Electrical computers and digital data processing systems: input/ – Input/output data processing – Input/output data buffering
Reexamination Certificate
1999-12-21
2004-03-30
Perveen, Rehana (Department: 2182)
Electrical computers and digital data processing systems: input/
Input/output data processing
Input/output data buffering
C710S033000, C709S241000, C711S137000
Reexamination Certificate
active
06715009
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of data processing and data communication. More specifically, the present invention relates to techniques to allow resources of data processing/data communication devices to cooperatively generate results for a sink process of these devices.
2. Background Information
FIG. 1
shows a system with source process
52
feeding n resources
54
, the outputs of which are collected by sink process
56
. In some applications, any of the resources
54
is capable of performing the task, and availability is the primary reason to select one resource
54
over another. For example, a computer with multiple arithmetic logic units (ALU) might give one operation to ALU #1, and give the next operation to ALU #2. Similarly, a network switch or router with multiple look-up engines (LUE) could give the first look up task to LUE #1, and the next look up task to LUE #2. In the latter example, however, it might not be possible to insure that all look-up actions terminate in the same amount of time, and therefore, the operations can finish out of order.
An example such potential out-of-order finish look-up task is look-ups performed by switches/routers to determine data associated with addresses (IP, MAC or otherwise).
FIG. 2
illustrates how such look-ups are typically performed, that is by looking for matches between a presented query number
102
and a set of threaded entries
104
. Each entry
106
consists of comparand
108
, payload
110
and pointer
112
. Each pointer
112
points to the location of the next entry, except for the last entry
106
, whose “pointer”
112
is set to null. The query number
102
is mapped to an initial pointer
114
that points to the beginning of the thread. At each entry, the comparand
108
is matched against the query number
102
. If they agree, the look up is successful, and the associated payload
110
is reported as the look up result. If they disagree, and the associated pointer
112
is non-zero, the look up process continues with the next entry
116
. The process continues until either a match is found, or the last entry
106
is encountered, where the associated pointer is null (or zero). In such case, the look up process reports failure. Accordingly, each look-up may take different amount of time, and sequentially dispatched look-ups may as a result finish out-of-order.
Thus, a mechanism that can facilitate the resources to cooperatively generate results for a sink process is desired.
SUMMARY OF THE INVENTION
An apparatus is provided with a first and a second first in, first out storage structure (FIFO) that are correspondingly associated with a first and a second resource. The apparatus is further provided with first and second control logic correspondingly coupled to the first and the second FIFO to write a first and a second control value into a first and a second current write storage location of the first and the second FIFO respectively when the first resource is assigned with a first task. The first and second control logic further write the second and the first control value into a third and a fourth current write storage location of the first and the second FIFO respectively when the second resource is assigned with a second task.
REFERENCES:
patent: 4839866 (1989-06-01), Ward et al.
patent: 5323399 (1994-06-01), Kurano
patent: 5502822 (1996-03-01), Takebe
patent: 5530458 (1996-06-01), Wakasu
patent: 5940863 (1999-08-01), Fimoff et al.
patent: 6335940 (2002-01-01), Ma
patent: 6530000 (2003-03-01), Krantz et al.
patent: 6567315 (2003-05-01), Takase et al.
Blakely , Sokoloff, Taylor & Zafman LLP
Intel Corporation
Mai Rijue
Perveen Rehana
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