Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt

Jan Engelhardt
2005-07-14T09:29:41Z

>>>> "My expectation is if we want to beat the competition, we'll want
>>>> the ability to go *under* 100Hz."
>>>
>>> What does Windows do here?
>>
>> windows xp base rate is 100Hz... but multimedia apps can ask for almost
>
> 83Hz

Well, Windoes 98 (vmmon) shows very different ones:

/dev/vmmon[4355]: host clock rate change request 0 -> 19
/dev/vmmon[4355]: host clock rate change request 19 -> 0
/dev/vmmon[4355]: host clock rate change request 0 -> 19
/dev/vmmon[4355]: host clock rate change request 19 -> 63
/dev/vmmon[4355]: host clock rate change request 63 -> 200
/dev/vmmon[4355]: host clock rate change request 200 -> 201
/dev/vmmon[4355]: host clock rate change request 201 -> 1001

>> any rate they want (depends on the hw capabilities). i recall seeing
>> rates >1200Hz when you launch some of the media player apps -- sorry i
>> forget the exact number.

I have seen some apps which seem to schedule themselves using some kind of
SCHED_FIFO and therefore seem to get good RT:

from an ini file...
# This option determines the multi-tasking capabilities of WinDEU.
# The priority determines the minimum number of milliseconds WinDEU
# will work before giving control back to Windows.
# For example, if you set it to 20, it means WinDEU will gives
# back control to Windows approximately (at most) 50 times a second.
# A value of 0 means WinDEU WON'T multi-task.
# (Can be changed in the preferences dialog box.)
BuildPriority=25

Jan Engelhardt
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