diff mbox

[RFC,3/6] x86/time: streamline platform time init on plt_init()

Message ID 1451321985-13728-4-git-send-email-joao.m.martins@oracle.com (mailing list archive)
State New, archived
Headers show

Commit Message

Joao Martins Dec. 28, 2015, 4:59 p.m. UTC
And use to initialize platform time solely for clocksource=tsc,
as opposed to initializing platform overflow timer, which would
only fire in ~180 years (on 2.2 Ghz Broadwell processor).

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 xen/arch/x86/time.c | 41 +++++++++++++++++++++++++++++++++--------
 1 file changed, 33 insertions(+), 8 deletions(-)

Comments

Konrad Rzeszutek Wilk Jan. 25, 2016, 8:26 p.m. UTC | #1
> +    if ( clocksource_is_tsc )
> +    {
> +        plt_init();
> +    }
> +    else
> +    {
> +        plt_overflow_period = scale_delta(
> +            1ull << (pts->counter_bits-1), &plt_scale);
> +        init_timer(&plt_overflow_timer, plt_overflow, NULL, 0);
> +        plt_overflow(NULL);
> +
> +        printk("Platform timer overflow period is %lu secs\n",
> +               plt_overflow_period/1000000000);

s/1000000000/SECONDS(1) ?

> +    }
>  
>      platform_timer_stamp = plt_stamp64;
>      stime_platform_stamp = NOW();
> -- 
> 2.1.4
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
Joao Martins Jan. 26, 2016, 10:31 a.m. UTC | #2
On 01/25/2016 08:26 PM, Konrad Rzeszutek Wilk wrote:
>> +    if ( clocksource_is_tsc )
>> +    {
>> +        plt_init();
>> +    }
>> +    else
>> +    {
>> +        plt_overflow_period = scale_delta(
>> +            1ull << (pts->counter_bits-1), &plt_scale);
>> +        init_timer(&plt_overflow_timer, plt_overflow, NULL, 0);
>> +        plt_overflow(NULL);
>> +
>> +        printk("Platform timer overflow period is %lu secs\n",
>> +               plt_overflow_period/1000000000);
> 
> s/1000000000/SECONDS(1) ?
> 
Yeah, looks much better that way.

>> +    }
>>  
>>      platform_timer_stamp = plt_stamp64;
>>      stime_platform_stamp = NOW();
>> -- 
>> 2.1.4
>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xen.org
>> http://lists.xen.org/xen-devel
diff mbox

Patch

diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index c9e5c14..df42d31 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -518,17 +518,31 @@  static s_time_t __read_platform_stime(u64 platform_time)
     return (stime_platform_stamp + scale_delta(diff, &plt_scale));
 }
 
+static void __plt_init(void)
+{
+    u64 count;
+
+    ASSERT(spin_is_locked(&platform_timer_lock));
+    count = plt_src.read_counter();
+    plt_stamp64 += (count - plt_stamp) & plt_mask;
+    plt_stamp = count;
+}
+
+static void plt_init(void)
+{
+    spin_lock_irq(&platform_timer_lock);
+    __plt_init();
+    spin_unlock_irq(&platform_timer_lock);
+}
+
 static void plt_overflow(void *unused)
 {
     int i;
-    u64 count;
     s_time_t now, plt_now, plt_wrap;
 
     spin_lock_irq(&platform_timer_lock);
 
-    count = plt_src.read_counter();
-    plt_stamp64 += (count - plt_stamp) & plt_mask;
-    plt_stamp = count;
+    __plt_init();
 
     now = NOW();
     plt_wrap = __read_platform_stime(plt_stamp64);
@@ -635,11 +649,22 @@  static void __init init_platform_timer(void)
 
     set_time_scale(&plt_scale, pts->frequency);
 
-    plt_overflow_period = scale_delta(
-        1ull << (pts->counter_bits-1), &plt_scale);
-    init_timer(&plt_overflow_timer, plt_overflow, NULL, 0);
     plt_src = *pts;
-    plt_overflow(NULL);
+
+    if ( clocksource_is_tsc )
+    {
+        plt_init();
+    }
+    else
+    {
+        plt_overflow_period = scale_delta(
+            1ull << (pts->counter_bits-1), &plt_scale);
+        init_timer(&plt_overflow_timer, plt_overflow, NULL, 0);
+        plt_overflow(NULL);
+
+        printk("Platform timer overflow period is %lu secs\n",
+               plt_overflow_period/1000000000);
+    }
 
     platform_timer_stamp = plt_stamp64;
     stime_platform_stamp = NOW();