> Author: markj > Date: Thu Mar 21 02:52:22 2019 > New Revision: 345359 > URL: https://svnweb.freebsd.org/changeset/base/345359 > > Log: > 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.
"May" is the important aspect here, and to my knowledge both bhyve and Vmware provide a way to pin cpus there should be a way for us to turn this back on if it is desired. Sticking it under the big knob vm_guest is probably not the most flexiable solution. Could we please have someway to force this back on? > > PR: 218452 > MFC after: 2 weeks > Sponsored by: The FreeBSD Foundation > > Modified: > head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c > head/sys/cddl/dev/dtrace/i386/dtrace_subr.c > > Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c > ============================================================================== > --- head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Thu Mar 21 01:16:37 > 2019 (r345358) > +++ head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Thu Mar 21 02:52:22 > 2019 (r345359) > @@ -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; > > Modified: head/sys/cddl/dev/dtrace/i386/dtrace_subr.c > ============================================================================== > --- head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Thu Mar 21 01:16:37 > 2019 (r345358) > +++ head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Thu Mar 21 02:52:22 > 2019 (r345359) > @@ -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; > > -- Rod Grimes [email protected] _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "[email protected]"
