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US 7,924,708 B2Granted
Method and apparatus for flow control initialization
AssigneeIntel Corporation
InventorAaron T. Spink
Life of this patent
Estimating the term…
Abstract
According to one embodiment of the invention, a credit/debit flow control mechanism performs credit initialization by a combination of standard protocol level messages (e.g., one or more flits) with encoded credit return values and the use of saturating counters.
Claims14
A method comprising:
- setting credit levels of a transmitting device of a credit and debit flow control system to zero, the credit levels adapted to control an output of messages from the transmitting device;
- initializing the system by returning credits through a series of standard protocol level messages each including a credit return value in lieu of setting the transmitting device to a predetermined maximum credit value at initialization, the credits are separated by virtual network;
- and
- extracting the credit return value from a standard protocol level message and, where the credit return value does not denote a Null message, incrementing a counter in the transmitting device by a credit level specified by the credit return value provided that the credit level does not cause the counter to exceed a maximum credit level supported by the counter.
1 more element
A device comprising:
- a saturating counter to maintain a credit level adapted to control a flow of information from the device, the saturating counter being adapted to maintain the credit level for a buffer that is either (i) shared by a plurality of virtual channels or (ii) dedicated to a virtual channel of the plurality of virtual channels;
- logic to set the saturating counter to zero and to initialize the device by adjusting the credit level of the saturating counter based on a credit return value stored within a header of a standard protocol level message provided from a second device in communication with the device, the logic to further extract the credit return value from the standard protocol level message, decode the credit return value being an encoded value, and, where the credit return value does not denote a Null message, increment the saturating counter by a credit level specified by the credit return value provided that the credit level does not cause the saturating counter to exceed a maximum credit level supported by the saturating counter.
A system comprising:
- a first processor including a counter that is adapted to maintain a credit level for controlling an output of messages from the first processor, the counter initially being set to zero;
- a second processor to initialize the system by returning credits through a series of standard protocol level messages to the first processor, each of the protocol level messages including a credit return value that represents the credit level for either (i) a virtual network or (ii) a virtual channel of a non-shared virtual network,
- wherein the first processor and the second processor are processor cores placed in a single semiconductor package to form a multi-processor component, and
- wherein the first processor to extract the credit return value from the standard protocol level message and, where the credit return value does not denote a Null message, incrementing the counter by a credit level specified by the credit return value provided that the credit level does not cause the counter to exceed a maximum credit level supported by the counter.
1 more element
Dependencies are inferred from the claim text.