Multicore: In this two or more processors
are combined to get improved performance, efficient
parallel processing and reducing power consumption.
A dual core processor setup has multiple separate processors
installed in same computer, these two processors are
plugged in same socket so connection between them is
A multi-threaded processor executes
the instructions in parallel, but shares the other resources
like registers. A multi-processor system, on the other
hand have independent support units. Therefore, other
things being equal, a multi processor system is more
efficient than a multi-threaded processor based computer.
Further, a multi-threaded processor is a single chip
where as a multi-processor system will have several
independent processor chips
There are 3 levels of cache
L1 cache : It is closer to processor and it runs
at processors speed not at motherboard speed. It
ranges from 8KB to 64KB and uses SRAM.
L2 cache: It is separate from processor and uses
back side bus. Also, called as secondary cache is
used to reduce data access time in case same data
was already accessed before. Also used for buffer
program instructions and data requests by processors.
L3 cache: Not found now a days as its function
is replaced by L2 cache.
Stepping: These are minor revisions
issued by processor manufacturers for their devices
over device life cycle. These are identified by special
numbers printed in body of the device.
VRM: Short for voltage regulator
module, a small module that installs on a motherboard
to regulate the voltage fed to the microprocessor. Nearly
all motherboards have either a built-in voltage regulator
or a VRM, the only difference being that the VRM is
replaceable. The VRM sense the required power needed
by a processor by examining the Voltage ID signal (VID)
sent during power on self test.
NX (No-Execute): It is the 63rd
bit of page table entry, it allows OS to specify which
pages if virtaul address space can can contain executable
code and which cannot. If any page marked as No-execute
is used for execute code will cause memory error.
XD(Execute Disable): It provides
same functionality as NX for recent x86 Intel processors.
Hyperthreating: It is term used
by Intel® for simultaneous threading
here a single processor appear as two virtual processors
to th operating system.
Intel and AMD integrate virtualization support into
VT(Intel® Virtualization Technology)
VT-x which provide basic support for vitualization
VT-d ( Virtualization technology for Directed
I/O ) provide support for virtualization of I/O
VT-c (Virtualization technology for Connectivity
AMD-V( Advanced Micro Devices Virtualization
technology ): Its functionality is similar
to VT-x. AMD-V 2.0 includes extra features, such as
I/O level Virtualization, and Extended Migration. AMD
V 2.0 is supported only in the latest generation of
AMD server-class CPUs.
RISC is acronym for Reduced Instruction
Set Computing, information processing using microprocessor(s)
that are designed to execute computing tasks with the
simplest instructions in the shortest amount of time
possible. RISC is the opposite of CISC Servers using
RISC processors are usually designed for high end applications
with high availability and larger processing power.
Hence, RISC based servers are usually much more expensive
than Intel processor based servers.
CISC (Complex Instruction Set Computing)
chips have a large, complex instruction set. Therefore,
they typically process complex codes more quickly.