Re: [PATCH v7 1/6] x86/tsc: remove tsc_disabled flag

[Pavel Tatashin]

>
> IMO, we already have a message by
>
> mark_tsc_unstable("boot parameter notsc");
>
> and we will use 'notsc' in case of CONFIG_X86_TSC = no
>
> So, I guess there is no need to print this msg.
>

OK, removed the warning.

Re: [PATCH v7 1/6] x86/tsc: remove tsc_disabled flag

[Pavel Tatashin]

>
> IMO, we already have a message by
>
> mark_tsc_unstable("boot parameter notsc");
>
> and we will use 'notsc' in case of CONFIG_X86_TSC = no
>
> So, I guess there is no need to print this msg.
>

OK, removed the warning.

Re: [PATCH v7 1/6] x86/tsc: remove tsc_disabled flag

[Dou Liyang]

Hi Pavel,

At 11/03/2017 10:23 PM, Pavel Tatashin wrote:

Hi Dou,

Sure, I can remove the warning, but I think we should print something
that is indicating that notsc is not a good parameter anymore: i.e
tsc=unstable is better. Perhaps something like:
"Kernel parameter \'notsc\'  is deprecated, please use
\'tsc=unstable\' instead" ?



IMO, we already have a message by

mark_tsc_unstable("boot parameter notsc");

and we will use 'notsc' in case of CONFIG_X86_TSC = no

So, I guess there is no need to print this msg.

Thanks,
dou.


Pasha

Re: [PATCH v7 1/6] x86/tsc: remove tsc_disabled flag

[Dou Liyang]

Hi Pavel,

At 11/03/2017 10:23 PM, Pavel Tatashin wrote:

Hi Dou,

Sure, I can remove the warning, but I think we should print something
that is indicating that notsc is not a good parameter anymore: i.e
tsc=unstable is better. Perhaps something like:
"Kernel parameter \'notsc\'  is deprecated, please use
\'tsc=unstable\' instead" ?



IMO, we already have a message by

mark_tsc_unstable("boot parameter notsc");

and we will use 'notsc' in case of CONFIG_X86_TSC = no

So, I guess there is no need to print this msg.

Thanks,
dou.


Pasha

Re: [PATCH v7 1/6] x86/tsc: remove tsc_disabled flag

[Pavel Tatashin]

Hi Dou,

Sure, I can remove the warning, but I think we should print something
that is indicating that notsc is not a good parameter anymore: i.e
tsc=unstable is better. Perhaps something like:
"Kernel parameter \'notsc\'  is deprecated, please use
\'tsc=unstable\' instead" ?

Pasha

On Thu, Nov 2, 2017 at 9:58 PM, Dou Liyang  wrote:
> Hi Pavel,
>
>
> At 11/03/2017 01:26 AM, Pavel Tatashin wrote:
>>
>> tsc_disabled is set when notsc is passed as kernel parameter. The reason
>> we
>> have notsc is to avoid timing problems on multi-preccors systems. However,
>> we already have a mechanism to detect and resolve these issues by invoking
>> tsc unstable path.
>>
>> Signed-off-by: Pavel Tatashin 
>> ---
>>  arch/x86/kernel/tsc.c | 17 +++--
>>  1 file changed, 3 insertions(+), 14 deletions(-)
>>
>> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
>> index 796d96bb0821..1c4502a2b7b2 100644
>> --- a/arch/x86/kernel/tsc.c
>> +++ b/arch/x86/kernel/tsc.c
>> @@ -37,11 +37,6 @@ EXPORT_SYMBOL(tsc_khz);
>>   */
>>  static int __read_mostly tsc_unstable;
>>
>> -/* native_sched_clock() is called before tsc_init(), so
>> -   we must start with the TSC soft disabled to prevent
>> -   erroneous rdtsc usage on !boot_cpu_has(X86_FEATURE_TSC) processors */
>> -static int __read_mostly tsc_disabled = -1;
>> -
>>  static DEFINE_STATIC_KEY_FALSE(__use_tsc);
>>
>>  int tsc_clocksource_reliable;
>> @@ -248,7 +243,7 @@ EXPORT_SYMBOL_GPL(check_tsc_unstable);
>>  int __init notsc_setup(char *str)
>>  {
>> pr_warn("Kernel compiled with CONFIG_X86_TSC, cannot disable TSC
>> completely\n");
>
>
> IMO, this warning may make users confused, could we remove it from here?
>
> Thanks,
> dou.
>
>

Re: [PATCH v7 1/6] x86/tsc: remove tsc_disabled flag

[Pavel Tatashin]

Hi Dou,

Sure, I can remove the warning, but I think we should print something
that is indicating that notsc is not a good parameter anymore: i.e
tsc=unstable is better. Perhaps something like:
"Kernel parameter \'notsc\'  is deprecated, please use
\'tsc=unstable\' instead" ?

Pasha

On Thu, Nov 2, 2017 at 9:58 PM, Dou Liyang  wrote:
> Hi Pavel,
>
>
> At 11/03/2017 01:26 AM, Pavel Tatashin wrote:
>>
>> tsc_disabled is set when notsc is passed as kernel parameter. The reason
>> we
>> have notsc is to avoid timing problems on multi-preccors systems. However,
>> we already have a mechanism to detect and resolve these issues by invoking
>> tsc unstable path.
>>
>> Signed-off-by: Pavel Tatashin 
>> ---
>>  arch/x86/kernel/tsc.c | 17 +++--
>>  1 file changed, 3 insertions(+), 14 deletions(-)
>>
>> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
>> index 796d96bb0821..1c4502a2b7b2 100644
>> --- a/arch/x86/kernel/tsc.c
>> +++ b/arch/x86/kernel/tsc.c
>> @@ -37,11 +37,6 @@ EXPORT_SYMBOL(tsc_khz);
>>   */
>>  static int __read_mostly tsc_unstable;
>>
>> -/* native_sched_clock() is called before tsc_init(), so
>> -   we must start with the TSC soft disabled to prevent
>> -   erroneous rdtsc usage on !boot_cpu_has(X86_FEATURE_TSC) processors */
>> -static int __read_mostly tsc_disabled = -1;
>> -
>>  static DEFINE_STATIC_KEY_FALSE(__use_tsc);
>>
>>  int tsc_clocksource_reliable;
>> @@ -248,7 +243,7 @@ EXPORT_SYMBOL_GPL(check_tsc_unstable);
>>  int __init notsc_setup(char *str)
>>  {
>> pr_warn("Kernel compiled with CONFIG_X86_TSC, cannot disable TSC
>> completely\n");
>
>
> IMO, this warning may make users confused, could we remove it from here?
>
> Thanks,
> dou.
>
>

Re: [PATCH v7 1/6] x86/tsc: remove tsc_disabled flag

[Dou Liyang]

Hi Pavel,

At 11/03/2017 01:26 AM, Pavel Tatashin wrote:

tsc_disabled is set when notsc is passed as kernel parameter. The reason we
have notsc is to avoid timing problems on multi-preccors systems. However,
we already have a mechanism to detect and resolve these issues by invoking
tsc unstable path.

Signed-off-by: Pavel Tatashin 
---
 arch/x86/kernel/tsc.c | 17 +++--
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 796d96bb0821..1c4502a2b7b2 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -37,11 +37,6 @@ EXPORT_SYMBOL(tsc_khz);
  */
 static int __read_mostly tsc_unstable;

-/* native_sched_clock() is called before tsc_init(), so
-   we must start with the TSC soft disabled to prevent
-   erroneous rdtsc usage on !boot_cpu_has(X86_FEATURE_TSC) processors */
-static int __read_mostly tsc_disabled = -1;
-
 static DEFINE_STATIC_KEY_FALSE(__use_tsc);

 int tsc_clocksource_reliable;
@@ -248,7 +243,7 @@ EXPORT_SYMBOL_GPL(check_tsc_unstable);
 int __init notsc_setup(char *str)
 {
pr_warn("Kernel compiled with CONFIG_X86_TSC, cannot disable TSC 
completely\n");


IMO, this warning may make users confused, could we remove it from here?

Thanks,
dou.

Re: [PATCH v7 1/6] x86/tsc: remove tsc_disabled flag

[Dou Liyang]

Hi Pavel,

At 11/03/2017 01:26 AM, Pavel Tatashin wrote:

tsc_disabled is set when notsc is passed as kernel parameter. The reason we
have notsc is to avoid timing problems on multi-preccors systems. However,
we already have a mechanism to detect and resolve these issues by invoking
tsc unstable path.

Signed-off-by: Pavel Tatashin 
---
 arch/x86/kernel/tsc.c | 17 +++--
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 796d96bb0821..1c4502a2b7b2 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -37,11 +37,6 @@ EXPORT_SYMBOL(tsc_khz);
  */
 static int __read_mostly tsc_unstable;

-/* native_sched_clock() is called before tsc_init(), so
-   we must start with the TSC soft disabled to prevent
-   erroneous rdtsc usage on !boot_cpu_has(X86_FEATURE_TSC) processors */
-static int __read_mostly tsc_disabled = -1;
-
 static DEFINE_STATIC_KEY_FALSE(__use_tsc);

 int tsc_clocksource_reliable;
@@ -248,7 +243,7 @@ EXPORT_SYMBOL_GPL(check_tsc_unstable);
 int __init notsc_setup(char *str)
 {
pr_warn("Kernel compiled with CONFIG_X86_TSC, cannot disable TSC 
completely\n");


IMO, this warning may make users confused, could we remove it from here?

Thanks,
dou.