It's a capability substantially enhance Large I/O request performance, if they are supported by the hardware. Scatter reading is the ability to deliver data blocks stored at consecutive hardware address to non-consecutive memory addresses. Gather writing is the ability to deliver blocks of date stored at non-consecutive memory addresses to consecutively addressed hardware blocks. This concept is primarily used in the Hard Disks . -----Original Message----- From: kernelnewbies-bounce@xxxxxxxxxxxx [mailto:kernelnewbies-bounce@xxxxxxxxxxxx]On Behalf Of Thekkedath Gopakumar-agt026 Sent: Friday, January 21, 2005 9:19 AM To: sanjayk; kernelnewbies@xxxxxxxxxxxx Subject: RE: Scatter-gather NIC > What exactly is meant by scatter-gather? > Does it means reading or writing data from mulitple locations > simultaneously by the NIC. One of the constraints in DMA is that the physical memory buffer sould be contiguous. A device with scatter gather capability allows the programmer to allocate many buffers (each of which is contiguous of course) at various memory locations for DMA. For example, in a network card, the driver writer can have many software buffers intented to hold say packets received by the device. The device knows the starting address of each of these buffers (how to feed this addresses to the device is device dependent) and on receiving a packet will DMA it to the next available buffer. -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
