Dynamic selection of a compression algorithm for trace data

1. A tracing system, comprising:

a trace bus; and

compression selection circuitry, said compression selection circuitry configured to receive a trace data input from a source of trace data and determine a compression method for a piece of trace data selected for transmission on said trace bus, said compression selection circuitry selecting the compression method from a set of compression methods based on at least one compression criterion;

said tracing system signaling the compression method that was used to compress a piece of compressed trace data selected for transmission;

wherein said tracing system signals the trace data type of said selected piece of compressed trace data.

2. The tracing system of claim 1 , wherein said compression selection circuitry implements a set of different compression methods in parallel on said piece of trace data to generate a corresponding set of pieces of compressed trace data compressed by different compression methods, said compression selection circuitry selecting a piece of compressed trace data for transmission based on comparing compression results of said set of pieces of compressed trace data compressed by different compression methods.

3. The tracing system of claim 2 , wherein said tracing system selects the piece of compressed trace data compressed by the compression method that has the best compression efficiency.

4. The tracing system of claim 2 , wherein said tracing system selects the piece of compressed trace data compressed by the compression method based on compression quality.

5. The tracing system of claim 2 , wherein said tracing system selects the piece of compressed trace data compressed by the compression method based on a level of trace data compression.

6. The tracing system of claim 1 , wherein said source of trace data has a plurality of different trace data types.

7. The tracing system of claim 1 , wherein said compression selection circuitry comprises:

a plurality of compression modules that each receive input trace data from a source of trace data having a plurality of different trace data types, each of said plurality of compression modules implementing a different compression method to compress a piece of trace data such that said plurality of compression modules produces a corresponding plurality of pieces of compressed trace data for each piece of input trace data; and

a compression selector module coupled to said plurality of compression modules to compare compression results of said plurality of pieces of compressed trace data and select the piece of compressed trace data that exhibits a desired level of trace data compression for transmission on said trace bus.

8. The tracing system of claim 1 , further comprising a First In First Out (FIFO) buffer that is coupled to said compression selection circuitry, said FIFO buffer storing said selected piece of compressed trace data prior to transmission on said trace bus.

9. The tracing system of claim 1 , wherein said set of different compression methods includes one or more of delta compression, hit-block compression, run-length encoding, and variable bit-block compression.

10. A computer readable storage medium, comprising:

computer-readable program code stored on said computer readable medium implemented as a semiconductor memory, magnetic disk or optical disk, said computer-readable program code causing a computer to describe compression selection circuitry for a tracing system, said compression selection configured to receive a trace data input from a trace bus and determine a compression method for a piece of trace data selected for transmission on said trace bus, said compression selection circuitry selecting the compression method from a set of compression methods based on at least one compression criterion; wherein said tracing system signals the trace data type of said selected piece of compressed trace data.

11. A tracing method, comprising:

compressing a piece of trace data having one of a plurality of different trace data types using a plurality of compression circuitry modules to produce a corresponding plurality of pieces of compressed trace data;

selecting one of said plurality of pieces of compressed trace data based on at least one compression criterion;

outputting said selected piece of compressed trace data on a trace bus; and

signaling the compression method used to produce said selected piece of compressed trace data; comprising signaling the trace data type of said selected piece of compressed trace data.

12. The tracing method of claim 11 , wherein said selecting comprises comparing compression results of said plurality of pieces of compressed trace data and making a selection based on compression efficiency.

13. The tracing method of claim 11 , wherein said selecting comprises determining which of said plurality of pieces of compressed trace data exhibits a desired level of trace data compression and choosing one of said plurality of pieces of compressed trace data based upon said determination.

14. The tracing method of claim 11 , wherein said compressing includes compressing said piece of trace data with one or more of delta compression, bit-block compression, run length encoding, and variable bit-block compression.

15. The tracing method of claim 11 , wherein said selecting is based on a default selection.

16. The tracing system of claim 11 , wherein said set of different compression methods includes one or more of delta compression, bit-block compression, run-length encoding, and variable bit-block compression.