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#define INCL_DOSPROCESS
 
USHORT DosSetPrty(fScope, fPrtyClass, sChange, id)
USHORT fScope;        /* scope of change               */
USHORT fPrtyClass;    /* priority class to set         */
SHORT sChange;        /* change in priority level      */
USHORT id;            /* process or thread identifier  */
 
The DosSetPrty function sets the scheduling priority of the specified
process or thread by changing the priority class and/or the priority level.
 
Within each class, a thread's priority level may vary──either through system
action or through the DosSetPrty function. The system changes a thread's
priority level based on that thread's actions and the overall system
activity.
 
Parameter   Description
────────────────────────────────────────────────────────────────────────────
 
fScope      Specifies the scope of the request. This parameter can be one of
            the following values:
 
            Value              Meaning
            ────────────────────────────────────────────────────────────────
            PRTYS_PROCESS      Priority for the process and all its
                               threads.
 
            PRTYS_PROCESSTREE  Priority for the process and all its child
                               processes.
 
            PRTYS_THREAD       Priority for one thread in the current
                               process.
 
fPrtyClass  Specifies the priority class of a process or thread. This
            parameter can be one of the following values:
 
            Value               Meaning
            ────────────────────────────────────────────────────────────────
            PRTYC_IDLETIME      Idle time.
 
            PRTYC_NOCHANGE      No change; leave as is.
 
            PRTYC_REGULAR       Regular.
 
            PRTYC_FOREGROUND    Foreground server.
 
            PRTYC_TIMECRITICAL  Time-critical.
 
sChange     Specifies the relative change in the current priority level of
            the process or thread. This parameter can be any value from -31
            through +31, or the constants PRTYD_MINIMUM or PRTYD_MAXIMUM,
            which specify the minimum and maximum change allowed.
 
id          Specifies the process or thread identifier, depending on the
            value of the fScope parameter. If the value is a process
            identifier, it must be for the calling process or a child of the
            calling process. A value of zero can be used to specify the
            current thread or process.
 
Return Value
 
The return value is zero if the function is successful. Otherwise, it is an
error value, which may be one of the following:
 
     ERROR_INVALID_PCLASS
     ERROR_INVALID_PDELTA
     ERROR_INVALID_PROCID
     ERROR_INVALID_SCOPE
     ERROR_INVALID_THREADID
     ERROR_NOT_DESCENDANT
 
Comments
 
The PRTYC_FOREGROUND priority is higher than PRTYC_REGULAR, but lower than
PRTYC_TIMECRITICAL. PRTYC_FOREGROUND is a static priority that is not
changed by the system. This allows a thread or process in a background
screen group to service requests of a foreground process in a timely manner.
Because the priority level is static, this priority should be used only when
absolutely necessary. Indiscriminate use degrades system performance.
 
See Also
 
DosEnterCritSec, DosGetInfoSeg, DosGetPrty
 
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