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| author | Mark Johnston <markj@FreeBSD.org> | 2019-03-21 02:52:22 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2019-03-21 02:52:22 +0000 |
| commit | e362e590f90a1a3d03e9a78f6fe1b314d0a34402 (patch) | |
| tree | c988557be2084e8a1a164b0a31bbe1a37f6f9c6d /sys/cddl | |
| parent | 5ee81b26a8494eaa2424d861e2bfbd61b6799d3f (diff) | |
| download | src-e362e590f90a1a3d03e9a78f6fe1b314d0a34402.tar.gz src-e362e590f90a1a3d03e9a78f6fe1b314d0a34402.zip | |
Don't attempt to measure TSC skew when running as a VM guest.
It simply doesn't work in general since VCPUs may migrate between
physical cores. The approach used to measure skew also doesn't
make much sense in a VM.
PR: 218452
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Notes
Notes:
svn path=/head/; revision=345359
Diffstat (limited to 'sys/cddl')
| -rw-r--r-- | sys/cddl/dev/dtrace/amd64/dtrace_subr.c | 3 | ||||
| -rw-r--r-- | sys/cddl/dev/dtrace/i386/dtrace_subr.c | 3 |
2 files changed, 6 insertions, 0 deletions
diff --git a/sys/cddl/dev/dtrace/amd64/dtrace_subr.c b/sys/cddl/dev/dtrace/amd64/dtrace_subr.c index e080bd66066e..d898319e80c6 100644 --- a/sys/cddl/dev/dtrace/amd64/dtrace_subr.c +++ b/sys/cddl/dev/dtrace/amd64/dtrace_subr.c @@ -319,6 +319,9 @@ dtrace_gethrtime_init(void *arg) int i; #endif + if (vm_guest) + return; + /* The current CPU is the reference one. */ sched_pin(); tsc_skew[curcpu] = 0; diff --git a/sys/cddl/dev/dtrace/i386/dtrace_subr.c b/sys/cddl/dev/dtrace/i386/dtrace_subr.c index 47dbd6aaf321..fe6ea19ddb15 100644 --- a/sys/cddl/dev/dtrace/i386/dtrace_subr.c +++ b/sys/cddl/dev/dtrace/i386/dtrace_subr.c @@ -321,6 +321,9 @@ dtrace_gethrtime_init(void *arg) int i; #endif + if (vm_guest) + return; + /* The current CPU is the reference one. */ sched_pin(); tsc_skew[curcpu] = 0; |