Re: [Xen-devel] [PATCH 4/5] x86/time: refactor read_platform_stime()

[Joao Martins <joao.m.martins@xxxxxxxxxx>]

On 03/18/2016 08:34 PM, Andrew Cooper wrote:
> On 17/03/16 16:12, Joao Martins wrote:
>> To fetch the last read from the clocksource which was used to
>> calculate system_time. In the case of clocksource=tsc we will
>> use it to set tsc_timestamp.
>>
>> Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
> 
> Again, just minor style issues.
> 
> Reviewed-by Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
All fixed, though I found one change missing in this series, specifically on
time_calibration_std_rendezvous. Otherwise this commit would break compilation.
See chunk below for the change I am adding:

@@ -1377,7 +1380,7 @@ 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);
         mb(); /* write r->master_stime /then/ signal */
         atomic_inc(&r->semaphore);
     }

Having this fixed, could I still keep your Reviewed-by?

>> ---
>> Cc: Keir Fraser <keir@xxxxxxx>
>> Cc: Jan Beulich <jbeulich@xxxxxxxx>
>> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>> ---
>>  xen/arch/x86/time.c | 16 ++++++++++------
>>  1 file changed, 10 insertions(+), 6 deletions(-)
>>
>> diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
>> index 5af8902..89c35d0 100644
>> --- a/xen/arch/x86/time.c
>> +++ b/xen/arch/x86/time.c
>> @@ -508,6 +508,7 @@ static s_time_t stime_platform_stamp; /* System time at 
>> below platform time */
>>  static u64 platform_timer_stamp;      /* Platform time at above system time 
>> */
>>  static u64 plt_stamp64;          /* 64-bit platform counter stamp           
>> */
>>  static u64 plt_stamp;            /* hardware-width platform counter stamp   
>> */
>> +static u64 plt_stamp_counter;    /* last read since read_counter */
> 
> This can have its scope reduced to within read_platform_stime()
> 
>>  static struct timer plt_overflow_timer;
>>  
>>  static s_time_t __read_platform_stime(u64 platform_time)
>> @@ -566,7 +567,7 @@ 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;
>>      s_time_t stime;
>> @@ -574,8 +575,11 @@ static s_time_t read_platform_stime(void)
>>      ASSERT(!local_irq_is_enabled());
>>  
>>      spin_lock(&platform_timer_lock);
>> -    count = plt_stamp64 + ((plt_src.read_counter() - plt_stamp) & plt_mask);
>> +    plt_stamp_counter = plt_src.read_counter();
>> +    count = plt_stamp64 + ((plt_stamp_counter - plt_stamp) & plt_mask);
>>      stime = __read_platform_stime(count);
>> +    if (stamp)
> 
> Spaces.
> 
> ~Andrew
> 

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