llquantize() Function

The llquantize() action stores unsigned 64-bit values in buckets similar to the lquantize() action. Because llquantize() presents a log-linear quantization, the arguments to llquantize() are different from those for lquantize(). The arguments to the llquantize() action are:

• Value of interest

• A factor – The base of the logarithm

• Lower magnitude of the log-linear quantization, which is the first set of buckets that cover the values n * factor ^ lower magnitude

• Upper magnitude of the log-linear quantization, which is the last set of buckets that cover the values n * factor ^ upper magnitude

• Step value – Each magnitude contains this number of buckets

The first 64-bit word in the data encodes the factor, low magnitude, high magnitude, and steps. Each is encoded as an unsigned 16-bit integer. You can extract these values of encoded data by using the following macros:

• DTRACE_LLQUANTIZE_FACTOR(x)

• DTRACE_LLQUANTIZE_LMAG(x)

• DTRACE_LLQUANTIZE_HMAG(x)

• DTRACE_LLQUANTIZE_STEPS(x)

The remaining values in the data are:

• The underflow bucket

• Sets of buckets for each magnitude

• Overflow data

The factor and the value of the steps determines the number of buckets at each level. If the magnitude is zero, there are only factor-1 buckets. If the magnitude is other zero, there are steps - steps/factor buckets per magnitude.

For example, if factor == 10 and steps == 20, there are 20 - 20/10 == 18 buckets per magnitude. However, if the magnitude is 0, there are 10 - 1 == 9 buckets: 1x10^0 through 9x10^0.

llquantize() (dtrd_action == DTRACEAGG_LLQUANTIZE)

Data Format for the llquantize() Action