Hardware Reference
In-Depth Information
To see additional processors with SYSmark scores of 100 or higher and processors with
scores under 100, see www.anandtech.com/bench/CPU/2 .
TheSYSmarkbenchmarksarecommerciallyavailableapplication-basedbenchmarksthat
reflectthenormalusageofbusinessusersemployingmodernInternetcontentcreationand
office applications. However, it is important to note that the scores listed here are pro-
duced by complete systems and are affected by things such as the specific version of the
processor, the motherboard and chipset used, the amount and type of memory installed,
the speed of the hard disk, and other factors. For complete disclosure of the other factors
resulting in the given scores, see the reports on the BAPCo website at www.bapco.com .
Cache Memory
As processor core speeds increased, memory speeds could not keep up. How could you
runaprocessorfasterthanthememoryfromwhichyoufeditwithouthavingperformance
sufferterribly?Theanswerwascache.Initssimplestterms, cache memory isahigh-speed
memory buffer that temporarily stores data the processor needs, allowing the processor
to retrieve that data faster than if it came from main memory. But there is one additional
feature of a cache over a simple buffer, and that is intelligence. A cache is a buffer with a
brain.
Abufferholdsrandomdata,usuallyonafirst-in,first-outbasisorafirst-in,last-outbasis.
A cache, on the other hand, holds the data the processor is most likely to need in advance
of it actually being needed. This enables the processor to continue working at either full
speed or close to it without having to wait for the data to be retrieved from slower main
memory. Cache memory is usually made up of static RAM (SRAM) memory integrated
into the processor die, although older systems with cache also used chips installed on the
motherboard.
See Cache Memory: SRAM , p. 319 ( Chapter 6 ) .
Forthemajorityofdesktopsystems,therearetwolevelsofprocessor/memorycacheused
in a modern PC: Level 1 (L1) and Level 2 (L2). An increasing number of high-perform-
anceprocessorsalsohaveLevel3cache.Thesecachesandtheirfunctioningaredescribed
in the following sections.
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