From: George Dunlap <george.dunlap@citrix.com>
To: Jan Beulich <JBeulich@suse.com>, Olaf Hering <olaf@aepfle.de>
Cc: Tim Deegan <tim@xen.org>,
Stefano Stabellini <sstabellini@kernel.org>,
Wei Liu <wei.liu2@citrix.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
xen-devel@lists.xen.org, Julien Grall <julien.grall@arm.com>
Subject: Re: [PATCH v1] getpageframeinfo3: replace hardcoded batchsize with constant
Date: Fri, 9 Mar 2018 16:49:26 +0000 [thread overview]
Message-ID: <8da306fb-a1e9-e15c-084e-87091cccef83@citrix.com> (raw)
In-Reply-To: <5AA2C7D602000078001B067B@prv-mh.provo.novell.com>
On 03/09/2018 04:43 PM, Jan Beulich wrote:
>>>> On 09.03.18 at 17:30, <george.dunlap@citrix.com> wrote:
>> On 03/09/2018 04:25 PM, Jan Beulich wrote:
>>>>>> On 09.03.18 at 17:17, <olaf@aepfle.de> wrote:
>>>> --- a/xen/include/public/domctl.h
>>>> +++ b/xen/include/public/domctl.h
>>>> @@ -137,6 +137,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_getdomaininfo_t);
>>>> #define XEN_DOMCTL_PFINFO_BROKEN (0xdU<<28) /* broken page */
>>>> #define XEN_DOMCTL_PFINFO_LTAB_MASK (0xfU<<28)
>>>>
>>>> +#define XEN_GETPAGEFRAMEINFO3_MAX_SIZE 1024U
>>>
>>> This is an implementation detail; it shouldn't be made part of the
>>> public interface. If there's a need for user land to know the value,
>>> and if there's currently no way to query it, that's what you
>>> would want to add.
>>
>> But the domctl interface isn't stable, right? There's no need to make a
>> flexible backwards-compatible interface between libxc and Xen; sharing a
>> #define should be fine, as long as there's only one place to change it.
>
> Well, strictly speaking this is an option. But I would prefer if we didn't
> abuse the "is not a stable interface" property, which this changes
> feels like it would.
>
> Furthermore it hasn't become clear to me why, if this hard coded
> number is deemed a problem, we don't get rid of it altogether.
> Domctl-s have long gained the ability to be preemptible - there
> various examples.
Yes, making it preemptible and removing the limit is probably a better
option.
-George
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next prev parent reply other threads:[~2018-03-09 16:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-09 16:17 [PATCH v1] getpageframeinfo3: replace hardcoded batchsize with constant Olaf Hering
2018-03-09 16:25 ` Jan Beulich
2018-03-09 16:30 ` George Dunlap
2018-03-09 16:43 ` Jan Beulich
2018-03-09 16:49 ` George Dunlap [this message]
2018-03-09 16:55 ` Olaf Hering
2018-03-09 17:46 ` George Dunlap
2018-03-09 17:05 ` Andrew Cooper
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