xen: put cpupool's member 'n_dom' after 'cpupool_id'

[Xen-devel] [PATCH] xen: put cpupool's member 'n_dom' after 'cpupool_id'

Posted by Baodong Chen 4 years, 10 months ago

Thus, sizeof(struct cpupool) will save 8 bytes for 64-bit system.

Signed-off-by: Baodong Chen <chenbaodong@mxnavi.com>
---
 xen/include/xen/sched-if.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
index 92bc7a0..f0cf210 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -213,9 +213,9 @@ static inline void sched_free_domdata(const struct scheduler *s,
 struct cpupool
 {
     int              cpupool_id;
+    unsigned int     n_dom;
     cpumask_var_t    cpu_valid;      /* all cpus assigned to pool */
     struct cpupool   *next;
-    unsigned int     n_dom;
     struct scheduler *sched;
     atomic_t         refcnt;
 };
-- 
2.7.4


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Re: [Xen-devel] [PATCH] xen: put cpupool's member 'n_dom' after 'cpupool_id'

Posted by Julien Grall 4 years, 10 months ago

Hi,

On 5/31/19 4:18 AM, Baodong Chen wrote:
> Thus, sizeof(struct cpupool) will save 8 bytes for 64-bit system.

I am happy with the change, although AFAIK cpupool is not instantiated 
that often. Are you planning to have more instantiation of it?

Cheers,

> 
> Signed-off-by: Baodong Chen <chenbaodong@mxnavi.com>
> ---
>   xen/include/xen/sched-if.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
> index 92bc7a0..f0cf210 100644
> --- a/xen/include/xen/sched-if.h
> +++ b/xen/include/xen/sched-if.h
> @@ -213,9 +213,9 @@ static inline void sched_free_domdata(const struct scheduler *s,
>   struct cpupool
>   {
>       int              cpupool_id;
> +    unsigned int     n_dom;
>       cpumask_var_t    cpu_valid;      /* all cpus assigned to pool */
>       struct cpupool   *next;
> -    unsigned int     n_dom;
>       struct scheduler *sched;
>       atomic_t         refcnt;
>   };
> 

-- 
Julien Grall

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Re: [Xen-devel] [PATCH] xen: put cpupool's member 'n_dom' after 'cpupool_id'

Posted by chenbaodong 4 years, 10 months ago

On 5/31/19 18:52, Julien Grall wrote:
> Hi,
>
> On 5/31/19 4:18 AM, Baodong Chen wrote:
>> Thus, sizeof(struct cpupool) will save 8 bytes for 64-bit system.
>
> I am happy with the change, although AFAIK cpupool is not instantiated 
> that often. Are you planning to have more instantiation of it?
>
> Cheers,
>
No, I'm not planning to create lots of cpupool instance.

I'm studying xen for a few weeks and my plan is:

run xen for embeded automotive use case with dom0less, null scheduler, 
small code base for safety certified maybe a plus(not sure whether can 
do this).


>>
>> Signed-off-by: Baodong Chen <chenbaodong@mxnavi.com>
>> ---
>>   xen/include/xen/sched-if.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
>> index 92bc7a0..f0cf210 100644
>> --- a/xen/include/xen/sched-if.h
>> +++ b/xen/include/xen/sched-if.h
>> @@ -213,9 +213,9 @@ static inline void sched_free_domdata(const 
>> struct scheduler *s,
>>   struct cpupool
>>   {
>>       int              cpupool_id;
>> +    unsigned int     n_dom;
>>       cpumask_var_t    cpu_valid;      /* all cpus assigned to pool */
>>       struct cpupool   *next;
>> -    unsigned int     n_dom;
>>       struct scheduler *sched;
>>       atomic_t         refcnt;
>>   };
>>
>

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Re: [Xen-devel] [PATCH] xen: put cpupool's member 'n_dom' after 'cpupool_id'

Posted by Julien Grall 4 years, 10 months ago

Hi,

On 03/06/2019 02:48, chenbaodong wrote:
> 
> On 5/31/19 18:52, Julien Grall wrote:
>> Hi,
>>
>> On 5/31/19 4:18 AM, Baodong Chen wrote:
>>> Thus, sizeof(struct cpupool) will save 8 bytes for 64-bit system.
>>
>> I am happy with the change, although AFAIK cpupool is not instantiated that 
>> often. Are you planning to have more instantiation of it?
>>
>> Cheers,
>>
> No, I'm not planning to create lots of cpupool instance.
> 
> I'm studying xen for a few weeks and my plan is:
> 
> run xen for embeded automotive use case with dom0less, null scheduler, small 
> code base for safety certified maybe a plus(not sure whether can do this).

FWIW, there are discussion to get Xen safety certified. They are captured on [1].

Cheers,

[1] https://wiki.xenproject.org/wiki/Category:Safety_Certification/FuSa_SIG

> 
> 
>>>
>>> Signed-off-by: Baodong Chen <chenbaodong@mxnavi.com>
>>> ---
>>>   xen/include/xen/sched-if.h | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
>>> index 92bc7a0..f0cf210 100644
>>> --- a/xen/include/xen/sched-if.h
>>> +++ b/xen/include/xen/sched-if.h
>>> @@ -213,9 +213,9 @@ static inline void sched_free_domdata(const struct 
>>> scheduler *s,
>>>   struct cpupool
>>>   {
>>>       int              cpupool_id;
>>> +    unsigned int     n_dom;
>>>       cpumask_var_t    cpu_valid;      /* all cpus assigned to pool */
>>>       struct cpupool   *next;
>>> -    unsigned int     n_dom;
>>>       struct scheduler *sched;
>>>       atomic_t         refcnt;
>>>   };
>>>
>>

-- 
Julien Grall

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Re: [Xen-devel] [PATCH] xen: put cpupool's member 'n_dom' after 'cpupool_id'

Posted by chenbaodong 4 years, 10 months ago

On 6/3/19 17:30, Julien Grall wrote:
> Hi,
>
> On 03/06/2019 02:48, chenbaodong wrote:
>>
>> On 5/31/19 18:52, Julien Grall wrote:
>>> Hi,
>>>
>>> On 5/31/19 4:18 AM, Baodong Chen wrote:
>>>> Thus, sizeof(struct cpupool) will save 8 bytes for 64-bit system.
>>>
>>> I am happy with the change, although AFAIK cpupool is not 
>>> instantiated that often. Are you planning to have more instantiation 
>>> of it?
>>>
>>> Cheers,
>>>
>> No, I'm not planning to create lots of cpupool instance.
>>
>> I'm studying xen for a few weeks and my plan is:
>>
>> run xen for embeded automotive use case with dom0less, null 
>> scheduler, small code base for safety certified maybe a plus(not sure 
>> whether can do this).
>
> FWIW, there are discussion to get Xen safety certified. They are 
> captured on [1].
>
> Cheers,
>
> [1] 
> https://wiki.xenproject.org/wiki/Category:Safety_Certification/FuSa_SIG

Hello Julien, Thanks for your info.

I will follow the wiki link and see what i can do about safety 
certification.

>
>>
>>
>>>>
>>>> Signed-off-by: Baodong Chen <chenbaodong@mxnavi.com>
>>>> ---
>>>>   xen/include/xen/sched-if.h | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
>>>> index 92bc7a0..f0cf210 100644
>>>> --- a/xen/include/xen/sched-if.h
>>>> +++ b/xen/include/xen/sched-if.h
>>>> @@ -213,9 +213,9 @@ static inline void sched_free_domdata(const 
>>>> struct scheduler *s,
>>>>   struct cpupool
>>>>   {
>>>>       int              cpupool_id;
>>>> +    unsigned int     n_dom;
>>>>       cpumask_var_t    cpu_valid;      /* all cpus assigned to pool */
>>>>       struct cpupool   *next;
>>>> -    unsigned int     n_dom;
>>>>       struct scheduler *sched;
>>>>       atomic_t         refcnt;
>>>>   };
>>>>
>>>
>

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Re: [Xen-devel] [PATCH] xen: put cpupool's member 'n_dom' after 'cpupool_id'

Posted by Jan Beulich 4 years, 10 months ago

>>> On 31.05.19 at 05:18, <chenbaodong@mxnavi.com> wrote:
> Thus, sizeof(struct cpupool) will save 8 bytes for 64-bit system.
> 
> Signed-off-by: Baodong Chen <chenbaodong@mxnavi.com>
> ---
>  xen/include/xen/sched-if.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

I've just noticed that this file isn't part of the SCHEDULING
maintainer group. Therefore

Acked-by: Jan Beulich <jbeulich@suse.com>

I'm wondering though whether maintainership of the file shouldn't be
adjusted, preferably by moving this (supposedly private) header into
xen/common/. I realize there may be some further cleanup needed
for this to actually be possible. If there was general consensus about
such a step, I could see about actually carrying it out.

Jan

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Re: [Xen-devel] [PATCH] xen: put cpupool's member 'n_dom' after 'cpupool_id'

Posted by Juergen Gross 4 years, 10 months ago

On 17.06.19 17:19, Jan Beulich wrote:
>>>> On 31.05.19 at 05:18, <chenbaodong@mxnavi.com> wrote:
>> Thus, sizeof(struct cpupool) will save 8 bytes for 64-bit system.
>>
>> Signed-off-by: Baodong Chen <chenbaodong@mxnavi.com>
>> ---
>>   xen/include/xen/sched-if.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> I've just noticed that this file isn't part of the SCHEDULING
> maintainer group. Therefore
> 
> Acked-by: Jan Beulich <jbeulich@suse.com>
> 
> I'm wondering though whether maintainership of the file shouldn't be
> adjusted, preferably by moving this (supposedly private) header into
> xen/common/. I realize there may be some further cleanup needed
> for this to actually be possible. If there was general consensus about
> such a step, I could see about actually carrying it out.

I am planning a big scheduling cleanup series after my core scheduling
series has been processed. sched-if.h is part of that work.


Juergen

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