วันพฤหัสบดีที่ 5 มีนาคม พ.ศ. 2552

Cache is important why.

• Cache What? And the Cache.



They Cache that if formally it is a type of memory. This will speed access. And high data transfer will be put on the data collected is used frequently for the CPU time to use that information. Will find it faster. The unnecessary. To go search for information from all.



Commensurate simple. Like reading books. Then when the message เจอ interesting. It noted that its book. When time information that can find the book easier to write. Open the book and find a book to write certain information in the book. Size less than. แน่ in other books. No one will continue to replicate data every Major Tad all pages of the book. Write a book on authenticity.



They came to us about our Cache per better. From the above then we will see in current use are 2 Cache is a Memory Cache and Disk Cache The principle of the 2 types of work like this is the same ie Disk Cache will be read to. want to use to keep the CPU Unit when the etch is run. Is to find the unit before the etch. If not found, it will go in search Harddisk next in the case of Memory Cache and it is an order that one next to the Disk Cache is to extract information that will be run frequently. Stored into memory in small high sensitivity than when the CPU unit and want to carve. Will want to look for information. Small memory before it. Before the unit to find that the etch. Have access to and transmission of data over the slow and small memory size, we called it that it is Cache.



For in this article. We will discuss with a single Memory Cache. So I will ask just a brief that called for it to be understood Cache match นะครับ. It means that the Memory Cache.

Cache is the location of it. Is located between the CPU unit to carve. It will retrieve the stored information or the frequently use. By the etch. Reading in a movie, or send data from Cache to CPU or from the CPU to Cache is done faster. By the CPU or to carve from the CPU unit to carve because a large SRAM which is also highly sensitive. And more expensive memory system DRAM is a very expensive price and because of this scale used in the Cache size is less than the etch unit is very similar.



DRAM or Dynamic RAM storage that will store the charge (Capacitor) which is required for the storage Refresh to Refresh this remains the cause of delay in access to information from and because it must. Refresh yourself in this own time. Cause it is called Dynamic RAM.



The SRAM is different from that match DRAM DRAM Refresh data will always be, but while the SRAM storage and that it will not automatically Refresh Refresh which will be ordered only when it is Refresh. The advantage of it. Speed is usually much faster than DRAM, but with a much higher price. It is the poorer for it as well.



From the above. Seem Cache is critical to the speed of the system is not less. Why then are we to just focus on it ? Cache is used just because the CPU or the new version?



No, actually we are using the Cache and then from the long version of the Intel 80486 which time it has started to enter the Cache CPU to enter their starting size of 8KB edition and a 486DX-33 is added to the 16KB version. 486DX4 which has been put to the Cache has entered into the core of the CPU เลย make contact between the CPU Cache is done very quickly and has been used by another Cache enter the Mainboard, which is larger than the size. behind Cache included core CPU.



For more information on any CPU. Will search from within Cache CPU core before if you want to find information (called Cache Hit) that will extract information. เลย to work but if not found (called a Cache Miss) will conduct a search in the Cache on the Mainboard and had not yet found another. Unit will go in search of the next etch step. If the unit is to carve. No data is still needed. Will continue to search in the Harddisk.



With locations in the Cache to store and different in order to run different so called Cache in the core of that CPU Internal Cache or Level 1 Cache (L1 Cache) and called on the Cache Mainboard that is External. or Cache Level 2 Cache (L2 Cache).



In Intel's Pentium CPU models that have to break out within the Cache section 2 to distinguish the work. That this issue has split from 16KB to 8KB a collection of instructions called 8KB Instruction Cache, and to collect information called Data Cache.



CPU and later versions of Intel's Pentium II that has changed the storage location of Cache Level 2, which typically is stored on the Mainboard to keep on the move Package with CPU (CPU Intel Pentium II, it will be. Cartridge style sheet is a general CPU is in the middle next to Cache and then collect a Package called "same or SECC Single Edge Contact Cartridge but still called on the Cache External Cache SECC as old or Level 2 Cache. It remains just outside the CPU on the same Package.



But with the high price of CPU Pentium II era in which it launched recently. Make a purchase with the power to use the Intel has cut the minimum level 2 Cache from Pentium II to reduce the cost of production and changing patterns Package and then call down to see some new CPU Celeron and it's called Package. that Celeron Single Edge Processor Package.



Then from the above that the Cache is priced so high when crop prices make the Cache Level 2 cheaper than the Celeron and Pentium II are much hope it will use the Intel Celeron is a low price. Market and lower middle class.



But then dreams crumble because the Celeron Cache is not in the game. Cache not run much or score equivalent to a Pentium II at the same speed but in the Office Application such as Microsoft Word, Microsoft Excell bad to do any more. Is seen from a Celeron at 300 MHz when used with the Application to be later than a Pentium MMX 233 version makes the Celeron is not a popular size.



The Intel Celeron has produced a new generation has added to the Cache Level 2 with a size 1 / 4 of the Pentium II, but to work with. Speed equals the speed of the CPU (Cache level 2 of the Pentium II running at only half the speed of the CPU) and just add to the Cache Level 2 own score by working with the Application is to come up. very different from the old version that does not significantly Cache.



This is one point per นะ Cache that is more interested, but not all the times. One other point that the Cache is mentioned. Growing at this time. Caused by the announcement of the AMD K6-III.

AMD K6-III What better to make the Cache is an interesting design. This must continue to refer back a few while ago that AMD's CPU is using Internal Cache External Cache, and the same CPU as the Intel architecture when Intel changed to a new take on the Package Cache of CPU and no. Using Cache Mainboard on longer, but the AMD is still on. Architecture was the internal CPU Internal Cache and External Cache Mainboard heads on editions from the AMD K6-2.



Sire AMD K6-III (or AMD K6-3 is but a name change. To comply with Intel Pentium III) to the AMD has increased the Cache to CPU Package of some (but not included in the core of the CPU) and still have the same Mainboard on Cache, so the use of Cache. to 3 levels with (called Tri-Level Cache) The first level is within the Cache of the CPU core is the next level Package on the CPU and the last on the Mainboard of the Cache size is large. up respectively. While the speed of deployment to reduction, respectively.



And just making the Cache is extremely interesting. All that matters is the size of the Cache, but the Celeron is running at speeds less. The CPU speed is equal to a Pentium II Celeron Cache but working with more than a half of CPU speed which กัน important than size or speed? And the Tri-Level Cache on AMD K6-III will make the system faster real? Cache has several better ไหม?



We will be out next. The details and importance of each Cache กัน next level.

• Cache Level 1 (Level 1 cache).



Cache Level 1 would be the most important. And it's location close to the CPU can cause the CPU to access very quickly. Typically, the size of it. Would like for less CPU Intel Pentium II or Intel Celeron L1 Cache size is 32 KB and only on AMD K6-2 is 64 KB in size, though that size is small but very important.




• Cache Level 2 (Level 2 cache).



The latter in search of the CPU when the search was not found in the Cache Level 1 Cache Level 2 is the size of Level 2 Cache, which will differ according to version and type of CPU that it is of course different speeds. different strategy.



From the beginning and then when other of the Celeron with a Pentium II Celeron that is only 128 KB Cache Level 2, but work with speed as the CPU is the Pentium II Cache 512 KB Level 2 to work but with the speed. only. Half the speed of the CPU which then important than speed or size.



We will see the performance comparison between the Pentium II and Celeron, which view will be the most fair because they use different cores of the same CPU as the only difference between the size and speed of Cache Level 2 only.

However, the size of Level 2 cache, it is also a key point to reduce the Performance of access disk by reading the information stored in the RAM and the key used to store frequently if the Cache Cache is a major scale. That must be read from the Cache RAM, the more slowly it can be better with the Network-File-Server Cache is a great and very soon will be better so there is a Intel Pentium II Xeon L2 Cache 512K or more. and run at speeds as the CPU.



For AMD K6, K6-2 cache, which is used on the Mainboard FSB speed matter most to K6-2 300 MHz such as the Level 2 Cache is available at 100 MHz (FSB 100 MHz), but Intel Pentium II - 300 MHz. will have a Level 2 Cache at 150 MHz and Celeron 300A is available at Level 2 Cache and 300 MHz for the AMD K6-2 is available with Pentium II does not differ much, but if a Pentium II 400 be Levl 2. Cache running at 200 MHz, while AMD K6-2 400 MHz is also working with the Cache and 100 MHz that is the same one that makes the key point in the Performance Memory Performance of AMD and Intel Pentium II inferiority. Celeron.



But for the AMD K6-3 AMD includes the Level 2 cache with the same CPU Package เลย collected by embedded CPU on the same size but with a Celeron 2 times and run at speeds as the CPU, which is. allows AMD K6-3 is more than the L2 cache and Celeron 2 as Level 2 cache is 2 times the speed of Pentium II (the same speed).

• Cache Level 3 (Level 3 cache).

AMD K6-III is a very interesting point that other one is a K6-III will have a Level 2 cache embedded in the chip CPU, but in the meantime with Mainboard for AMD K6-III is the Cache. by making it look on the Mainboard such as Cache Cache Level 3 (Level 3 Cache).

Now we try to see that if a Cache Level 3 Performance numbers will increase or decrease the size of the Cache class and how it must be 3 by much of this experimental form of Tom's Hardware compares the results of the Cache. 3 class sizes by testing with the CPU AMD K6-III (because the current model is one that is used to Cache Level 3).
When the CPU needs information to process. Will look for such information from the first level 1 Cache find that if found it will take just over 1 unit, but if not found will look to the Cache Level 2 to see if it will find use. less than 11 time units (1 +10), but if not found for. Is the time more than 11 units to find the time to carve the unit or to the Cache Level 3.



Cache Level 3 if no finding that information from the search in the Cache Level 1 and Level 2 will not find a unit to find the etch to see if that would take more than 11 (1 +10) but not time units. over 1,011 (1 +10 +1000) units at level 3 but if the Cache will go to find the Cache level 3 in which the time spent. It depends on the size of the Cache Level 3 is that if found in the Cache for a 3 that will take more than 11 time units but less than 111 (1 +10 +100) units at level 3 for Cache size and less than 512KB. 211 (1 +10 +100) for 3-level Cache Size 1024 KB and less than 411 (1 +10 +400) for 3-level Cache size 2048KB which note that. If information can be found in the Cache Level 3 is the time to use it at no less than the Cache class is more than 2-fold.



If not found ล่ะ? If you do not find the information they need in Cache level 3 will be the time to search more. Prior to the search unit to the etch. Which meets this point own. Performance is the cause that has reduced however with the large Cache Level 3 the opportunity to make you want to search. It more.



Ratio for the Level 3 to Level 2 is the key. The same. Ratio between the CPU Level 1/Level 2 if you want to look for information on any level Cache will not search in the Cache next level which is later than speed. But is larger than. However, if the Cache class size is not the next big opportunity to find the information they need เจอ is less (because they have less space to make the opportunity to retrieve data from RAM and then to match it. Is less than) that makes CPU time to waste search (if search was not found), then it will slow over the Performance of the ratio should normally be between Cache and then the next level. Prior to the Cache class is 4:1 such as Level 2 Cache / Level 1 Cache of the Celeron is 128:32 (4:1) and K6-3 is 256:64 (4:1) except that the Pentium II. is 512:32 (16:1).



AMD has asserted that the Cache 1Mb on Mainboard Performance will increase 3-4% (L3/L2 = 1024/256 = 4 / 1), which currently is the Cache 1M Mainboard with 512 K and hence to choose. This is a continuing help in determining a นะครับ then. For those who think using the AMD K6-3 Mainboard What use will that be good for disable Level 3 Cache think that is possible through BIOS, it will be effective in helping to Overclock more.



We now go back and try to see at first. I compare the writing on Cache Notebook shortened version of the book. We could have concluded that. Brain of a Cache Level 1 because we read and see that message when ไหน. Which sentence or the most memorable. Students may train students would probably already here that teachers must take the test out of แน่. Repetition will read it over and when the ability to repetition. Notebook to write it into the stands a small book that is Cache Level 2 in there and maybe read. May also have other very interesting stories. Notebook can not write the summary. It may draw text using a pen or key barrier to the page that is there ครับ Cache level 3.



then it considered that the size of Cache is important to the speed of Cache is too important, but if to choose between a Celeron 300A, the Level 2 cache 128 K works at speeds as the CPU with a Pentium II 300. L2 cache 512 K as a half. But the price is different when the same as in Performance in the Business is not about virtually no difference between the Celeron is better option (much cheaper set).



But had to use the Business by it would then need to select a CPU Cache before much of it though because Cache is faster but less size. The percentage of data found in the Cache find it even less will be offset by the speed. Cache but it makes the burden must be more to.

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