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| author | mnag <mnag@FreeBSD.org> | 2006-03-03 02:04:52 +0000 |
|---|---|---|
| committer | mnag <mnag@FreeBSD.org> | 2006-03-03 02:04:52 +0000 |
| commit | e002770955f973e2bb101375d1257b501ad0fcd1 (patch) | |
| tree | 8f17ae3a971070f5716e458b7638b5de2dde75bf /share | |
| parent | 17ff680bcce3d081799af4532c150e79f745cdca (diff) | |
| download | FreeBSD-src-e002770955f973e2bb101375d1257b501ad0fcd1.zip FreeBSD-src-e002770955f973e2bb101375d1257b501ad0fcd1.tar.gz | |
- Add entry about using timecounter TSC and cpu frequency changing.
Approved by: njl
MFC after: 1 day
Diffstat (limited to 'share')
| -rw-r--r-- | share/man/man4/cpufreq.4 | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/share/man/man4/cpufreq.4 b/share/man/man4/cpufreq.4 index 05b35d7..8781542 100644 --- a/share/man/man4/cpufreq.4 +++ b/share/man/man4/cpufreq.4 @@ -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. |
