Intel IXP400 manual Event-Based Sampling, Iii. Print out the first five elements

Intel® IXP400 Software

Access-Layer Components: Performance Profiling (IxPerfProfAcc) API

iii.Print out the first five elements:

for (i=0; i++; i<5)

{

printf("timeprofile element %d pc value = 0x%x\n", i, timeProfile[i].programCounter); printf("timeprofile element %d freq value = %d\n", i, timeProfile[i].freq);

}

These profile results show the places in the user’s code that are most frequently being executed and that are taking up the most processor cycles.

The results for time sampling are also automatically written to a file when the “Stop” functions for these features are called. For vxWorks, this file is stored in the location pointed by the FTP server where the image for the system is downloaded from. In Linux, the file is stored in the /proc filesystem. As this filesystem is temporary, the user is required to copy the output file into a permanent location or else the results will be lost when a new round of sampling is done or when the system is stopped or rebooted. Sample file output for vxWorks is as follows:

Hits	Percent	PC Address	Symbol Address	Offset	ClosestRoutine
-------	---------	-------------	------------------	--------	-------------------
65451	99.8718	49a88	49914	174	reschedule
14	0.0214	47938	47924	14	intUnlock
10	0.0153	49a84	49914	170	reschedule
10	0.0153	49a8c	49914	178	reschedule
1	0.0015	54ab8	54ab8	0	__div32

Linux output is identical with the exception of the Percent column. In Linux, the user is also able to change the accuracy of matching the PC Address to the Symbol Address. The greater the accuracy required, the longer it takes to find a match. The recommended accuracy is 0xffff which means the module will reduce the PC Address by up to 0xffff until it can find a match. Else, a message is logged and “No symbol found” is written to the file. The accuracy can be changed by modifying the #define IX_PERFPROF_ACC_XSCALE_PMU_SYMBOL_ACCURACY.

The output filename is defined in IxPerfProfAcc. To use a different filename, the user is required to change the filename in the stop function for vxWorks or the ixPerfProfAccXscalePmuTimeSampCreateProcFile() function in Linux.

Note: The Linux proc file create API is declared public so that it can be called by the /proc file system. It should never be called directly by the user.

17.10.1.3Event-Based Sampling

This utility can be used to profile the user’s code through event sampling. The process is similar to that of time sampling. However, this utility tells the user which lines of codes trigger occurrences of the events specified by the user. The sampling rate is defined by the user and is the number of events before a sample is taken. Each event defined, may have its own sampling rate.

Programmer’s Guide	IXP400 Software Version 2.0	April 2005
	Document Number: 252539, Revision: 007	257