US 7,127,643 B2Granted

Method and apparatus for fixing bit errors encountered during cache references without blocking

AssigneeSun Microsystems, Inc.

InventorsMarc Tremblay, Shailender Chaudhry

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Abstract

One embodiment of the present invention provides a system that fixes bit errors encountered during references to a cache memory. During execution of an application, the system performs a reference to the cache memory by retrieving a data item and an associated error-correcting code from the cache memory. Next, the system computes an error-correcting code from the retrieved data item and compares the computed error-correcting code with the associated error-correcting code. If the computed error-correcting code does not match the associated error-correcting code a bit error has occurred. In this case, the system stores an identifier for the reference in a register within a set of one or more registers associated with the cache memory, so that the bit error can be fixed at a later time. The system also allows the application to continue executing.

Claims17

Dependent claims

A method for fixing bit errors encountered during references to a cache memory, comprising:

performing a reference to the cache memory during execution of an application;
wherein performing the reference involves retrieving a data item and an associated error-correcting code from the cache memory;
computing an error-correcting code from the retrieved data item;
and
comparing the computed error-correcting code with the associated error-correcting code;
wherein if the computed error-correcting code does not match the associated error-correcting code indicating that a bit error has occurred, the method further comprises,
storing an identifier for the reference in a set of one or more registers associated with the cache memory, so that the bit error can be fixed at a later time, and
continuing execution of the application;
and
fixing the bit error in the cache memory at the later time by:
reading the identifier for the reference from the register,
using the identifier to retrieve the data item and the associated error-correcting code,
using the associated error-correcting code to produced a corrected data item and error-correcting code, and
storing the corrected data item and error-correcting code to the cache memory;
wherein fixing the bit error involves fixing the bit error at a periodic interval determined by an operating system tick timer.

12 more elements

An apparatus that fixes bit errors encountered during references to a cache memory, comprising:

the cache memory;
an input of the cache memory that is configured to receive a reference from an application;
a retrieval mechanism that is configured to retrieve a data item and an associated error-correcting code for the reference from the cache memory;
an error-correcting code circuit that is configured to compute an error-correcting code from the retrieved data item;
a comparator that is configured to detect a bit error by comparing the computed error-correcting code with the associated error-correcting code;
a set of one or more registers for storing identifiers for errors that are detected during cache references;
an error logging mechanism, wherein if a bit error has occurred, the error logging mechanism is configured to store an identifier for the reference in a register in the set of one or more registers, so that the bit error can be fixed at a later time;
and
a bit error fixing mechanism that is configured to:
read the identifier for the reference from the register,
use the identifier to retrieve the data item and the associated error-correcting code,
use the associated error-correcting code to produced a corrected data item and error-correcting code, and to
store the corrected data item and error-correcting code to the cache memory:
wherein the bit error fixing mechanism is configured to fix bit errors at a periodic interval determined by an operating system tick timer.

11 more elements

Dependencies are inferred from the claim text.