hi all
has anybody got any information on ExSetTimerResolution function. it is not
documented in windows 2000 ddk.
can we use it.
does it allow a granularity of less than 10ms
regards
Mayank
See the documentation below…
ExSetTimerResolution
ExSetTimerResolution routine modifies the frequency at which the system
clock interrupts. Use this routine with extreme caution (see the following
Comments section).
ULONG
ExSetTimerResolution(
IN ULONG DesiredTime,
IN BOOLEAN SetResolution
);Parameters
DesiredTime
Specifies the amount of time that should elapse between each timer
interrupt, in 100 nanosecond units. The minimum value is approximately
10,000 (1 millisecond) but can vary slightly by platform. (This parameter is
ignored if SetResolution is FALSE.)
SetResolution
If TRUE, the call is a request to set the clock interrupt frequency to the
value specified by DesiredTime. If FALSE, the call is a request to restore
the clock interrupt frequency to the system’s default value, which is
platform-specific.
Include
wdm.h or ntddk.h
Return Value
ExSetTimerResolution returns the new timer resolution, in 100 nanosecond
units.
Comments
To set the timer resolution, a driver calls this routine passing TRUE as the
parameter for SetResolution. The following rules apply:
a… The routine changes the clock interrupt frequency only if the
specified DesiredTime value is less than the current setting.
b… If a driver requests a DesiredTime value that is greater than what is
currently set, the routine just returns the current setting.
c… If a driver requests a DesiredTime value that is less than the system
clock can support, the routine uses the smallest resolution the system can
support, and returns that value.
If you use this routine to change the clock interrupt frequency, your driver
must restore the default interrupt frequency, typically by calling:
ExSetTimerResolution (0, FALSE);before being unloaded. (If multiple drivers
have attempted to modify the clock interrupt frequency, the system does not
restore the default frequency until all of these drivers have called this
routine with a SetResolution value of FALSE.)
Note that the result of changing the clock interrupt frequency is
system-wide and can have a severely negative effect on system performance.
Also note that higher clock interrupt frequencies can shorten a system’s
battery life.
Callers of this routine must be running at IRQL < DISPATCH_LEVEL.
regards,
sujith
----- Original Message -----
From: “Mayank Kumar”
To: “NT Developers Interest List”
Sent: Thursday, May 15, 2003 9:48 AM
Subject: [ntdev] ExSetTimerResolution
> hi all
> has anybody got any information on ExSetTimerResolution function. it is
not
> documented in windows 2000 ddk.
> can we use it.
> does it allow a granularity of less than 10ms
>
> regards
> Mayank
>
>
>
>
> —
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