Hi,
Sorry for the late review but here we go:
On 11/14/23 19:46, Bibo Mao wrote:
> When cpu is hotplug out, cpu is in idle state and function
"When a CPU is hot-unplugged, it is put into idle state and the function
... is called"
> arch_cpu_idle_dead is called. Timer interrupt for this processor should
> be disabled, else there will be timer interrupt for the dead cpu. Also
> this prevents vcpu to schedule out during halt-polling flow when system
> is running in vm mode, since there is pending timer interrupt.
The logical relationship is a bit unclear, is my paraphrasing correct in
your opinion?
"Timer interrupt for this processor should be disabled, else a pending
timer interrupt will prevent the vCPU from scheduling out during the
halt-polling flow when system is running in VM mode"
(I don't immediately know what a "schedule out" is. Is that a
translation artifact or some KVM jargon?)
>
> This patch adds detailed implementation for timer shutdown interface, so
> that timer will be disabled when cpu is plug-out.
Missing some definite articles too.
"This patch implements the timer shutdown interface so that the timer
will be properly disabled when a CPU is hot-unplugged"
Is this version better?
>
> Signed-off-by: Bibo Mao <[email protected]>
> ---
> arch/loongarch/kernel/time.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
> index 3064af94db9c..2920770e30a9 100644
> --- a/arch/loongarch/kernel/time.c
> +++ b/arch/loongarch/kernel/time.c
> @@ -58,7 +58,7 @@ static int constant_set_state_oneshot(struct clock_event_device *evt)
> return 0;
> }
>
> -static int constant_set_state_oneshot_stopped(struct clock_event_device *evt)
> +static int constant_set_state_shutdown(struct clock_event_device *evt)
> {
> unsigned long timer_config;
>
> @@ -90,11 +90,6 @@ static int constant_set_state_periodic(struct clock_event_device *evt)
> return 0;
> }
>
> -static int constant_set_state_shutdown(struct clock_event_device *evt)
> -{
> - return 0;
> -}
> -
> static int constant_timer_next_event(unsigned long delta, struct clock_event_device *evt)
> {
> unsigned long timer_config;
> @@ -161,7 +156,7 @@ int constant_clockevent_init(void)
> cd->rating = 320;
> cd->cpumask = cpumask_of(cpu);
> cd->set_state_oneshot = constant_set_state_oneshot;
> - cd->set_state_oneshot_stopped = constant_set_state_oneshot_stopped;
> + cd->set_state_oneshot_stopped = constant_set_state_shutdown;
> cd->set_state_periodic = constant_set_state_periodic;
> cd->set_state_shutdown = constant_set_state_shutdown;
> cd->set_next_event = constant_timer_next_event;
>
> base-commit: 9bacdd8996c77c42ca004440be610692275ff9d0
Otherwise LGTM (regarding the renaming of
constant_set_state_oneshot_stopped, both it and the removed
constant_set_state_shutdown only has one usage respectively, and looking
at the function body it's arguably more appropriate to let it take the
"shutdown" name: it's just clearing the enable bit from the CSR.TCFG and
nothing else).
With the nits addressed:
Reviewed-by: WANG Xuerui <[email protected]>
--
WANG "xen0n" Xuerui
Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/
Xuerui,
Thanks for reviewing my patch, and I reply inline.
On 2023/11/16 下午3:09, WANG Xuerui wrote:
> Hi,
>
> Sorry for the late review but here we go:
>
> On 11/14/23 19:46, Bibo Mao wrote:
>> When cpu is hotplug out, cpu is in idle state and function
> "When a CPU is hot-unplugged, it is put into idle state and the function
> ... is called"
Will do in next patch.
>> arch_cpu_idle_dead is called. Timer interrupt for this processor should
>> be disabled, else there will be timer interrupt for the dead cpu. Also
>> this prevents vcpu to schedule out during halt-polling flow when system
>> is running in vm mode, since there is pending timer interrupt.
>
> The logical relationship is a bit unclear, is my paraphrasing correct in
> your opinion?
>
> "Timer interrupt for this processor should be disabled, else a pending
> timer interrupt will prevent the vCPU from scheduling out during the
> halt-polling flow when system is running in VM mode"
>
> (I don't immediately know what a "schedule out" is. Is that a
> translation artifact or some KVM jargon?)
how about "prevent the vCPU from giving up scheduling"?
>
>>
>> This patch adds detailed implementation for timer shutdown interface, so
>> that timer will be disabled when cpu is plug-out.
>
> Missing some definite articles too.
>
> "This patch implements the timer shutdown interface so that the timer
> will be properly disabled when a CPU is hot-unplugged"
>
> Is this version better?
sure, will do in next version.
Regards
Bibo Mao
>
>>
>> Signed-off-by: Bibo Mao <[email protected]>
>> ---
>> arch/loongarch/kernel/time.c | 9 ++-------
>> 1 file changed, 2 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
>> index 3064af94db9c..2920770e30a9 100644
>> --- a/arch/loongarch/kernel/time.c
>> +++ b/arch/loongarch/kernel/time.c
>> @@ -58,7 +58,7 @@ static int constant_set_state_oneshot(struct
>> clock_event_device *evt)
>> return 0;
>> }
>> -static int constant_set_state_oneshot_stopped(struct
>> clock_event_device *evt)
>> +static int constant_set_state_shutdown(struct clock_event_device *evt)
>> {
>> unsigned long timer_config;
>> @@ -90,11 +90,6 @@ static int constant_set_state_periodic(struct
>> clock_event_device *evt)
>> return 0;
>> }
>> -static int constant_set_state_shutdown(struct clock_event_device *evt)
>> -{
>> - return 0;
>> -}
>> -
>> static int constant_timer_next_event(unsigned long delta, struct
>> clock_event_device *evt)
>> {
>> unsigned long timer_config;
>> @@ -161,7 +156,7 @@ int constant_clockevent_init(void)
>> cd->rating = 320;
>> cd->cpumask = cpumask_of(cpu);
>> cd->set_state_oneshot = constant_set_state_oneshot;
>> - cd->set_state_oneshot_stopped = constant_set_state_oneshot_stopped;
>> + cd->set_state_oneshot_stopped = constant_set_state_shutdown;
>> cd->set_state_periodic = constant_set_state_periodic;
>> cd->set_state_shutdown = constant_set_state_shutdown;
>> cd->set_next_event = constant_timer_next_event;
>>
>> base-commit: 9bacdd8996c77c42ca004440be610692275ff9d0
>
> Otherwise LGTM (regarding the renaming of
> constant_set_state_oneshot_stopped, both it and the removed
> constant_set_state_shutdown only has one usage respectively, and looking
> at the function body it's arguably more appropriate to let it take the
> "shutdown" name: it's just clearing the enable bit from the CSR.TCFG and
> nothing else).
>
> With the nits addressed:
>
> Reviewed-by: WANG Xuerui <[email protected]>
>
On 11/16/23 16:21, maobibo wrote:
>>> arch_cpu_idle_dead is called. Timer interrupt for this processor should
>>> be disabled, else there will be timer interrupt for the dead cpu. Also
>>> this prevents vcpu to schedule out during halt-polling flow when system
>>> is running in vm mode, since there is pending timer interrupt.
>>
>> The logical relationship is a bit unclear, is my paraphrasing correct
>> in your opinion?
>>
>> "Timer interrupt for this processor should be disabled, else a
>> pending timer interrupt will prevent the vCPU from scheduling out
>> during the halt-polling flow when system is running in VM mode"
>>
>> (I don't immediately know what a "schedule out" is. Is that a
>> translation artifact or some KVM jargon?)
> how about "prevent the vCPU from giving up scheduling"?
That's very easy to understand, so no problem and thanks!
--
WANG "xen0n" Xuerui
Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/