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Updated: 11 December 1998

OpenVMS System Services Reference Manual


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$SCHED

Affects process scheduling. This service is intended for use by a class scheduler process.

Format

SYS$SCHED func ,p1 ,p2 ,p3


C Prototype

int sys$sched (unsigned int func, unsigned int *p1, unsigned int *p2, unsigned int *p3);


Arguments

func


OpenVMS usage: function_code
type: longword (unsigned)
access: write only
mechanism: by value

Function code specifying the action $SCHED is to perform. The func argument is a longword containing this code.

See the Function Codes section for a list of valid function codes for $SCHED.

p1, p2, p3


OpenVMS usage: longword
type: longword (unsigned)
access: varies
mechanism: varies

The meaning of the p1, p2, and p3 arguments depends on the function code specified in the func argument, and is defined in the Function Codes section.
Function Codes This section defines each of the $SCHED function codes and describes the values of the p1 argument, p2 argument, and p3 argument for each function.

CSH$_READ_ALL

When you specify CSH$_READ_ALL, $SCHED returns a buffer containing information, including an index, EPID, and priority, for all processes.

The format of the buffer is defined in the $CSHDEF macro and consists of a series of CSHP fields.

The following table shows the p1 argument, p2 argument, and p3 argument values for the CSH$_READ_ALL function code.
Argument Access Description
p1 Read Address of the buffer.
p2 Read Address of the longword size of the buffer.
p3 Write Address of the longword size of the per-process entry.

CSH$_READ_NEW

When you specify CSH$_READ_NEW, $SCHED returns a buffer containing information, including an index, EPID, and priority, for all processes for which a class assignment has not been made.

The format of the buffer is defined in the $CSHDEF macro and consists of a series of CSHP fields.

The following table shows the p1 argument, p2 argument, and p3 argument values for the CSH$_READ_NEW function code.
Argument Access Description
p1 Read Address of the buffer.
p2 Read Address of the longword size of the buffer.
p3 Write Address of the longword size of the per-process entry.

The following table describes the information returned in the buffer fields for both CSH$_READ_ALL and CSH$_READ_NEW.
Buffer Field Definition
CSHP$T_ACCOUNT Account string from the user authorization file (first eight characters).
CSHP$L_CPUTIM Process CPU time used, in 10-millisecond ticks.
CSHP$L_EPID Process ID (PID). If CSHP information is insufficient to determine the right class for a process, the PID can be used with the $GETJPI(W) system service to obtain additional detail.
CSHP$W_PIX A unique integer assigned to the process for its duration. Applications might want to use this value to index arrays.
CSHP$B_PRI Current process priority.
CSHP$B_PRIB Base process priority.
CSHP$L_STATUS Undefined; reserved to Compaq.

CSH$_READ_QUANT

When you specify CSH$_READ_QUANT, $SCHED returns a buffer containing information about how many ticks are left for each class. Data is returned in a series of longwords, one longword per class, starting with class number 0.

The following table defines the p1 argument, p2 argument, and p3 argument values when specifying the CSH$_READ_QUANT function code.
Argument Access Description
p1 Read Address of the buffer.
p2 Read Address of the longword size of the buffer.
p3 --- Unused.

CSH$_SET_ATTN_AST

Enables attention asynchronous system traps (ASTs).

The following table defines the p1 argument, p2 argument, and p3 argument values when specifying the CSH$_SET_ATTN_AST function code.
Argument Access Description
p1 Read Address of an AST routine.
p2 Read Access mode to deliver AST.
p3 --- Unused.

CSH$_SET_CLASS

Places processes in classes with or without windfall capability. The caller supplies a buffer consisting of CSHC blocks.

The format of the buffer is defined in the $CSHDEF macro. The following table describes the information contained in the buffer.
Buffer Field Definition
CSHC$L_EPID Process ID (PID) of the process to affect.
CSHC$W_CLASS Class into which to place the process. Class 65535 (hexadecimal FFFF) has a special interpretation: the associated process is not to be class scheduled and will, therefore, never run out of class quantum. The largest class number is 8191.
CSHC$W_WINDFALL Determines whether the process is to share windfall. A value of 1 permits the process to share windfall; a value of 0 prevents the process from sharing windfall. Values other than 0 and 1 are undefined and can cause unpredictable behavior in future releases of the operating system.

The following table defines the p1 argument, p2 argument, and p3 argument values when specifying the CSH$_SET_CLASS function code.
Argument Access Description
p1 Read Address of the buffer.
p2 Read Address of the longword size of the buffer.
p3 Read Address of the longword size of the entry used. Should be CSHC$K_LENGTH or equivalent.

CSH$_SET_NEW

Indicates to the class scheduler that the next READ_NEW will return information about the calling process. This function should be used only in executive or kernel mode.

The following table defines the p1 argument, p2 argument, and p3 argument values when specifying the CSH$_SET_NEW function code.
Argument Access Description
p1 --- Unused.
p2 Read PID (by value).
p3 --- Unused.

CSH$_SET_QUANT

Establishes class quantum and enables class scheduling. The caller supplies a buffer that allocates CPU ticks to classes, one longword per class, starting with class number 0. Class-scheduled processes will have their quantum deducted from the appropriate longword, and will be removed from execution if class quantum is decremented to 0.

The following table defines the p1 argument, p2 argument, and p3 argument values when specifying the CSH$_SET_QUANT function code.
Argument Access Description
p1 Read Address of the buffer.
p2 Read Address of the longword size of buffer.
p3 --- Unused.

CSH$_SET_TIMEOUT

Establishes a nonstandard timeout. If the application does not issue a CSH$_SET_QUANT within the timeout period, all class scheduling is stopped and processes are returned to normal scheduling. The default value, 30 seconds, should be suitable for most circumstances.

The following table defines the p1 argument, p2 argument, and p3 argument values when specifying the CSH$_SET_TIMEOUT function code.
Argument Access Description
p1 --- Unused.
p2 Read Time in seconds (by value).
p3 --- Unused.


Description

The Affect Process Scheduling service is used by class scheduler processes to affect scheduling.

Use the func argument to specify which action $SCHED is to perform.

Required Access or Privileges

ALTPRI is required to affect processes. Group access is required to affect processes in the same UIC group. World access is required to affect processes in different UIC groups. SYSPRV is required to set the timeout value.

Required Quota

None

Related Services

$GETJPI, $GETJPIW, $SETPRI


Condition Values Returned

SS$_NORMAL The service completed successfully.
SS$_BADPARAM The function code is invalid.
SS$_ILLSER The loadable image CLASS_SCHEDULER has not been loaded. Refer to the SYSMAN command SYS_LOADABLE in the OpenVMS System Management Utilities Reference Manual for instructions.

$SETAST

Enables or disables the delivery of asynchronous system traps (ASTs) for the access mode from which the service call was issued.

Format

SYS$SETAST enbflg


C Prototype

int sys$setast (char enbflg);


Argument

enbflg


OpenVMS usage: boolean
type: byte (unsigned)
access: read only
mechanism: by value

Value specifying whether ASTs are to be enabled. The enbflg argument is a byte containing this value. The value 1 enables AST delivery for the calling access mode; the value 0 disables AST delivery.

Description

The Set AST Enable service enables or disables the delivery of ASTs for the access mode from which the service call was issued.

Required Access or Privileges

When an image is executing in user mode, ASTs are always enabled for more privileged access modes. If ASTs are disabled for a more privileged access mode, the operating system cannot deliver ASTs for less privileged access modes until ASTs are enabled once again for the more privileged access mode. Therefore, a process that has disabled ASTs for a more privileged access mode must reenable ASTs for that mode before returning to a less privileged access mode.

Required Quota

None

Related Services

$DCLAST, $SETPRA


Condition Values Returned

SS$_WASCLR The service completed successfully. AST delivery was previously disabled for the calling access mode.
SS$_WASSET The service completed successfully. AST delivery was previously enabled for the calling access mode.

$SETCLUEVT

Establishes a request for notification when an OpenVMS Cluster configuration event occurs.

Format

SYS$SETCLUEVT event ,astadr ,[astprm] ,[acmode] ,[handle]


C Prototype

int sys$setcluevt (unsigned int event, void (*astadr)(__unknown_params), int astprm, unsigned int acmode, struct _generic_64 *handle);


Arguments

event


OpenVMS usage: event_code
type: longword (unsigned)
access: read only
mechanism: by value

Event code indicating the type of cluster configuration event for which an AST is to be delivered. The event argument is a value indicating which type of event is of interest.

Each event type has a symbolic name. The $CLUEVTDEF macro defines the following symbolic names.
Symbolic Name Description
CLUEVT$C_ADD One or more OpenVMS nodes have been added to the OpenVMS Cluster system.
CLUEVT$C_REMOVE One or more OpenVMS nodes have been removed from the OpenVMS Cluster system.

astadr


OpenVMS usage: ast_procedure
type: procedure value
access: call without stack unwinding
mechanism: by reference

Notification AST routine to receive control after a change in OpenVMS Cluster configuration occurs.

astprm


OpenVMS usage: user_arg
type: longword (unsigned)
access: read only
mechanism: by value

Optional AST parameter to be passed to the AST service routine. The astprm argument is a longword value containing the AST parameter.

acmode


OpenVMS usage: access_mode
type: longword (unsigned)
access: read only
mechanism: by value

Optional access mode at which the configuration event AST is to execute. The acmode argument is a longword containing the access mode.

Each access mode has a symbolic name. The $PSLDEF macro defines the following symbols for the four access modes.
Symbol Access Mode
PSL$C_KERNEL Kernel
PSL$C_EXEC Executive
PSL$C_SUPER Supervisor
PSL$C_USER User

The value of the access mode must not be more privileged than the access mode of the caller.

handle


OpenVMS usage: identifier
type: quadword (unsigned)
access: write only
mechanism: by reference

Optional identifier to receive a value that uniquely identifies this AST request. $SETCLUEVT sets this handle to a unique value so that it can later be used to identify the request in the $CLRCLUEVT and $TSTCLUEVT services.

Description

The Set Cluster Event service establishes a request for notification when a cluster configuration event occurs. The service establishes only one AST notification for a configuration event. To receive AST notification for all cluster configuration events, the $SETCLUEVT service must be reissued within the notification AST routine. The service will verify that the input parameters specify a valid request, allocate appropriate data structures to hold the request, and enqueue the request for notification.

You must specify an event type and an AST address. You can specify an AST parameter, the access mode, and an address into which to place the handle of this request.

Errors will be returned in the following cases:

Required Access or Privileges

None

Required Quota

None

Related Services

$CLRCLUEVT, $TSTCLUEVT


Condition Values Returned

SS$_NORMAL The service completed successfully.
SS$_ACCVIO Unable to process parameters for improper use.
SS$_BADPARAM The event was improperly specified.
SS$_EXASTLM The process exceeded its quota for outstanding AST requests.
SS$_INSFMEM The system dynamic memory is insufficient to complete the service.

$SETDDIR

Allows you to read and change the default directory string for the process.

Format

SYS$SETDDIR [new-dir-addr] ,[length-addr] ,[cur-dir-addr]


C Prototype

int sys$setddir (void *newdiraddr, unsigned short int *lengthaddr, void *curdiraddr);


Arguments

new-dir-addr


OpenVMS usage: char_string
type: character-coded text string
access: read only
mechanism: by descriptor--fixed-length string descriptor

A descriptor of the new default directory. The new-dir-addr argument is the address of the descriptor that points to the buffer containing the new directory specification that RMS will use to set the new process-default directory. If the default directory is not to be changed, the value of the new-dir-addr argument should be 0.

length-addr


OpenVMS usage: word_unsigned
type: word (unsigned)
access: write only
mechanism: by reference

A word that is to receive the length of the current default directory. The length-addr argument is the address of the word that will receive the length. If you do not want this value returned, specify the value 0.

cur-dir-addr


OpenVMS usage: char_string
type: character-coded text string
access: write only
mechanism: by descriptor--fixed-length string descriptor

A descriptor of a buffer that is to receive the current default directory string. The cur-dir-addr argument is the address of the descriptor that points to the buffer area that is to receive the current directory string.

Description

The Set Default Directory service allows you to read and change the default directory string for the process. You should restore the previous default directory string to its original state unless you want the changed default directory string to last beyond the exit of your image. The new directory name string is checked for correct syntax.

There is no predefined macro of the form $SETDDIR_G or $SETDDIR_S to call this service.

On Alpha systems, the Set Default Directory service attempts to replace the default directory string with a DID abbreviation if the length of the resulting default directory exceeds 255 characters. If this happens, then in addition to the normal syntax check, the entire path to that specification, including the device, is verified and must exist for the call to succeed.

Required Access or Privileges

None

Required Quota

None

Related Services

$ALLOC, $ASSIGN, $BRKTHRU, $BRKTHRUW, $CANCEL, $CREMBX, $DALLOC, $DASSGN, $DELMBX, $DEVICE_SCAN, $DISMOU, $GETDVI, $GETDVIW, $GETMSG, $GETQUI, $GETQUIW, $INIT_VOL, $MOUNT, $PUTMSG, $QIO, $QIOW, $SNDERR, $SNDJBC, $SNDJBCW, $SNDOPR


Condition Values Returned

RMS$_NORMAL The service completed successfully.
RMS$_DIR The directory name contains an error.
RMS$_IAL The argument list is invalid.


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