diff options
| author | cinap_lenrek <cinap_lenrek@gmx.de> | 2013-06-19 20:56:01 +0200 |
|---|---|---|
| committer | cinap_lenrek <cinap_lenrek@gmx.de> | 2013-06-19 20:56:01 +0200 |
| commit | 8da4c8dcde68ca1da9b131cfcea917e781abf768 (patch) | |
| tree | 8e0a82f94646b093317cc66f73999ad30a2d887e | |
| parent | 35314ce1e79a145c29ef83d2abdc823961b3653c (diff) | |
plan9.ini: add *notsc= option to disable use of TSC as righ resolution clock
we previously used tsc only on cpu kernel. now that
we use it on terminal kernel too, there might be some
surprises ahead.
so make it possible to disable tsc for machines where
the tsc rate is not kept constant across cores or is
dynamically adjusted by power management.
| -rw-r--r-- | sys/man/8/plan9.ini | 5 | ||||
| -rw-r--r-- | sys/src/9/pc/devarch.c | 2 |
2 files changed, 6 insertions, 1 deletions
diff --git a/sys/man/8/plan9.ini b/sys/man/8/plan9.ini index 61115f7fd..48aab7f37 100644 --- a/sys/man/8/plan9.ini +++ b/sys/man/8/plan9.ini @@ -720,6 +720,11 @@ processors. Prints a summary of the multiprocessor APIC interrupt configuration. .SS \fL*nomsi=\fP Disables message signaled interrupts. +.SS \fL*notsc=\fP +Disables the use of the per processor timestamp counter registers +as high resolution clock. This option is intended for machines where +the timestamp counter rate is not constant across cores or is adjusted +dynamically by power management. .SS \fL*pcimaxbno=value\fP This puts a limit on the maximum bus number probed on a PCI bus (default 7). diff --git a/sys/src/9/pc/devarch.c b/sys/src/9/pc/devarch.c index be29eab3c..90cc2f4b9 100644 --- a/sys/src/9/pc/devarch.c +++ b/sys/src/9/pc/devarch.c @@ -797,7 +797,7 @@ cpuidentify(void) /* * if there is one, set tsc to a known value */ - if(m->cpuiddx & Tsc){ + if((m->cpuiddx & Tsc) != 0 && getconf("*notsc") == nil){ m->havetsc = 1; cycles = _cycles; if(m->cpuiddx & Cpumsr) |