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From: "Jan Beulich" <JBeulich@suse.com>
To: Chong Li <lichong659@gmail.com>
Cc: Chong Li <chong.li@wustl.edu>, Sisu Xi <xisisu@gmail.com>,
	George Dunlap <george.dunlap@eu.citrix.com>,
	"dario.faggioli" <dario.faggioli@citrix.com>,
	xen-devel <xen-devel@lists.xen.org>,
	Meng Xu <mengxu@cis.upenn.edu>,
	Dagaen Golomb <dgolomb@seas.upenn.edu>
Subject: Re: [PATCH v8 for Xen 4.7 1/4] xen: enable per-VCPU parameter for RTDS
Date: Mon, 21 Mar 2016 10:25:52 -0600	[thread overview]
Message-ID: <56F02EA002000078000DEF45@prv-mh.provo.novell.com> (raw)
In-Reply-To: <CAGHO-irjtjhZfgNX50wNxUwoO3G+QVhf1LWaL9uaZ2RP-YDM8g@mail.gmail.com>

>>> On 21.03.16 at 17:03, <lichong659@gmail.com> wrote:
> On Mon, Mar 21, 2016 at 10:49 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>> On 21.03.16 at 16:18, <lichong659@gmail.com> wrote:
>>> On Mon, Mar 21, 2016 at 8:35 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>>>> On 18.03.16 at 22:26, <lichong659@gmail.com> wrote:
>>>>> --- a/xen/include/public/domctl.h
>>>>> +++ b/xen/include/public/domctl.h
>>>>> @@ -338,24 +338,64 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_max_vcpus_t);
>>>>>  #define XEN_SCHEDULER_ARINC653 7
>>>>>  #define XEN_SCHEDULER_RTDS     8
>>>>>
>>>>> -/* Set or get info? */
>>>>> +typedef struct xen_domctl_sched_credit {
>>>>> +    uint16_t weight;
>>>>> +    uint16_t cap;
>>>>> +} xen_domctl_sched_credit_t;
>>>>> +
>>>>> +typedef struct xen_domctl_sched_credit2 {
>>>>> +    uint16_t weight;
>>>>> +} xen_domctl_sched_credit2_t;
>>>>> +
>>>>> +typedef struct xen_domctl_sched_rtds {
>>>>> +    uint32_t period;
>>>>> +    uint32_t budget;
>>>>> +} xen_domctl_sched_rtds_t;
>>>>> +
>>>>> +typedef struct xen_domctl_schedparam_vcpu {
>>>>> +    union {
>>>>> +        xen_domctl_sched_credit_t credit;
>>>>> +        xen_domctl_sched_credit2_t credit2;
>>>>> +        xen_domctl_sched_rtds_t rtds;
>>>>> +    } u;
>>>>> +    uint32_t vcpuid;
>>>>> +    uint16_t padding[2];
>>>>
>>>> So why uint16_t[2] instead of just uint32_t? And what's the
>>>> padding needed for in the first place?
>>>
>>> You're right. It's better to use uint32_t, which pads (the struct) to
>>> the 64-bit boundary.
>>
>> Which doesn't answer the "why in the first place" part - I don't
>> see why structure size needs to be a multiple of 64 bits.
>>
> In this patch post,
> 
> http://lists.xen.org/archives/html/xen-devel/2015-07/msg02334.html 
> 
> you had a comment about the structure size, which I think you mean
> the struct size should be a multiple of 64 bits.

Looks like I had got mislead by there being struct
xen_domctl_sched_sedf, but it not being part of the union. I'm
sorry for that.

Jan


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  reply	other threads:[~2016-03-21 16:25 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-18 21:26 [PATCH v8 for Xen 4.7 0/4] Enable per-VCPU parameter for RTDS Chong Li
2016-03-18 21:26 ` [PATCH v8 for Xen 4.7 1/4] xen: enable " Chong Li
2016-03-21 13:35   ` Jan Beulich
2016-03-21 15:18     ` Chong Li
2016-03-21 15:39       ` George Dunlap
2016-03-21 15:49       ` Jan Beulich
2016-03-21 16:03         ` Chong Li
2016-03-21 16:25           ` Jan Beulich [this message]
2016-03-25 18:07             ` Chong Li
2016-03-29 10:58               ` Dario Faggioli
2016-03-29 16:59               ` Dario Faggioli
2016-03-29 17:13                 ` Konrad Rzeszutek Wilk
2016-03-29 17:36                   ` Dario Faggioli
2016-03-18 21:26 ` [PATCH v8 for Xen 4.7 2/4] libxc: " Chong Li
2016-03-29 17:08   ` Dario Faggioli
2016-03-31 16:59   ` Wei Liu
2016-03-18 21:26 ` [PATCH v8 for Xen 4.7 3/4] libxl: " Chong Li
2016-03-30 17:04   ` Dario Faggioli
2016-03-31 16:59   ` Wei Liu
2016-03-18 21:26 ` [PATCH v8 for Xen 4.7 4/4] xl: " Chong Li
2016-03-31 17:00   ` Wei Liu
2016-03-31 17:22     ` Dario Faggioli
2016-03-31 17:17   ` Dario Faggioli
2016-03-31 20:16     ` Wei Liu

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