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What is Processor Cache?

There are various terms you might have heard as well as read with regards to some type of computer device. Certainly there are several you have no idea what they mean. This article is planning to talk about the query 'what is cache memory?' You probably have often heard this before in relation to your internet browser when someone informs you to clear your cache.

The cache memory on a computer system is usually a tiny part of random access memory also called RAM that has been allocated to keep operations that happen to be carried out often. This element helps to speed up these types of processes as it does not have to search through the personal computer, making these kinds of actions operate faster.

Of course the more cache memory you have the faster your platform is going to run. By using much more of this memory you are able to store additional information. Nowadays the standard personal computer system comes with far more as compared to in years past.

Allow us to present additional technical terms and information as we continue the article on cache memory explained. This kind of memory is certainly termed SDRAM that is known as high speed static memory. It is much quicker than the DRAM that is the system's principal memory.
   
A lot of CPUs actually have something termed Level I (L1) ram memory built in them; they are usually from 8kb to 16kb and also used on Intel and Pentium processor chips. Newer computers normally will not have L1 cache memory, but rather have Level 2 (L2). L2 is in fact cache memory stored externally between processor chip and the specific DRAM.

Now in making points a little bit more complicated we can include on top of this that there is also a Level 3 (L3) cache memory. This circumstance is when the computer system has L1 and L2 constructed into the CPU processor and has an external chip that makes it L3.

You will also take note there is something termed disk cache. This is the portion of system RAM and is slower compared to the L1, L2 and L3. This can be used to read and write to the specific hard disk and is typically run by means of some type of software.

Finally there is something named peripheral cache memory. That is normally for a cd-rom drive as well as dvd-drive; it truly is much slower in contrast to L1, L2 and L3 and slower compared to the hard drive cache. That being said, these will be cached to the hard disk.

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Multi-core Architectures: Heterogeneous processors

INTRODUCTION: A heterogeneous processor integrates a mix of "big" and "small" cores, and thus can potentially achieve the benefits of both. Several usages motivate this design:

Parallel processing: with a few big and many small cores, the processor can deliver higher performance at possibly the same or lower power than an iso-area homogeneous design. 

Power savings: the processor uses small cores to save power. For example, it can operate in two modes: a high-power mode in which all cores are available and a low power mode in which applications only run on the small cores to save power at the cost of performance.

Accelerator: unlike the previous models, where the big cores have higher performance and even more features, in this model, the small cores implement special instructions, such as vector processing, which are unavailable on the big cores. Thus, applications can use the small cores as accelerators for these operations.

Heterogeneous Architectures:

(1)Design Space: We classify heterogeneous architectures into two types: performance asymmetry and functional asymmetry. The former refers to architectures where cores differ in performance (and power) due to different clock speeds, cache sizes, microarchitectures, and so forth. Applications run correctly on any core, but can have different performance.

(2)OS Challenges: there are two sets of challenges:

Correctness: OSes typically query processor features on the bootstrap processor (BSP) and assume the same for every core. This assumption becomes invalid for heterogeneous
processors. With instruction-based asymmetry, software can fail on one core but succeed on another. This needs to be handled properly to ensure correct execution.

Performance:Even when software runs correctly, obtaining high performance can be challenging. With performance asymmetry, an immediate challenge is how applications can share the high-performance cores fairly, especially when they belong to different users. OS scheduling should also enable consistent application performance across different

runs. Otherwise, a thread may execute on a fast core in one run but a slow one in another, causing performance variations. Scheduling is further complicated as threads can perform differently on different cores. In general, one would expect higher performance on a faster core; however,for I/O-bound applications, this may not be true. Choosing the right thread-to-core mappings can be challenging.

Supporting Performance Asymmetry

Quantifying CPU Performance: An essential component of our algorithms is to assign a
performance rating per CPU such that we can estimate performance differences if a thread is to run on different CPUs.There are various ways to obtain CPU ratings. Our design allows the OS to run a simple benchmark of its choice at boot time and set a default rating for each CPU. When the system is up, the OS or user can run complex benchmarks such as SPEC CPU* to override the default ratings if desired. The processor manufacturer can also provide CPU ratings, which the OS can use as the default. All of these approaches produce the same result, i.e., a static rating per CPU. If the rating of a CPU is X times higher than the rating of another CPU, we say this CPU is X times faster.

Faster-First Scheduling: If two CPUs are idle and a thread can run on both of them, we always run it on the faster CPU. The algorithm consists of two components:

Initial placement: When scheduling a thread for the first time after its creation, if two CPUs are idle, we always choose the faster one to run it. If none is idle, our algorithm has no effect and the OS performs its normal action,typically selecting the most lightly loaded CPU.

Dynamic migration: During execution, a faster CPU can become idle. If any thread is running on a slow CPU, we preempt it and move it to the faster CPU. Thus, if the total
number of threads is less than or equal to the number of faster CPUs, every thread can run on a faster CPU and achieve maximum performance.

Instruction-based Asymmetry :To emulate the accelerator usage model in Section 1, we
configure the small cores with a 2 GHz frequency, resulting in a 32% lower SPEC CPU2006* rating than the big cores.

Fault-and-migrate performance: We perform three experiments for the three instruction-asymmetry benchmarks.First, we run the non-SSE4.1 version by pinning it on a big core, which gives the performance of running on a homogeneous system of big cores without SSE4.1. Second, we run the SSE4.1 version without pinning. With faster-first scheduling, it starts on a big core; on an SSE4.1 instruction,it faults and migrates to a small core and later back to a big core. Thus, the benchmark migrates back and forth between the big and small cores, allowing us to evaluate overheads of fault-and-migrate. To evaluate the impact of T, we repeat this experiment with T equal to 1, 2, 4, and 8, where one tick in our system is 4 ms. Finally, to emulate a costly design of homogeneous big cores with SSE4.1, we  re-configure each small core to have equivalent performance to the big core. By pinning the SSE4.1 version of each benchmark to this core, we get an upper bound for any heterogeneous configuration with fault-and-migrate.

Conclusion :Heterogeneous architectures provide a cost-effective solution for improving both single-thread performance and multi-thread throughput. However, they also face significant challenges in the OS design, which traditionally assumes only homogeneous hardware. This paper presents a set of algorithms that allow the OS to effectively manage heterogeneous CPUs.

Our fault-and-migrate algorithm enables the OS to transparently support instruction-based asymmetry. Faster-first scheduling improves application performance by allowing them to utilize faster cores whenever possible. Finally, DWRR allows applications to fairly share CPU resources, enabling good individual application performance and system throughput. We have implemented these algorithms in Linux 2.6.24 and evaluated them on an actual heterogeneous platform. Our results demonstrated
that, with incremental changes, we can modify an existing OS to effectively manage heterogeneous hardware and achieve high performance for a wide range of applications.

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Computer Servers for Dummies

Servers are defined as computers that are configured in such a way that they are able to provide specialized services to a specific client user or machine. They serve as task masters that manage a variety of services such as files, system jobs, network requests, and other various processes. Although they can be used for a myriad of purposes, servers primarily function as web hosting solutions.

The Wonder of Web Servers

Servers have become a very versatile solution for a variety of user needs. May it be file storage management, a network firewall, an email server, or simply as a web hosting solution, servers are the answer to almost every need. In fact, it would be very difficult to find any type of contemporary business or company that does not make use of some sort of server.

One of the biggest misconceptions about web servers is that they might be too complicated for the average Joe. The truth is, they are quite simple to manage and so long as a user has some level of technical knowledge, he should be good to go. In fact, setting up a server for one’s own website isn’t too much of a daunting task. Although it will still require a certain level of computer know-how, it is no Herculean feat at all. With a little research, some patience, and a whole lot of resourcefulness, one could very easily set up a personal server for one’s own site. This is also made possible by the fact that most server providers equip their users with easy-to-use tools to make the entire process much more user-friendly.

.The Basics Types of Web Servers

When it comes to the configuration of web hosting servers, they generally come in three different offerings. First is shared web hosting which is the most common type of web server today. This immense fame is brought about by both its affordability and simplicity. Websites that run on shared servers will (obviously) share the same IP address as well as make use of the same system resources.

The second web hosting option for users is dedicated servers. As its name implies, websites that make use of a dedicated server will have full rights and control of the whole system. Because of the fact that they do not share their servers with other websites, this also means that they will have exclusive access to all the resources of the system.

The Keys to Success

Because of websites’ growing need for more hard drive storage space and bandwidth, servers have become more and more of a requirement rather than an option. Each individual or business will have a different set of requirements and needs which means there is no one-size-fits-all sort of web hosting solution for everyone. However, the good thing is that it isn’t that difficult to set up a specific type of server that will fulfil the needs of one’s own website. Doing a little online research will definitely be helpful in this regard as there are a multitude of websites that provide information and tips on how to set up a server for all sorts of business website.

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Motherboard Essentials Explained!

Motherboard is the foremost computer part that you should consider when assembling a PC. It is popularly called the heart of the computer since all components are connected to it. Basically, it relays information from and to all components. So when you assemble a PC, buy the motherboard first.

Buying a motherboard can be easy and convenient since they are already sold at a motherboard online store. All you have to do is list all your motherboard requirements and conveniently shop at a motherboard online store. If you're unsure of your motherboard requirements, below is a rundown of the usual requirements.

1. Size. A motherboard is available in different sizes. If you are buying a motherboard to replace an old defective one, then be sure that you buy the same size as your old one; your motherboard may not fit inside your existing computer case. But if you are buying a motherboard for a new assembly, then the size factor will depend on the components that you wish to install.

2. Processor Type and Socket. The motherboard socket is where the processor is plugged-in. It used to be that processors such as Intel and AMD were able to share the same socket. But now, after a few years of improving processors, each brand of processor has its own socket type determined by the number of pins on it. Basically, you won't be able to transfer from one brand of processor to another without replacing the motherboard as well. Even though replacing motherboard can be easy through a motherboard online store, the price tag can always cause a pinch. So if you want to avoid the unnecessary expenses of replacing a non-defective motherboard, carefully choose a processor that will match your CPU needs and use.
 
3. CPU components. The CPU components that should be specifically considered when buying a motherboard are: hard drive, memory and power supply. Memory cards are continually advancing and as they advance, their sockets advance drastically as well. The DDR for instance, the most commonly used memory card has 184 pins while the newly released DDR-2 has 240 pins. In the memory card market, the older version is usually phased out when a new version is released. So naturally, when your older version of memory card needs replacement, you may also need to replace the motherboard. This can be very frustrating especially if your motherboard does not have any defects. Therefore, to avoid being in this kind of situation, buy a motherboard that is compatible with the recent memory card versions.

The hard drive has more or less a similar story with memory cards. There are two types of hard drives available in the market: ATA and SATA, ATA being the older version and SATA the recent version. Recent versions of motherboards support both types but there are already quite a number that support only SATA. Manufacturers of the latter type may be anticipating an ATA phase out, so you may want to go with their anticipation. But just to be on the safe side, buy a motherboard that supports both HD types.

As CPU components advance, their power supply requirements advance as well. The typical motherboard power supply pins are in 20s and 24s. Moreover, newly launched processors, such as those from Intel and AMD, have separate power supply pins to support their high clock speed. So when you buy a motherboard for a new CPU assembly, consider the power supply requirements of your components.

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Computer processors (also called CPU) are the most important part in the computer at all. It controls the overall remaining components of the computer such as the mouse, keyboard, monitors, and others. The processor is an electronic circuit that executes computer programs. It does in four basic phases:

1. Fetch: in this phase, the processor collects the bytes to execute from memory (which may be RAM or cache). Each instruction is saved in memory as one or more bytes called word. The more the word length, the more complexity and power consumption of the processor. Once the processor collects the bytes, then it is ready to decode it.

2. Decoding: In this phase, the processor takes the bytes read in the previous step and input them to the decoder. The decoder activates then the line corresponding to the instruction whose bytes equal to the bytes read from the fetching phase. Each instruction in the processor is mapped to a certain bits or bytes by the designer so that when the processor fetches these bits or bytes, it can understand them. The number of bits used to represent each instruction may vary according to the processor type. Note that this number of bits may not take the whole word in the memory. For example if the word is represented by 8 bits, then the first four bits can be assigned to the instruction part and the last four bits can be assigned to the data which is needed for the instruction to execute.

3. Executing: once the processor knows the meaning of the bits by the decoder, it goes then to the execute phase. In this phase, the processor makes the necessary operation as denoted by the decoder. This operation is done on the operand contained along with the instruction bits in the memory word.. The operation can be addition, subtraction, AND, or any mathematical or logical operation.

4. Write Back: once the processor done the operation, it writes it back to the memory in the place denoted by the instruction. This result may be fed to other instructions in the same program.

This processes repeated for each instruction until the whole program is executed!

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Spyware is a type of malware but it is distinctively different from the regular computer viruses and hence they are not detected by the regular anti virus software. So, you need specifically designed anti spyware software to successfully remove the spywares.

Every computer and internet user needs to have a little knowledge about spyware and other malicious software. As these programs have the reputation of being quite dangerous for your computer, so it is better you take very good care of it and go for free spyware removers. This malicious stuff can create havoc to your pc, if proper step is not taken on the time, various big corporate houses, banks and other companies and lot of time and money for spyware protection.

Spyware can be installed on your computer without your knowledge, and can result in a number of computer performance issues. Spyware is designed to monitor or control your computer use. It can be used to monitor your web surfing, redirect your browser to particular websites, send pop-up ads, or record your keystrokes, which can ultimately lead to identity theft.

A virus-infected computer coupled with spyware is a very real security threat and the situation should be resolved immediately and decisively. It is good strategy to tackle the problem in a two-pronged manner. First, it is necessary to get a good anti-virus software tool that can scan your computer, detect and remove infected files.

Free Spyware removers are all over the internet, and because of the mechanics of demand and supply, their needs status have just increased ten fold over the past few years. Spyware is a big problem on the internet and the funny thing is, over 90% of people using computers at this very moment do not even know that their computer is being chocked, drawn and quartered by malicious software that is slowly eating away at system resources.

The best way to combat large inter-connected systems is to install windows anti spyware software in each workstation. This will help ease the jamming of networks etc. Many anti spyware companies of course offer free scan and free spyware remover programs. There are several thousands of these on the Internet. Many of these programs function similarly to anti-virus software.

It is also recommended that users run periodic scans to ensure that no harmful files have escaped detection. In addition, it should be kept in mind that free anti spyware or spyware removal programs do not offer antivirus protection, and a separate antivirus program is necessary if you opt for a free spyware removal program.

When choosing a free spyware scanner, make a research about it that will make you choose which of the different software will give you more benefits. Also consider knowing the security and website's legitimacy so you can't be fool by many bad guys who offers free tools over the internet. A free spyware scan will make your browsing a lot better.

Many people searching for an anti virus and spyware removal also searched online for anti virus protection a vast, anti virus software review, and even an antivirus software list.
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Introduction to the Motherboard

Take a look at the back of your desktop computer. All of the interface options available on the back of the machine are provided by a motherboard's back panel connector. The back panel houses typical connections like USB, Ethernet, Audio I/O, etc. The back panel position of motherboards is most often standardized to allow compatibility among various makes and models of cases, as the motherboard's back panel is secured to the case to provide stationary interface options.

Processor Socket

The processor socket is the portion of the motherboard which allows for a connection between the motherboard and the socket. Oftentimes, the socket features a socket cover which, upon placing a processor appropriately, is tightened to hold the processor in place. The socket type of the motherboard determines what family of processors is compatible with the motherboard, and thus socket type is a primary consideration in selecting a potential system board.

Memory Slots

Memory slots, or RAM slots, provide the interface between your motherboard and system memory modules. The amount and availability of memory slots depends largely on the form factor and intended use of the system board. For instance, many laptop motherboards have integrated memory and disallow expansion, while a server's motherboards would provide a large number of DIMM slots to provide for a much larger memory expansion.

PCI/PCI Express Slots

PCI stands for Peripheral Component Interconnect, and is provided by many motherboards (often as PCI Express) as a high speed computer expansion slot. PCI Express has become the current industry standard, though PCI remains a common expansion type on many older motherboards. As of 2012, PCI Express has been adopted as the primary motherboard-level interconnect.

Northbridge Chipset

The northbridge is one of two chips in a motherboard's chipset. The northbridge chip handles communication between the processor and (typically) the RAM, the PCIe slots, and the south bridge. In motherboards which support AGP graphic controller interfacing, the northbridge also communicates with the AGP.

Southbridge Chipset

The southbridge chip operates opposite the northbridge, completing the chipset. The southbridge is responsible for handling lower speed interfacing, like those with USB, Audio, Serial, Parallel, PCI (older) and Hard Drive connections.

I hope to have reduced the complexities of motherboard functionality to a reasonable level. I used a 87h5127 IBM motherboard for my own reference, though hopefully the pictures provided here clue you into general motherboard component placement. Thanks for reading, and look for more content in the future! 

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