DRAM acts as a cache for the disk. Although DRAM is faster than the disk, it's still pokey. So data that's needed more often is moved up to the next faster memory, called the Level 2 L2 cache.
Computerworld QuickStudies At the highest level, the most frequently used information - say, the instructions in a loop which execute repeatedly - is stored directly on a special section of the processor chip, called Level 1 L1 cache.
This is the fastest memory of all. Intel Corp. The L2 cache on the CPU chip can be accessed four times faster than if it were on a separate chip. When the processor needs to execute an instruction, it looks first in its own data registers. If the needed data isn't there, it goes to the L1 cache and then to the L2 cache.
It might not even be there, in which case the system has to retrieve it from the disk. When the CPU finds data in one of its cache locations, it's called a "hit"; failure to find it is a "miss. For high-end processors, it can take from one to three clock cycles to fetch information from L1, while the CPU waits and does nothing. It takes six to 12 cycles to get data from an L2 on the processor chip, and dozens or even hundreds of cycles for off-CPU L2.
Caches are more important in servers than in desktop PCs because servers have so much traffic between processor and memory generated by client transactions. Although the bus connecting processor and memory ran only at 25 MHz, this cache let many programs run entirely within the chip at 50 MHz.
Virtual memory allows a computer to run multiple programs separately without risking loss of data. The operating system not only moves data to storage, it also links active memory to the inactive memory on those disks to keep everything operating efficiently.
You, the end user, are never aware any of this is taking place. If you find your computer is sluggish, there are some things you can do without having to buy a new computer or dig too far into the inner workings of the one you have. When you shut your computer down, the processor cache and RAM deplete completely. Restarting your computer can instantly repair any issues that are related to memory.
It could simply be a matter of a certain application running in the background, consuming far too much memory. Either deleting or setting that application not to open at startup can fix that problem in just a few steps. The more RAM your system has, the more programs you can run at once without affecting performance. This is especially true if you participate in memory-intensive activities like video streaming and gaming.
Your CPU will also factor heavily into how well your computer performs. An Intel or AMD processor is the best way to go. If you merely want to pick up performance, more RAM is one of the easiest ways to give your computer a pick-me-up. Older PCs often will only go as far as DDR3, so you may need to invest in older modules if you want to stay with your current motherboard. Stephanie Faris is a novelist and business writer whose work has appeared on numerous small business blogs, including Zappos, GoDaddy, 99Designs, and the Intuit Small Business Blog.
She worked for the State of Tennessee for 19 years, the latter six of which were spent as a supervisor. She has written about business for entrepreneurs and marketing firms since How Important Is a Processor Cache? By Stephanie Faris Updated April 23, Core i7 Vs. Quad Core What Is i5 Technology? L1 cache — This is the primary cache. It is typically embedded in the processor chip. Yet, even a small kB or kB cache is enough to deliver substantial performance gains that most of us take for granted today.
There are various ways of implementing cache hierarchies. Most PC systems have processors with a small first-level cache L1, up to kB , which is often divided into a data cache and an instruction cache. L2 caches can work exclusively or inclusively, which means that they either store a copy of the L1 contents - or they don't.
AMD will soon offer a third cache level, which will be used as a shared cache memory for the AMD Phenom processors with up to four cores. The same is anticipated for Intel's Nehalem processor architecture, which will replace Core 2. L1 cache has always been on the processor, while first L2 caches were implemented onto motherboards, as it was the case with many DX computers and Pentium machines. Simple SRAM chips static RAM were used as first-cache memory; pipelined burst cache took over soon Pentium until on-chip and on-die caches became possible.
The Pentium Pro at to MHz was the first processor to host kB L2 cache memory inside the CPU, making it the largest ceramic package ever on desktops or workstations.
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