| Message ID | 1473874670-4986-4-git-send-email-joao.m.martins@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
>>> On 14.09.16 at 19:37, <joao.m.martins@oracle.com> wrote: > To allow the caller to fetch the last read from the clocksource which > was used to calculate system_time. This is a prerequisite for a > subsequent patch that will use this last read. > > Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Acked-by: Jan Beulich <jbeulich@suse.com> with one further minor request: > --- a/xen/arch/x86/time.c > +++ b/xen/arch/x86/time.c > @@ -581,18 +581,22 @@ static void plt_overflow(void *unused) > set_timer(&plt_overflow_timer, NOW() + plt_overflow_period); > } > > -static s_time_t read_platform_stime(void) > +static s_time_t read_platform_stime(u64 *stamp) > { > - u64 count; > + u64 plt_counter, count; > s_time_t stime; > > ASSERT(!local_irq_is_enabled()); > > spin_lock(&platform_timer_lock); > - count = plt_stamp64 + ((plt_src.read_counter() - plt_stamp) & plt_mask); > + plt_counter = plt_src.read_counter(); > + count = plt_stamp64 + ((plt_counter - plt_stamp) & plt_mask); > stime = __read_platform_stime(count); > spin_unlock(&platform_timer_lock); > > + if ( stamp ) > + *stamp = plt_counter; Considering that all current callers pass in NULL and you mean to add only one (iirc) which doesn't, please add unlikely() here. Jan
On 09/19/2016 11:15 AM, Jan Beulich wrote: >>>> On 14.09.16 at 19:37, <joao.m.martins@oracle.com> wrote: >> To allow the caller to fetch the last read from the clocksource which >> was used to calculate system_time. This is a prerequisite for a >> subsequent patch that will use this last read. >> >> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> > > Acked-by: Jan Beulich <jbeulich@suse.com> > with one further minor request: > >> --- a/xen/arch/x86/time.c >> +++ b/xen/arch/x86/time.c >> @@ -581,18 +581,22 @@ static void plt_overflow(void *unused) >> set_timer(&plt_overflow_timer, NOW() + plt_overflow_period); >> } >> >> -static s_time_t read_platform_stime(void) >> +static s_time_t read_platform_stime(u64 *stamp) >> { >> - u64 count; >> + u64 plt_counter, count; >> s_time_t stime; >> >> ASSERT(!local_irq_is_enabled()); >> >> spin_lock(&platform_timer_lock); >> - count = plt_stamp64 + ((plt_src.read_counter() - plt_stamp) & plt_mask); >> + plt_counter = plt_src.read_counter(); >> + count = plt_stamp64 + ((plt_counter - plt_stamp) & plt_mask); >> stime = __read_platform_stime(count); >> spin_unlock(&platform_timer_lock); >> >> + if ( stamp ) >> + *stamp = plt_counter; > > Considering that all current callers pass in NULL and you mean to > add only one (iirc) which doesn't, please add unlikely() here. OK, I will add it, Thank you! Joao
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c index e5001d5..af9e31f 100644 --- a/xen/arch/x86/time.c +++ b/xen/arch/x86/time.c @@ -581,18 +581,22 @@ static void plt_overflow(void *unused) set_timer(&plt_overflow_timer, NOW() + plt_overflow_period); } -static s_time_t read_platform_stime(void) +static s_time_t read_platform_stime(u64 *stamp) { - u64 count; + u64 plt_counter, count; s_time_t stime; ASSERT(!local_irq_is_enabled()); spin_lock(&platform_timer_lock); - count = plt_stamp64 + ((plt_src.read_counter() - plt_stamp) & plt_mask); + plt_counter = plt_src.read_counter(); + count = plt_stamp64 + ((plt_counter - plt_stamp) & plt_mask); stime = __read_platform_stime(count); spin_unlock(&platform_timer_lock); + if ( stamp ) + *stamp = plt_counter; + return stime; } @@ -726,7 +730,7 @@ void cstate_restore_tsc(void) if ( boot_cpu_has(X86_FEATURE_NONSTOP_TSC) ) return; - write_tsc(stime2tsc(read_platform_stime())); + write_tsc(stime2tsc(read_platform_stime(NULL))); } /*************************************************************************** @@ -1045,7 +1049,7 @@ int cpu_frequency_change(u64 freq) local_irq_disable(); /* Platform time /first/, as we may be delayed by platform_timer_lock. */ - t->stamp.master_stime = read_platform_stime(); + t->stamp.master_stime = read_platform_stime(NULL); curr_tsc = rdtsc_ordered(); /* TSC-extrapolated time may be bogus after frequency change. */ /*t->stamp.local_stime = get_s_time_fixed(curr_tsc);*/ @@ -1350,7 +1354,7 @@ static void time_calibration_tsc_rendezvous(void *_r) if ( r->master_stime == 0 ) { - r->master_stime = read_platform_stime(); + r->master_stime = read_platform_stime(NULL); r->master_tsc_stamp = rdtsc_ordered(); } atomic_inc(&r->semaphore); @@ -1390,7 +1394,7 @@ static void time_calibration_std_rendezvous(void *_r) { while ( atomic_read(&r->semaphore) != (total_cpus - 1) ) cpu_relax(); - r->master_stime = read_platform_stime(); + r->master_stime = read_platform_stime(NULL); smp_wmb(); /* write r->master_stime /then/ signal */ atomic_inc(&r->semaphore); } @@ -1429,7 +1433,7 @@ void time_latch_stamps(void) unsigned long flags; local_irq_save(flags); - ap_bringup_ref.master_stime = read_platform_stime(); + ap_bringup_ref.master_stime = read_platform_stime(NULL); ap_bringup_ref.local_tsc = rdtsc_ordered(); local_irq_restore(flags); @@ -1447,7 +1451,7 @@ void init_percpu_time(void) t->tsc_scale = per_cpu(cpu_time, 0).tsc_scale; local_irq_save(flags); - now = read_platform_stime(); + now = read_platform_stime(NULL); tsc = rdtsc_ordered(); local_irq_restore(flags);
To allow the caller to fetch the last read from the clocksource which was used to calculate system_time. This is a prerequisite for a subsequent patch that will use this last read. Signed-off-by: Joao Martins <joao.m.martins@oracle.com> --- Cc: Jan Beulich <jbeulich@suse.com> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Changes since v3: - Add mention of this being a prerequisite to a later patch. --- xen/arch/x86/time.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)