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MFC 1.12:

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- Add entry about using timecounter TSC and cpu frequency changing.

Approved by:	re (scottl)
This commit is contained in:
mnag 2006-03-05 00:00:57 +00:00
parent e70f9bb8b0
commit b5e6e41da9
1 changed files with 8 additions and 0 deletions
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8
share/man/man4/cpufreq.4
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@ -72,6 +72,14 @@ If this occurs, the original values will be restored once the condition
has passed (e.g., the system has cooled sufficiently).
If a sysctl cannot be set due to an override condition, it will return
.Er EPERM .
.Pp
The frequency cannot be changed if TSC is in use as the timecounter.
This is because the timecounter system needs to use a source that has a
constant rate. The timecounter source can be changed with the
.Pa kern.timecounter.hardware
sysctl. Available modes are in
.Pa kern.timecounter.choice
sysctl entry.
.Bl -tag -width indent
.It Va dev.cpu.%d.freq
Current active CPU frequency in MHz.