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SoftWare Interrupt Statistics ============================= Documentation for !SWIstat application version 2.01 01-May-1995 for RISC OS 3.1 and later. Issue: 2.01/T 17-Jun-1995, replaces: 0.10 21-Aug-1990 1.00 01-Sep-1990 1.00/R 21-Jun-1991 1.01/R 24-Apr-1992 1.50 05-Apr-1994 Author: David J Ruck Copyright © DEEJ Technology PLC 1990-1995 Overview ======== The !SWIstat application provides information on the activity of all SoftWare Interrupts (SWI's) occurring in your machine, the next best thing to Acorns own hardware debugging systems. It is intended for programmers who wish to debug or improve the efficiency of their application's or module's interface with the OS. It does this by showing exactly which software interrupt calls are being made, when and in what quantity. It can also be used by the merely incurably curious for a fascinating insight into what the computer is getting up to, and which are the most frequently used SWI's. Using !SWIstat ============== When started !SWIstat installs its own icon on the icon bar, clicking on it will display the main window. This window contains information on all the currently installed modules in the machine. Each module that provides SWI's has its own entry, giving its name and a value and a graphic display of this value, similar to the bars used in the Task manager's window. The value is either the total number of SWI calls handled by modules since the application was first installed in the machine, or the number of calls handled in a set time period. Switching between these displays is described in the !SWIstat menu section below. The Main Window The first entry in the window is the total value of all the entries below. The utility module SWI's have been split into two sections; the first for SWI's in the range 000000 Hex to 0000FF Hex and the second for OS_WriteI's from 000100 Hex to 0001FF Hex, All SWI's referred to include the X form. Sub Windows Clicking on any of the module names (not the All SWI'S entry) will display a subwindow for that module. The contents of the window are similar to that of the main window, except that the number of calls (totals or per interval) for each SWI that the module provides are displayed. The first entry is the total for that module, as is displayed in the main window. Each of the windows for the two Utility module sections have 256 entries, other modules have up to 64, but only SWI's which the module provides names for are displayed. The names in the subwindows are the names of the SWI's that the module provides with module name prefix removed so that more of the name can be displayed. Counter Windows Clicking on the All SWI's entry in the main window or any entry in a subwindow will call up a counter window, (it resembles the X windows program xload). The counter window shows the number of SWI's (for an individual SWI or all SWI's in a module) occurring in the set interval, as a vertical line. The display scrolls to the left each interval to show a new value, thus the variation in activity of a SWI or module can be monitored over a period of time. It is easier to see sudden peaks of activity in a counter window than in the main and subwindows, which do not need to be open once a counter window has been called up. Any number of counter windows (memory permitting) can be active at once. The counter window display automatically scales up and down to fit the maximum value in the window. At the default scale 4 OS units (1 rectangular pixel) is equivalent to one call, each subsequent scale is half the last shown by the horizontal grey lines. These do not represent values but show how many times the height of the bars have been halved; e.g. 1 line = ½ scale, 2 lines = ¼ scale, 10 lines 1/1024th scale. Window menu ----------- The main window and all subwindows provide a menu, the entries are described below. Totals This affects the main window and all subwindows. When ticked the display of each window gives the total number of calls to each SWI or module since the program was first installed. The dark grey backed heading of each window will change to show; Total SWI calls since initialisation. Per interval This also affects the main window and all subwindows; it changes the displays to show the number of SWI calls in a given time interval, set by Update rate below. The headings change to SWI calls per rate (actual rate) ms. Where rate is the set rate and actual rate is the rate achieved, see below. Update rate The value entered into the writable sub menu determines the interval used when displaying in Per interval mode, and the update rate of counter windows, which always show the number of SWI's in this interval in both Totals and Per interval modes. The value entered is in milliseconds (1/1000th sec), due to RISC OS limitations it is only possible to set the rate to the nearest 10ms, a minimum of 100ms is imposed. When using large values it should be noted that the new value only comes into effect on the next scheduled update. If a lot of tasks are running or a number of subwindows or counter windows are open it may not be possible for the program to update its displays at very high rates, this is automatically taken into account, and the values and sizes of bars are corrected accordingly. Scale Bars in the main and subwindows are automatically scaled to fit the largest in the window by default, this can however, lead to the bars for small values disappearing. Clicking on the Scale option on the main menu toggles automatic and manual scaling, which is shown by a tick next to scale. When using manual scaling values can be entered in the writable submenu, the top entry multiplies the size of the bar, and the bottom entry divides it. Some multipliers are not allowed when values becomes very large, to prevent integer overflow. Tasks !SWIstat monitors the SWI activity of all active RISC OS tasks as default. By using the task menu, the activity of a particular task can be monitored in isolation, by choosing it’s name from the task list. This makes it easier to scrutinise the calls made by a task which is currently under test. As !SWIstat must make a number of SWI calls itself in order to update the displays, the activity of all tasks Except !SWIstat can be shown using this option. The All Tasks entry will restore the default behaviour. Zero Counts This option will zero the counts for all SWI’s which can be seen when displaying totals. All counter windows are also cleared. This option can be used after changing the task being monitored using the Tasks menu described above. This will clear the totals so that only calls from the particular task are displayed subsequently. Iconbar menu ------------ Info Displays program information and version number. Display Displays the main window, equivalent to clicking on the !SWIstat icon. Reinit If you or an application install more SWI providing modules after the !SWIstat application has started, they will not be recognised unless the ReInit option is used. This resets the totals since initialisation to zero, closes all subwindows and counter windows, and re-displays the main window with the new modules. Kill Quits the application and kills the SWImod module which performs the counting of SWI’s. This ensures the small processing overhead imposed by the module is removed. Quit Quits the application, the SWImod module is not killed so if the program is run again, the SWI totals will still have been incremented while the program was not running, see Technical details below. Technical details ================= !SWIstat works by installing a special module SWImod which claims the SWI vector. The details below are provided for users who may wish to use this module in their own programs. On initialisation the SWImod module interrogates each module in turn to determine whether it provides SWI's, if it does a piece of RMA workspace is claimed to store the total number of calls to each SWI. It then claims the SWI vector and increments the correct value every time a SWI is called. The SWImod module is controlled using the following SWI’s. SWI_stat (&49080) !SWIstat uses this call every update interval to read the current SWI use counts, and calculate the correct values for the program displays. A call to SWI_stat (no parameters required) returns a pointer in R0 to a memory structure (type: main_str) which is described in C as: typedef struct { struct mod__str *chain_ptr; /* pointer to chain of mod_str */ int swi_total; /* total of all SWI’s called */ int totals[2]; /* total of 1st & 2nd 256 SWI’s */ int counts[512]; /* usage counts for 1st 512 SWI’s */ } main_str; typedef struct mod__str { struct mod__str *next_ptr; /* pointer to next in chain */ int chunk_no; /* chunk number of module */ int mod_total; /* total of all SWI’s by module */ char mod_name[24]; /* name of module */ int counts[64]; /* usage counts for 64 mod SWI’s */ } mod_str; SWI_Zero (&49081) Calling this routine causes all the SWI counts to be zeroed. Counting continues immediately. SWI_Control (&49082) This call is used to activate (R0 = 1) or suspend (R0 = 0) the modules counting activity. While suspended the SWI vector is still claimed, but computational overhead of the counting operation is removed. SWI_Filter (&49083) This call controls which tasks are monitored by SWImod. The value of R0 are R1 control the operation. R0 = 0 All tasks are monitored (default). R0 = 1 R1 = task handle to exclusively monitor. R0 = 2 R1 = task handle to exclude, i.e. monitor all except R1. The monitoring of tasks is performed using a WIMP post–filter mechanism, to enable or disable the counting of SWI’s depending on the task the WIMP has just switched in. Calls made by the operating system during a WIMP_Poll are assigned to the task which called it. !APPstat ======== Also from DEEJ Technology PLC is the companion application !APPstat. Using the same style of displays !APPstat provides microsecond accurate timing information on the amount of processing performed by each application. It is the best tool currently available to help programmers to see the results of optimising various parts of their programs, and to decide how much time should be spent in Idle processing, without being antisocial to other applications. It also provides information and timings on the event types and message action types from Wimp_Poll's which are currently being delivered to different tasks, so the parts of a program taking up execution time can be identified. End of SWIstat User Guide.