Name
Abstract | ||
|---|---|---|
The ultimate goal of the SCI standard is to support memory coupling of different SCI nodes, where remote memory accesses are
handled entirely by the hardware. So one may ask: Why do we need a driver? At least using the memory of a ‘usual’ computer
needs no driver, so where is the difference? The answer is simple: There is no difference in using the memory, SCI memory looks just slower for the processor whenever the SCI hardware has to fetch a remote cache line.
The task of an operating system is to provide a virtual view to all processes: they all see their own virtual version of the
machine, more or less perfectly isolated from other processes. The current situation is to do some of this virtualization
in hardware (e.g. address translation and protection by the MMU), and some in software (e.g. time-slicing, file handling).
Which parts are done in hardware mostly depends on efficiency considerations. Emulating a MMU in software is possible, but
rather slow.
The MMU does only one part of the memory handling, translation of virtual to physical addresses and signaling faults to the
operating system. The other part of management is still done by the operating system. The memory management is usually tightly
coupled with file system caches, a way to avoid expensive copy operations of large memory blocks.
What is changed by putting SCI hardware into a node? On the hardware level, there are two changes: a node can access local
physical memory and parts of the 64-bit SCI memory space visible in its physical address space. Access to all memory areas
is still handled by hardware, but there is the need to manage how remote memory is accessed. Today’s operating systems are
not prepared to handle this, making drivers necessary which handle proper allocation of local and remote memory resources.
This puts many management tasks into the driver, making it complicated compared to other drivers that access only a ‘simple’
device.
|
Year | DOI | Venue |
|---|---|---|
1999 | 10.1007/10704208_13 | Scalable Coherent Interface |
Keywords | Field | DocType |
interfacing sci device drivers,memory management,operating system | Address space,Extended memory,Flash file system,CPU cache,Computer science,Device file,Remote direct memory access,Conventional memory,Operating system,Memory management (operating systems) | Conference |
ISBN | Citations | PageRank |
3-540-66696-6 | 0 | 0.34 |
References | Authors | |
5 | 2 | |
Name | Order | Citations | PageRank |
|---|---|---|---|
| Roger Butenuth | 1 | 8 | 2.96 |
| Hans-ulrich Heiss | 2 | 209 | 29.25 |