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''Memory latency'' is the time (the latency) between initiating a request for a
/ref>
Overview of the different kinds of Memory Latency
Article and Analogy of the Effects of Memory Latency
Computer memory {{Compu-hardware-stub ar:كمون ذاكرة el:Λανθάνων χρόνος προσπέλασης μνήμης he:זמן אחזור hu:Memóriakésleltetés ru:Тайминги
''Memory latency'' is the time (the latency) between initiating a request for a byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
or word in memory until it is retrieved by a processor
Processor may refer to:
Computing Hardware
* Processor (computing)
**Central processing unit (CPU), the hardware within a computer that executes a program
*** Microprocessor, a central processing unit contained on a single integrated circuit (I ...
. If the data are not in the processor's cache, it takes longer to obtain them, as the processor will have to communicate with the external memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
cells. Latency is therefore a fundamental measure of the speed of memory: the less the latency, the faster the reading operation.
Latency should not be confused with memory bandwidth
Memory bandwidth is the rate at which data can be read from or stored into a semiconductor memory by a central processing unit, processor. Memory bandwidth is usually expressed in units of bytes per second, bytes/second, though this can vary for ...
, which measures the throughput
Network throughput (or just throughput, when in context) refers to the rate of message delivery over a communication channel, such as Ethernet or packet radio, in a communication network. The data that these messages contain may be delivered ov ...
of memory. Latency can be expressed in clock cycles or in time measured in nanoseconds. Over time, memory latencies expressed in clock cycles have been fairly stable, but they have improved in time.Crucial Technology, "Speed ''vs.'' Latency: Why CAS latency isn't an accurate measure of memory performance/ref>
See also
*Burst mode (computing) Burst mode is a generic electronics term referring to any situation in which a device is transmitting data repeatedly without going through all the steps required to transmit each piece of data in a separate transaction. Advantages
The main advantag ...
* CAS latency
Column Address Strobe (CAS) latency, or CL, is the delay in clock cycles between the READ command and the moment data is available. In asynchronous DRAM, the interval is specified in nanoseconds (absolute time). In synchronous DRAM, the interval ...
* Multi-channel memory architecture
In the fields of digital electronics and computer hardware, multi-channel memory architecture is a technology that increases the data transfer rate between the DRAM memory and the memory controller by adding more channels of communication betwee ...
* Interleaved memory
In computing, interleaved memory is a design which compensates for the relatively slow speed of dynamic random-access memory (DRAM) or core memory, by spreading memory addresses evenly across memory banks. That way, contiguous memory reads and w ...
* SDRAM burst ordering
Synchronous dynamic random-access memory (synchronous dynamic RAM or SDRAM) is any DRAM where the operation of its external pin interface is coordinated by an externally supplied clock signal.
DRAM integrated circuits (ICs) produced from the ea ...
* SDRAM latency
Memory timings or RAM timings describe the timing information of a memory module. Due to the inherent qualities of VLSI and microelectronics, memory chips require time to fully execute commands. Executing commands too quickly will result in data ...
References
External links
Overview of the different kinds of Memory Latency
Article and Analogy of the Effects of Memory Latency
Computer memory {{Compu-hardware-stub ar:كمون ذاكرة el:Λανθάνων χρόνος προσπέλασης μνήμης he:זמן אחזור hu:Memóriakésleltetés ru:Тайминги