Since we'd like the updates to be done as synchronously as possible, make an attempt at yielding immediately after the TSC write.
Signed-off-by: Jan Beulich <[email protected]> --- v4: New. --- a/xen/arch/x86/time.c +++ b/xen/arch/x86/time.c @@ -1708,7 +1708,14 @@ static void time_calibration_tsc_rendezv atomic_inc(&r->semaphore); if ( i == 0 ) + { write_tsc(master_tsc); + /* + * Try to give our hyperthread(s), if any, a chance to do + * the same as instantly as possible. + */ + cpu_relax(); + } while ( atomic_read(&r->semaphore) != (2*total_cpus - 1) ) cpu_relax(); @@ -1730,7 +1737,14 @@ static void time_calibration_tsc_rendezv } if ( i == 0 ) + { write_tsc(master_tsc); + /* + * Try to give our hyperthread(s), if any, a chance to do + * the same as instantly as possible. + */ + cpu_relax(); + } atomic_inc(&r->semaphore); while ( atomic_read(&r->semaphore) > total_cpus )
