Re: [PATCH] delte PAGE_ORDER_1G in pod

From: "Zhang, Chunyu" <zhangcy@cn.fujitsu.com>
To: George Dunlap <george.dunlap@citrix.com>,
	"george.dunlap@eu.citrix.com" <george.dunlap@eu.citrix.com>,
	"keir@xen.org" <keir@xen.org>, Jan Beulich <jbeulich@suse.com>,
	"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: [PATCH] delte PAGE_ORDER_1G in pod
Date: Tue, 26 Apr 2016 11:05:27 +0000	[thread overview]
Message-ID: <A43879EB4A7F5F449E2CA8148EA79E51FE7FCF51@G08CNEXMBPEKD01.g08.fujitsu.local> (raw)
In-Reply-To: 571F497F.2070807@citrix.com


>On 26/04/16 11:49, Zhang, Chunyu wrote:
>>
>>> On 26/04/16 08:27, zhangcy wrote:
>>>> PoD does not have cache list for 1GB pages.
>>>>
>>>> Signed-off-by: zhangcy <zhangcy@cn.fujitsu.com>
>>>
>>> Thanks for the patch.  FYI we normally tag the area in the title in a
>>> structured way; I probably would have used something like the following:
>>>
>>> xen/pod: Remove code handling PAGE_ORDER_1G from p2m_pod_cache_add
>> got it, thanks.
>>>
>>> But with regards to the patch itself: The question isn't whether we have
>>> a cache list for 1G pages; the question is whether p2m_pod_cache_add()
>>> will ever be called with order == PAGE_ORDER_1G.
>>>
>>> Taking a quick glance around, it looks like in theory if a guest called
>>> decrease_reservation with order == PAGE_ORDER_1G, you could conceivably
>>> get to p2m_pod_cache_add() with order == PAGE_ORDER_1G.
>> i just think like this:
>>
>> p2m_pod_decrease_reservation
>>   - if ( steal_for_cache && p2m_is_ram(t) )
>>      - p2m_pod_cache_add(p2m, page, cur_order)
>> i think p2m_is_ram(t) , ram also from pod cache,
>
>No, that's memory from the guest's p2m table.  The p2m table can have 1G
right..
sorry , i did not write clearly.
i mean: ram come like this:
- pod cache is 4K or 2M
- ram get from pod cache
- set ram to p2m table.
so i think p2m table is 4K or 2M.

i not sure about this O(∩_∩)O~
>entries.
>
> -George
>
>
>

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel