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8.18 Performance profiler

A key issue in developing fast programs using the Monet database back-end requires a keen eye on where performance is lost. Although performance tracking and measurements are highly application dependent, a simple to use tool makes life a lot easier (See stethoscope and tomograph).

Activation of the performance monitor has a global effect, i.e. all concurrent actions on the kernel are traced, but the events are only sent to the client who initiated the profiler thread.

The profiler event can be handled in several ways. The default strategy is to ship the event record immediately over a stream to a performance monitor. An alternative strategy is preparation of off-line performance analysis, where event information is retained in tables.

To reduce the interference of performance measurement with the experiments, the user can use an event cache, which is emptied explicitly upon need.

module profiler;
pattern activate(name:str...):void
pattern deactivate(name:str...):void
pattern openStream():void
address CMDopenProfilerStream comment "Send the events to output stream";
pattern openStream(fnme:str):void
command closeStream():void
address CMDcloseProfilerStream comment "Stop sending the event records";
pattern setAll():void
pattern setFilter(v:any):void
address CMDsetFilterVariable comment "Generate an event record for every instruction where v is used."
pattern clrFilter(mod:str,fcn:str):void
pattern setStartPoint(mod:str,fcn:str):void
pattern start():void
address CMDstartProfiler comment "Start performance tracing";
command noop():void
pattern stop():void
address CMDstopProfiler comment "Stop performance tracing";
command reset():void
address CMDclearTrace comment "Clear the profiler traces";
command dumpTrace():void
command getTrace(e:str):bat[:int,:any_1]
address CMDgetTrace comment "Get the trace details of a specific event";
pattern getEvent()(:lng,:lng,:lng)
command cleanup():void
address CMDcleanup comment "Remove the temporary tables for profiling";
command getDiskReads():lng
address CMDgetDiskReads comment "Obtain the number of physical reads";
command getDiskWrites():lng
address CMDgetDiskWrites comment "Obtain the number of physical reads";
command getUserTime():lng
address CMDgetUserTime comment "Obtain the user timing information.";
command getSystemTime():lng
address CMDgetSystemTime comment "Obtain the user timing information.";
pattern getFootprint():lng