 | This article includes alist of references,related reading, orexternal links,but its sources remain unclear because it lacksinline citations. Please helpimprove this article byintroducing more precise citations.(March 2022) (Learn how and when to remove this message) |
In computer technology,transfers per second and its more common secondary termsgigatransfers per second (abbreviated asGT/s) andmegatransfers per second (MT/s) are informal language that refer to the number of operations transferring data that occur in each second in some givendata-transfer channel. It is also known assample rate, i.e. the number of data samples captured per second, each sample normally occurring at the clock edge. The terms are neutral with respect to the method of physically accomplishing each such data-transfer operation; nevertheless, they are most commonly used in the context oftransmission of digital data. 1 MT/s is 106 or one million transfers per second; similarly, 1 GT/s means 109, or equivalently in the US/short scale, onebillion transfers per second.
These terms alone do not specify thebit rate at which binary data is being transferred because they do not specify the number of bits transferred in each transfer operation (known as the channel width orword length). In order to calculate the data transmission rate, one must multiply the transfer rate by the information channel width. For example, a data bus eight-bytes wide (64 bits) by definition transfers eight bytes in each transfer operation; at a transfer rate of 1 GT/s, the data rate would be 8 × 109 B/s, i.e. 8 GB/s, or approximately 7.45 GiB/s. Thebit rate for this example is 64 Gbit/s (8 × 8 × 109 bit/s).
The formula for a data transfer rate is:Channel width (bits/transfer) × transfers/second = bits/second.
Expanding the width of a channel, for example that between a CPU and anorthbridge, increases datathroughput without requiring an increase in the channel's operating frequency (measured in transfers per second). This is analogous to increasing throughput by increasing bandwidth but leavinglatency unchanged.
The units usually refer to the "effective" number of transfers, or transfers perceived from "outside" of a system or component, as opposed to the internal speed or rate of the clock of the system. One example is acomputer bus running atdouble data rate where data is transferred on both the rising and falling edge of the clock signal. If its internal clock runs at 100 MHz, then the effective rate is 200 MT/s, because there are 100 million rising edges per second and 100 million falling edges per second of a clock signal running at 100 MHz.
Buses likeSCSI andPCI fall in the megatransfer range of data transfer rate, while newer bus architectures like thePCI-X,PCI Express,Ultra Path, andHyperTransport /Infinity Fabric operate at the gigatransfer rate.
The choice of the symbolT fortransfer conflicts with theInternational System of Units, in which T is the symbol for thetesla, a unit ofmagnetic flux density (so "megatesla per second" (MT/s) would be a reasonable unit to describe the rate of a rapidly changing magnetic field, such as in apulsed field magnet orkicker magnet).