L2 cache

jp198780 · 11-19-2006, 03:43 PM

what does the L2 cache do? and why is a higher L2 cache better?

StrangleHold · 11-19-2006, 04:07 PM

Its a small amout of memory on the CPU that hold data that you use over and over so it can access it faster instead of going through the harddrive and system ram!!

robina_80 · 11-19-2006, 05:58 PM

what does L1 cache do then?

fade2green514 · 11-19-2006, 05:59 PM

no, it doesnt hold the memory over and over... it "remembers" what its done and locations in the memory. generally it helps slightly with memory bandwidth and if you're doing a continuous process, like hardcore gaming or really any prolonged cpu intensive process.

L1 cache holds instruction sets, like sse3 and the like. if im not mistaken, that is.
http://en.wikipedia.org/wiki/CPU_cache
the difference between 128kb and 1mb of L2 cache is large, whereas the difference between 1mb and 4mb is quite small... as of right now though, im sure cpu's will require a much larger cache as we start using more and more memory intensive applications like Quake 4 for instance uses between 1.2 and 1.8gb of system memory when configured on ultra settings...

StrangleHold · 11-19-2006, 06:18 PM

Quote:

Originally Posted by fade2green514

no, it doesnt hold the memory over and over

Who said that

StrangleHold · 11-19-2006, 06:28 PM

When the processor wishes to read or write a location in main memory, it first checks whether that memory location is in the cache. This is accomplished by comparing the address of the memory location to all tags in the cache that might contain that address. If the processor finds that the memory location is in the cache, we say that a cache hit has occurred, otherwise we speak of a cache miss. In the case of a cache hit, the processor immediately reads or writes the data in the cache line. The proportion of accesses that result in a cache hit is known as the hit rate, and is a measure of the effectiveness of the cache

Said easier
The L1 cache is like the desk. Data here is very close at hand and well organized so that it’s quickly located. The larger the desk (L1 cache), the greater the chance that the information you need is available for fast retrieval. L2 cache is similar to the shelves behind the desk. It's closer than the main memory (file cabinets across the room), but getting information from the L2 cache still takes longer than from the L1 cache. You have quick access, but there is a slight delay when retrieving the information.

kof2000 · 11-19-2006, 10:38 PM

it only holds for a few seconds.

**Cromewell** · 11-19-2006, 11:52 PM

Quote:

it only holds for a few seconds.

It holds it until it needs that space for something else.

Quote:

The L1 cache is like the desk. Data here is very close at hand and well organized so that it’s quickly located. The larger the desk (L1 cache), the greater the chance that the information you need is available for fast retrieval. L2 cache is similar to the shelves behind the desk. It's closer than the main memory (file cabinets across the room), but getting information from the L2 cache still takes longer than from the L1 cache. You have quick access, but there is a slight delay when retrieving the information.

Nice analogy. There's more to understanding how it works than that but it's a good overview.

StrangleHold · 11-20-2006, 12:01 AM

In a even more simple explanation, its a cheap way to make your CPU-Harddrive and Ram seem faster than they really are

jp198780 · 11-20-2006, 01:18 AM

oo ok, soo i guess more is better, my current CPU in my 240 is 128KB L2, the original was 256KB..

11-19-2006, 03:43 PM	#1 (permalink)
jp198780 Diamond Member Join Date: Mar 2006 Location: Deptford, New Jersey Age: 17 Posts: 4,090	L2 cache what does the L2 cache do? and why is a higher L2 cache better? __________________ My computer:Amd x2 4200+@2.20ghz 1gb ram 200gb 7200rpm hard drive X1950XT xp home

11-19-2006, 04:07 PM	#2 (permalink)
StrangleHold Diamond Member Join Date: Nov 2005 Location: In a realm of unknown Wonders Posts: 7,084	Its a small amout of memory on the CPU that hold data that you use over and over so it can access it faster instead of going through the harddrive and system ram!! __________________ NZXT Apollo Athlon 64 X2 5600+ Gigabyte GA MA770 DS3 G Skill DDR2 800 4gb PNY XLR8 8800GT Spinpoint F1 500gb. Too bad stupidity isn't painful.

11-19-2006, 05:58 PM	#3 (permalink)
robina_80 Diamond Member Join Date: Aug 2004 Location: LONDON Age: 24 Posts: 1,913	what does L1 cache do then? __________________ Windows Vista Home Pre x32 AMD 4200X2 S939 512K (2.2) 512M ASUS EN7600GSTOP SILENT 1x80Gb 1x320gb SATA2 2Gb Dual Channel PC3200 Non-ECC DDR Memory Gbyte K8N PRO SLi s939 nF4 530W TAGAN 2FORCE T530-U22 Clabs Aud 2 ZS 7.1 OEM

11-19-2006, 05:59 PM	#4 (permalink)
fade2green514 Diamond Member Join Date: Nov 2005 Location: buffalo ny Age: 19 Posts: 3,371	no, it doesnt hold the memory over and over... it "remembers" what its done and locations in the memory. generally it helps slightly with memory bandwidth and if you're doing a continuous process, like hardcore gaming or really any prolonged cpu intensive process. L1 cache holds instruction sets, like sse3 and the like. if im not mistaken, that is. http://en.wikipedia.org/wiki/CPU_cache the difference between 128kb and 1mb of L2 cache is large, whereas the difference between 1mb and 4mb is quite small... as of right now though, im sure cpu's will require a much larger cache as we start using more and more memory intensive applications like Quake 4 for instance uses between 1.2 and 1.8gb of system memory when configured on ultra settings... __________________ Core 2 Duo e6300 (2.71ghz o/ced)(Q6600 soon!) Thermaltake Big Typhoon CPU cooler DFI Infinity 975X motherboard 7800gt 256mb + NV silencer (HD 4850 soon!) 2x2gb G.Skill ddr2-800 4-4-4-12 (2.1v) 2x80gb WD 8mb sata2 in RAID 0 system drive 1x250gb Seagate 7200.9 storage drive Windows Vista x64 Last edited by fade2green514; 11-19-2006 at 06:03 PM.

11-19-2006, 06:28 PM	#6 (permalink)
StrangleHold Diamond Member Join Date: Nov 2005 Location: In a realm of unknown Wonders Posts: 7,084	When the processor wishes to read or write a location in main memory, it first checks whether that memory location is in the cache. This is accomplished by comparing the address of the memory location to all tags in the cache that might contain that address. If the processor finds that the memory location is in the cache, we say that a cache hit has occurred, otherwise we speak of a cache miss. In the case of a cache hit, the processor immediately reads or writes the data in the cache line. The proportion of accesses that result in a cache hit is known as the hit rate, and is a measure of the effectiveness of the cache Said easier The L1 cache is like the desk. Data here is very close at hand and well organized so that it’s quickly located. The larger the desk (L1 cache), the greater the chance that the information you need is available for fast retrieval. L2 cache is similar to the shelves behind the desk. It's closer than the main memory (file cabinets across the room), but getting information from the L2 cache still takes longer than from the L1 cache. You have quick access, but there is a slight delay when retrieving the information. __________________ NZXT Apollo Athlon 64 X2 5600+ Gigabyte GA MA770 DS3 G Skill DDR2 800 4gb PNY XLR8 8800GT Spinpoint F1 500gb. Too bad stupidity isn't painful.

11-19-2006, 10:38 PM	#7 (permalink)
kof2000 Diamond Member Join Date: Aug 2004 Location: Oahu Age: 26 Posts: 6,273	it only holds for a few seconds. __________________ QX9650@4.2 swiftech \|9600@3.0 9700 nt 780i \| 790fx 8gb ddr1200 \| 8gb ddr1200 2x150gb 3x1tb \|2x250gb 3x8800gtx \|3x2900xt 1gb 2x20xdvdrw \|2x20xdvdrw 15in1 card reader \|15in1 card reader ng15/g9 \|ng15/g9 1200w psu \|1200w psu 2x28" LCD \|2x28" LCD

11-20-2006, 12:01 AM	#9 (permalink)
StrangleHold Diamond Member Join Date: Nov 2005 Location: In a realm of unknown Wonders Posts: 7,084	In a even more simple explanation, its a cheap way to make your CPU-Harddrive and Ram seem faster than they really are __________________ NZXT Apollo Athlon 64 X2 5600+ Gigabyte GA MA770 DS3 G Skill DDR2 800 4gb PNY XLR8 8800GT Spinpoint F1 500gb. Too bad stupidity isn't painful.

11-20-2006, 01:18 AM	#10 (permalink)
jp198780 Diamond Member Join Date: Mar 2006 Location: Deptford, New Jersey Age: 17 Posts: 4,090	oo ok, soo i guess more is better, my current CPU in my 240 is 128KB L2, the original was 256KB.. __________________ My computer:Amd x2 4200+@2.20ghz 1gb ram 200gb 7200rpm hard drive X1950XT xp home

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