Hyper Threading made it possible to turn on those processor execution units that were idle while executing instructions from one thread.

As soon as you turn on a computer with a dual-core processor that supports Hyper Threading and open Windows Task Manager under the Performance tab, you will find four graphs in it. But this does not mean that you actually have 4 processor cores.

This happens because Windows thinks that each core has two logical processors. The term "logical processor" sounds funny, but it means a processor that doesn't physically exist. Windows can send streams of data to each logical processor, but only one core actually does the work. Therefore, a single core with Hyper Threading technology is significantly different from separate physical cores.

Hyper Threading technology requires support from the following hardware and software:

• CPU
• Motherboard chipset
• operating system

Benefits of technology

Now let's consider the following question: how much does Hyper Threading technology increase computer performance? In everyday tasks, such as surfing the Internet and typing, the benefits of technology are not so obvious. However, keep in mind that today's processors are so powerful that everyday tasks rarely fully utilize the processor. In addition, a lot also depends on how the software is written. You may have multiple programs running at once, but if you look at the load graph, you will see that only one logical processor per core is being used. This happens because the software does not support the distribution of processes between cores.

However, for more complex tasks, Hyper Threading can be more useful. Applications such as 3D modeling programs, 3D games, music or video encoding/decoding programs, and many scientific applications are written to take full advantage of multithreading. So you can experience the performance benefits of a Hyper Threading-enabled computer while playing challenging games, listening to music, or watching movies. The performance increase can reach up to 30%, although there may be situations where Hyper Threading does not provide an advantage at all. Sometimes, if both threads load all processor execution units with the same tasks, a slight decrease in performance may even be observed.

Returning to the presence of a corresponding option in BIOS Setup that allows you to set Hyper Threading parameters, in most cases it is recommended to enable this function. However, you can always disable it if it turns out that your computer is running with errors or even has lower performance than you expected.

Conclusion

Since the maximum performance increase when using Hyper Threading is 30%, it cannot be said that the technology is equivalent to doubling the number of processor cores. However, Hyper Threading is a useful option, and as a computer owner, it will not hurt you. Its benefit is especially noticeable when, for example, you edit multimedia files or use your computer as a workstation for professional programs such as Photoshop or Maya.

15.03.2013

Hyper-Threading technology appeared in Intel processors, scary to say, more than 10 years ago. And at the moment it is an important element of Core processors. However, the question of the need for HT in games is still not completely clear. We decided to conduct a test to understand whether gamers need a Core i7, or if a Core i5 is better. And also find out how much better Core i3 is than Pentium.

Hyper-Threading Technology, developed by Intel and exclusively used in the company's processors, starting with the memorable Pentium 4, is something that is taken for granted at the moment. A significant number of processors of current and previous generations are equipped with it. It will be used in the near future.

And it must be admitted that Hyper-Threading technology is useful and has a positive effect on performance, otherwise Intel would not use it to position its processors within the line. And not as a secondary element, but one of the most important, if not the most important. To make it clear what we are talking about, we have prepared a table that makes it easy to evaluate the principle of segmentation of Intel processors.

As you can see, there are very few differences between the Pentium and Core i3, as well as between the Core i5 and Core i7. In fact, the i3 and i7 models differ from the Pentium and i5 only in the size of the third level cache per core (not counting the clock frequency, of course). The first pair has 1.5 megabytes, and the second pair has 2 megabytes. This difference cannot fundamentally affect the performance of processors, since the difference in cache size is very small. That is why Core i3 and Core i7 received support for Hyper-Threading technology, which is the main element that allows these processors to have a performance advantage over Pentium and Core i5, respectively.

As a result, a slightly larger cache and Hyper-Threading support will allow significantly higher prices for processors. For example, processors of the Pentium line (about 10 thousand tenge) are approximately two times cheaper than Core i3 (about 20 thousand tenge), and this despite the fact that physically, at the hardware level, they are absolutely identical, and, accordingly, have the same cost . The price difference between Core i5 (about 30 thousand tenge) and Core i7 (about 50 thousand tenge) is also very large, although less than two times in younger models.

How justified is this increase in price? What real gain does Hyper-Threading provide? The answer has long been known: the increase varies, it all depends on the application and its optimization. We decided to check what HT can do in games, as one of the most demanding “household” applications. In addition, this test will be an excellent addition to our previous material on the effect of the number of cores in the processor on gaming performance.

Before moving on to the tests, let's remember (or find out) what Hyper-Threading Technology is. As Intel itself said when introducing this technology many years ago, there is nothing particularly complicated about it. In fact, all that is needed to introduce HT at the physical level is to add not one set of registers and an interrupt controller to one physical core, but two. In Pentium 4 processors, these additional elements increased the number of transistors by only five percent. In modern Ivy Bridge cores (as well as Sandy Bridge and future Haswell), the additional elements for even four cores do not increase the die by even 1 percent.

Additional registers and an interrupt controller, coupled with software support, allow the operating system to see not one physical core, but two logical ones. At the same time, the processing of data from two streams that are sent by the system still occurs on the same core, but with some features. One thread still has the entire processor at its disposal, but as soon as some CPU blocks are freed and idle, they are immediately given to the second thread. Thanks to this, it was possible to use all processor blocks simultaneously, and thereby increase its efficiency. As Intel itself stated, the performance increase under ideal conditions can reach up to 30 percent. True, these indicators are true only for the Pentium 4 with its very long pipeline; modern processors benefit from HT less.

But ideal conditions for Hyper-Threading are not always the case. And most importantly, the worst result of HT is not the lack of performance gain, but its decrease. That is, under certain conditions, the performance of a processor with HT will drop relative to a processor without HT due to the fact that the overhead costs of dividing threads and organizing a queue will significantly exceed the gain from calculating parallel threads, which is possible in this particular case. And such cases occur much more often than Intel would like. Moreover, many years of using Hyper-Threading have not improved the situation. This is especially true for games that are very complex and not at all standard in terms of data calculation and applications.

In order to find out the impact of Hyper-Threading on gaming performance, we again used our long-suffering Core i7-2700K test processor, and simulated four processors at once by disabling cores and turning HT on/off. Conventionally, they can be called Pentium (2 cores, HT disabled), Core i3 (2 cores, HT enabled), Core i5 (4 cores, HT disabled), and Core i7 (4 cores, HT enabled). Why conditional? First of all, because according to some characteristics they do not correspond to real products. In particular, disabling cores does not lead to a corresponding reduction in the volume of the third level cache - its volume for all is 8 megabytes. And, in addition, all our “conditional” processors operate at the same frequency of 3.5 gigahertz, which has not yet been achieved by all processors in the Intel line.

However, this is even for the better, since thanks to the constant change of all important parameters, we will be able to find out the real impact of Hyper-Threading on gaming performance without any reservations. And the percentage difference in performance between our “conditional” Pentium and Core i3 will be close to the difference between real processors, provided the frequencies are equal. It should also not be confusing that we are using a processor with Sandy Bridge architecture, since our efficiency tests, which you can read about in the article “Bare Performance - Examining the Efficiency of ALUs and FPUs,” showed that the influence of Hyper-Threading in the latest generations of processors Core remains unchanged. Most likely, this material will also be relevant for upcoming Haswell processors.

Well, it seems that all the questions regarding the testing methodology, as well as the operating features of Hyper-Threading Technology, have been discussed, and therefore it’s time to move on to the most interesting thing - the tests.

Even in a test in which we studied the impact of the number of processor cores on gaming performance, we found that 3DMark 11 is completely relaxed about CPU performance, working perfectly even on one core. Hyper-Threading had the same “powerful” influence. As you can see, the test does not notice any differences between Pentium and Core i7, not to mention intermediate models.

Metro 2033

But Metro 2033 clearly noticed the appearance of Hyper-Threading. And she reacted negatively to him! Yes, that's right: enabling HT in this game has a negative impact on performance. A small impact, of course - 0.5 frames per second with four physical cores, and 0.7 with two. But this fact gives every reason to say that the Metro 2033 Pentium is faster than the Core i3, and the Core i5 is better than the Core i7. This is confirmation of the fact that Hyper-Threading does not show its effectiveness always and not everywhere.

Crysis 2

This game showed very interesting results. First of all, we note that the influence of Hyper-Threading is clearly visible in dual-core processors - the Core i3 is ahead of the Pentium by almost 9 percent, which is quite a lot for this game. Victory for HT and Intel? Not really, since the Core i7 did not show any gain relative to the noticeably cheaper Core i5. But there is a reasonable explanation for this - Crysis 2 cannot use more than four data streams. Because of this, we see a good increase in the dual-core with HT - still, four threads, albeit logical, are better than two. On the other hand, there was nowhere to put additional Core i7 threads; four physical cores were quite enough. So, based on the results of this test, we can note the positive impact of HT in the Core i3, which is noticeably better than the Pentium here. But among quad-core processors, the Core i5 again looks like a more reasonable solution.

Battlefield 3

The results here are very strange. If in the test for the number of cores, battlefield was an example of a microscopic but linear increase, then the inclusion of Hyper-Threading introduced chaos into the results. In fact, we can state that the Core i3, with its two cores and HT, turned out to be the best of all, ahead of even the Core i5 and Core i7. It’s strange, of course, but at the same time, Core i5 and Core i7 were again on the same level. What explains this is not clear. Most likely, the testing methodology in this game played a role here, which gives greater errors than standard benchmarks.

In the last test, F1 2011 proved to be one of the games that is very critical of the number of cores, and in this test it again surprised us with the excellent impact of Hyper-Threading technology on the performance. And again, as in Crysis 2, the inclusion of HT worked very well on dual-core processors. Look at the difference between our conditional Core i3 and Pentium - it is more than twofold! It is clearly visible that the game is very much lacking two cores, and at the same time its code is parallelized so well that the effect is amazing. On the other hand, you can’t argue with four physical cores - Core i5 is noticeably faster than Core i3. But the Core i7, again, as in previous games, did not show anything outstanding compared to the Core i5. The reason is the same - the game cannot use more than 4 threads, and the overhead of running HT reduces the performance of the Core i7 below the level of the Core i5.

An old warrior needs Hyper-Threading no more than a hedgehog needs a T-shirt - its influence is by no means as clearly noticeable as in F1 2011 or Crysis 2. However, we still note that turning on HT on a dual-core processor brought 1 extra frame. This is certainly not enough to say that Core i3 is better than Pentium. At the very least, this improvement clearly does not correspond to the difference in price of these processors. And it’s not even worth mentioning the price difference between Core i5 and Core i7, since the processor without HT support again turned out to be faster. And noticeably faster - by 7 percent. Whatever one may say, we again state the fact that four threads is the maximum for this game, and therefore HyperThreading in this case does not help the Core i7, but hinders.

Hyper-Threading technology (HT, hyperthreading) first appeared 15 years ago - in 2002, in Pentium 4 and Xeon processors, and since then has appeared in Intel processors (in the Core i line, some Atom, and recently also in Pentium), then disappeared (its support was not in the Core 2 Duo and Quad lines). And during this time it has acquired mythical properties - they say its presence almost doubles the processor performance, turning weak i3s into powerful i5s. At the same time, others say that HT is a common marketing ploy and is of little use. The truth is, as usual, in the middle - in some places there is some sense from it, but you definitely shouldn’t expect a two-fold increase.

Technical description of the technology

Let's start with the definition given on the Intel website:

Intel® Hyper-Threading Technology (Intel® HT) enables more efficient use of processor resources by allowing multiple threads to run on each core. In terms of performance, this technology increases the throughput of processors, improving the overall performance of multi-threaded applications.

In general, it is clear that nothing is clear - just general phrases, but they briefly describe the technology - HT allows one physical core to simultaneously process several (usually two) logical threads. But how? Processor supporting hyperthreading:

• can store information about several running threads at once;
• contains one set of registers (that is, fast memory blocks inside the processor) and one interrupt controller (that is, a built-in processor unit responsible for the ability to sequentially process requests for the occurrence of any event that requires immediate attention from different devices) for each logical CPU.

Let's look at a simple example:

Let's say the processor has two tasks. If the processor has one core, then it will execute them sequentially, if two, then in parallel on two cores, and the execution time of both tasks will be equal to the time spent on the heavier task. But what if the processor is single-core, but supports hyperthreading? As you can see in the picture above, when performing one task, the processor is not 100% busy - some processor blocks are simply not needed in this task, somewhere the branch prediction module is making an error (which is needed to predict whether a conditional branch will be executed in the program), somewhere there is a cache access error - in general, when executing a task, the processor is rarely more than 70% busy. And the HT technology just “shoves” a second task into unoccupied processor blocks, and it turns out that two tasks are processed simultaneously on one core. However, doubling performance does not happen for obvious reasons - very often it turns out that two tasks need the same computing unit in the processor, and then we see a simple one: while one task is being processed, the execution of the second one simply stops at this time (blue squares - the first task, green - second, red - tasks accessing the same block in the processor):

As a result, the time spent by a processor with HT on two tasks turns out to be more than the time required to calculate the heaviest task, but less than the time required to sequentially evaluate both tasks.

Pros and cons of technology

Taking into account the fact that the processor die with HT support is physically larger than the processor die without HT by an average of 5% (this is how much additional register blocks and interrupt controllers take up), and HT support allows you to load the processor by 90-95%, then compared to 70 % without HT we get that the increase at best will be 20-30% - the figure is quite large.

However, not everything is so good: it happens that there is no performance gain from HT at all, and it even happens that HT worsens the performance of the processor. This happens for many reasons:

• Lack of cache memory. For example, modern quad-core i5s have 6 MB of L3 cache - 1.5 MB per core. In quad-core i7s with HT, the cache is already 8 MB, but since there are 8 logical cores, we get only 1 MB per core - during calculations, some programs may not have enough of this volume, which leads to a drop in performance.
• Lack of software optimization. The most basic problem is that programs consider logical cores to be physical, which is why when executing tasks in parallel on one core, delays often occur due to tasks accessing the same computational unit, which ultimately reduces the performance gain from HT to nothing.
• Data dependency. It follows from the previous point - to complete one task, the result of another is required, but it has not yet been completed. And again we get downtime, a reduction in CPU load and a small increase from HT.

Programs that can work with hyperthreading

There are many of them, because for HT computing this is manna from heaven - heat dissipation practically does not increase, the processor does not become much larger, and with proper optimization you can get an increase of up to 30%. Therefore, its support was quickly implemented in those programs where it is easy to parallelize the load - in archivers (WinRar), programs for 2D/3D modeling (3ds Max, Maya), programs for photo and video processing (Sony Vegas, Photoshop, Corel Draw) .

Programs that do not work well with hyperthreading

Traditionally, this is the majority of games - they are usually difficult to parallelize competently, so often four physical cores at high frequencies (i5 K-series) are more than enough for games, parallelizing which with 8 logical cores in i7 turns out to be an impossible task. However, it is also worth considering that there are background processes, and if the processor does not support HT, then their processing falls on the physical cores, which can slow down the game. Here the i7 with HT wins - all background tasks traditionally have a lower priority, so when running simultaneously on one physical core of the game and a background task, the game will receive increased priority, and the background task will not “distract” the cores busy with the game - that’s why For streaming or recording games, it is better to take an i7 with hyperthreading.

Results

Perhaps there is only one question left here - does it make sense to take processors with HT or not? If you like to keep five programs open at the same time and play games at the same time, or are engaged in photo processing, video or modeling - yes, of course it’s worth taking. And if you are used to closing all others before launching a heavy program, and do not dabble in processing or modeling, then a processor with HT is of no use to you.

One of the most important elements in the positioning of processors Intel inside the rulers, is the technology Hyper-Threading. Or rather, its absence in the processor, or its presence. What is this technology responsible for? Intel Hyper-Threading, is a technology for efficient use of processor core (CPU) resources, allowing multiple threads to be processed simultaneously on a single core.

Let's try to give an example of a similar system from life. Imagine a border post with control of every car, many customs officers and one access lane for cars. A traffic jam accumulates and the process slows down on its own, even regardless of the speed of the employees’ work. And given that there is only one lane, half of the employees are simply bored. And then suddenly another lane is opened for vehicles and cars begin to approach in two streams. The speed of work increases, free employees begin to work, and the traffic jam of those wishing to cross the border becomes significantly smaller. As a result, without increasing the size of customs and the number of employees, the throughput and efficiency of one post increased.

Even the most powerful processor core must receive information without delay in order to process it quickly. As soon as a “traffic jam” of data forms at the input, the processor begins to idle, waiting for this or that information to be processed.

To avoid this, technology appeared back in 2002 Hyper-Threading, which simulated the appearance of a second core in the system, thanks to which the core capacity was filled more quickly.

As practice has shown, few people know how the technology actually works Intel Hyper-Threading. Most people are sure that they simply have several additional virtual cores living in their processor. But in fact, the number of cores does not change, it is the number of threads that changes, and this is critically important. It’s just that each core has an additional input/output channel. Below is a video of how it actually works.

How does HT technology work, and where do additional streams come from? In fact, everything is quite simple. To implement this technology, one controller and a set of registers are added to each core. Thus, as soon as the data flow becomes greater than the capacity of one channel, a second channel is connected. Thus, idle time of unused processor blocks is eliminated.

In the era of single-core processors (Intel Pentium 4), HT technology became a salvation for those who could not buy a more expensive processor (Pentium D). But today there are known cases of decreased performance when HT is activated. Why is this happening? It's quite simple. Parallelizing data and properly processing the process also requires some processor power. And as soon as there are enough physical cores to process information without idle blocks, performance decreases slightly due to the resources selected by the HT technology. Therefore, the worst case scenario for Hyper-Threading is not a lack of performance increase, but a decrease in performance. But in practice this happens very rarely.

With the release of the eight thousandth line of Intel Core processors, this question has become especially relevant - is it necessary? Hyper-Threading at all? After all, even Core i5 processors have full six cores. If we don’t talk about professional applications for graphics processing, rendering, etc., then there is a possibility that six physical cores will be enough for all office applications and games. Therefore, if it was initially believed that HT technology adds up to 30% performance to the processor, now this is not an axiom, and everything will depend on your style of working at the computer and the set of utilities you use.

Of course, the text would be incomplete without testing. Therefore, we will take the processors we have Intel Core i7 8700K And 7700K, and check the performance of processors with activated Hyper-Threading, and deactivated. Based on the results of testing, it will become clear in which applications virtual cores add performance, and in which they remain unnoticed.

The popular 3DMark does not respond particularly readily to the increase in cores and threads. There is an increase, but it is insignificant.

In various types of calculations and processing, kernels and threads have always ruled. Here Hyper-Threading is simply necessary; it greatly increases performance.

In games the situation is simpler. In most cases, increasing the number of threads does not produce results, i.e. For games, 4 physical cores are enough, and in most cases, even less. The only exception was GTA5, which responded very well to disabling HT and added 7% performance, and only on a six-core 8700K processor. Disabling multithreading on the 7700K did not give any results. We ran the benchmarks several times and the results were unchanged. But this is rather an exception to the rule. All tested games are easily satisfied with four cores.

One of the most important elements in the positioning of Intel processors within lines is Hyper-Threading technology. Or rather, its absence in the processor, or its presence. What is this technology responsible for? Intel Hyper-Threading is a technology for efficiently using the resources of processor cores (CPU), allowing simultaneous processing of multiple threads on one core. Let's try to give an example of a similar system from life. Imagine a border post with control of every car, many customs officers and one access lane for cars. A traffic jam accumulates and the process slows down on its own, even regardless of the speed of the employees’ work. And given that there is only one lane, half of the employees are simply bored. And then suddenly another lane is opened for vehicles and cars begin to approach in two streams. The speed of work increases, free employees begin to work, and the traffic jam of those wishing to cross the border becomes significantly smaller. As a result, without increasing the size of customs and the number of employees, the throughput and efficiency of one post increased. Even the most powerful processor core must receive information without delay in order to process it quickly. As soon as a “traffic jam” of data forms at the input, the processor begins to idle, waiting for this or that information to be processed. To avoid this, back in 2002, Hyper-Threading technology appeared, which simulated the appearance of a second core in the system, thanks to which the core capacity was filled more quickly. As practice has shown, few people know how Intel Hyper-Threading technology actually works. Most people are sure that they simply have several additional virtual cores living in their processor. But in fact, the number of cores does not change, it is the number of threads that changes, and this is critically important. It’s just that each core has an additional input/output channel. Below is a video of how it actually works. How does HT technology work, and where do additional streams come from? In fact, everything is quite simple. To implement this technology, one controller and a set of registers are added to each core. Thus, as soon as the data flow becomes greater than the capacity of one channel, a second channel is connected. Thus, idle time of unused processor blocks is eliminated. In the era of single-core processors (Intel Pentium 4), HT technology became a salvation for those who could not buy a more expensive processor (Pentium D). But today there are known cases of decreased performance when HT is activated. Why is this happening? It's quite simple. Parallelizing data and properly processing the process also requires some processor power. And as soon as there are enough physical cores to process information without idle blocks, performance decreases slightly due to the resources selected by the HT technology. Therefore, the worst case scenario for Hyper-Threading is not a lack of performance increase, but a decrease in performance. But in practice this happens very rarely. With the release of the eight thousandth line of Intel Core processors, this question has become especially relevant - is Hyper-Threading needed at all? After all, even Core i5 processors have full six cores. If we don’t talk about professional applications for graphics processing, rendering, etc., then there is a possibility that six physical cores will be enough for all office applications and games. Therefore, if it was initially believed that HT technology adds up to 30% performance to the processor, now this is not an axiom, and everything will depend on your style of working at the computer and the set of utilities you use. Of course, the text would be...