HDF_title.gif (21122 bytes)Using the Pablo UNIX I/O Analysis Tools: A Tutorial

The following standalone programs produce summaries of I/O activity by processing SDDF I/O event records from traces file generated by the I/O extension to the Pablo trace library:  To produce a report detailing UNIX I/O activity, analysts complete the following steps:

 

  1. If multiple SDDF trace files were produced, run MergePabloTraces to merge the data into one file. If multiple SDDF files were not produced, the file is already considered merged.

  2. Run SyncIOfileIDs   on the merged file to synchronize the file identifiers.

  3. Run the desired UNIX I/O analysis utilities on the output from SyncIOfileIDs to produce reports.

  4. Unix I/O Analysis Utilities

IOstatsTable generates a report, from detailed I/O trace records in the input SDDF trace file, containing two tables of information about application I/O activity, summarized by request type. This report provides a high-level depiction of overall I/O performance, revealing the nodes, operations, or code segments where performance was relatively poor. The information it contains enables analysts to quickly identify where to look for bottlenecks. By default, the necessary trace event records are produced by the I/O extension to the Pablo trace library whenever the I/O extension has been initialized and individual I/O calls have been instrumented.

As IOstatsTable is running, it periodically displays the number of input trace packets (records) processed to standard error. The report output is directed to standard out.

If the input file does not include any I/O detail trace records, the report will be generated without error but will contain all zeros. For the report to work as intended, there must be I/O detail trace records in the input SDDF file. If the programmer elects not to collect I/O detail trace records for the entire application execution, the report must be interpreted with that in mind.

IOstats generates a report of application I/O activity, summarized by I/O operation type from detailed I/O trace event records in the input SDDF trace file. The necessary trace event records are produced by the I/O extension to the Pablo trace library by default whenever the I/O extension has been initialized and individual I/O calls have been instrumented.

As IOstats is running, it periodically displays the number of input trace packets (records) processed to standard error. The report output is directed to standard out. Several paragraphs of text describing the report contents are included after the actual I/O activity information. If the input file does not include any I/O detail trace records, the report will be generated without error but will contain all zeros. For the report to work as intended, there must be I/O detail trace records in the input SDDF file. If the programmer elects not to collect I/O detail trace records for the entire application execution, the report must be interpreted with that in mind.

IOtotalsByPE generates a report showing the total count, duration, and bytes involved for various I/O operations by processor number from detailed I/O trace records in the input SDDF file. The necessary detail trace event records are produced by the I/O extension to the Pablo trace library by default whenever the I/O extension has been initialized and individual I/O calls have been instrumented.

As IOtotalsByPE is running, it periodically displays the number of input trace packets (records) processed to standard error. The report output is directed to standard out and is 132 characters wide.

If the input file does not include any detail I/O trace records, the report will be generated without error, but will contain all zeros.

System Requirements of the Pablo UNIX Analysis Tools
Download the Pablo Trace Library
Download A User's Guide to Pablo I/O Instrumentation
Download the Pablo UNIX I/O Library User Guide