linux-kernel - Re: [PATCH v2 4/5] page_alloc: Make movablecore

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Date:	Thu, 6 Dec 2012 10:26:33 +0800
From:	Jiang Liu <jiang.liu@...wei.com>
To:	Tang Chen <tangchen@...fujitsu.com>
CC:	Jiang Liu <liuj97@...il.com>, <hpa@...or.com>,
	<akpm@...ux-foundation.org>, <rob@...dley.net>,
	<isimatu.yasuaki@...fujitsu.com>, <laijs@...fujitsu.com>,
	<wency@...fujitsu.com>, <linfeng@...fujitsu.com>,
	<yinghai@...nel.org>, <kosaki.motohiro@...fujitsu.com>,
	<minchan.kim@...il.com>, <mgorman@...e.de>, <rientjes@...gle.com>,
	<rusty@...tcorp.com.au>, <linux-kernel@...r.kernel.org>,
	<linux-mm@...ck.org>, <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v2 4/5] page_alloc: Make movablecore_map has higher priority

On 2012-12-6 9:26, Tang Chen wrote:
> On 12/05/2012 11:43 PM, Jiang Liu wrote:
>> If we make "movablecore_map" take precedence over "movablecore/kernelcore",
>> the logic could be simplified. I think it's not so attractive to support
>> both "movablecore_map" and "movablecore/kernelcore" at the same time.
> 
> Hi Liu,
> 
> Thanks for you advice. :)
> 
> Memory hotplug needs different support on different hardware. We are
> trying to figure out a way to satisfy as many users as we can.
> Since it is a little difficult, it may take sometime. :)
> 
> But I still think we need a boot option to support it. Just a metter of
> how to make it easier to use. :)
> 
> Thanks. :)
> 
>>
>> On 11/23/2012 06:44 PM, Tang Chen wrote:
>>> If kernelcore or movablecore is specified at the same time
>>> with movablecore_map, movablecore_map will have higher
>>> priority to be satisfied.
>>> This patch will make find_zone_movable_pfns_for_nodes()
>>> calculate zone_movable_pfn[] with the limit from
>>> zone_movable_limit[].
>>>
>>> Signed-off-by: Tang Chen<tangchen@...fujitsu.com>
>>> Reviewed-by: Wen Congyang<wency@...fujitsu.com>
>>> Reviewed-by: Lai Jiangshan<laijs@...fujitsu.com>
>>> Tested-by: Lin Feng<linfeng@...fujitsu.com>
>>> ---
>>>   mm/page_alloc.c |   35 +++++++++++++++++++++++++++++++----
>>>   1 files changed, 31 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>>> index f23d76a..05bafbb 100644
>>> --- a/mm/page_alloc.c
>>> +++ b/mm/page_alloc.c
>>> @@ -4800,12 +4800,25 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>>>           required_kernelcore = max(required_kernelcore, corepages);
>>>       }
>>>
>>> -    /* If kernelcore was not specified, there is no ZONE_MOVABLE */
>>> -    if (!required_kernelcore)
>>> +    /*
>>> +     * No matter kernelcore/movablecore was limited or not, movable_zone
>>> +     * should always be set to a usable zone index.
>>> +     */
>>> +    find_usable_zone_for_movable();
>>> +
>>> +    /*
>>> +     * If neither kernelcore/movablecore nor movablecore_map is specified,
>>> +     * there is no ZONE_MOVABLE. But if movablecore_map is specified, the
>>> +     * start pfn of ZONE_MOVABLE has been stored in zone_movable_limit[].
>>> +     */
>>> +    if (!required_kernelcore) {
>>> +        if (movablecore_map.nr_map)
>>> +            memcpy(zone_movable_pfn, zone_movable_limit,
>>> +                sizeof(zone_movable_pfn));
>>>           goto out;
>>> +    }
>>>
>>>       /* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
>>> -    find_usable_zone_for_movable();
>>>       usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];
>>>
>>>   restart:
>>> @@ -4833,10 +4846,24 @@ restart:
>>>           for_each_mem_pfn_range(i, nid,&start_pfn,&end_pfn, NULL) {
>>>               unsigned long size_pages;
>>>
>>> +            /*
>>> +             * Find more memory for kernelcore in
>>> +             * [zone_movable_pfn[nid], zone_movable_limit[nid]).
>>> +             */
>>>               start_pfn = max(start_pfn, zone_movable_pfn[nid]);
>>>               if (start_pfn>= end_pfn)
>>>                   continue;
>>>
>>> +            if (zone_movable_limit[nid]) {
>>> +                end_pfn = min(end_pfn, zone_movable_limit[nid]);
>>> +                /* No range left for kernelcore in this node */
>>> +                if (start_pfn>= end_pfn) {
>>> +                    zone_movable_pfn[nid] =
>>> +                            zone_movable_limit[nid];
>>> +                    break;
>>> +                }
>>> +            }
Hi Tang,
	I just to remove the above logic, so the implementation will be greatly
simplified. Please refer to the attachment.
Regards!
Gerry

>>> +
>>>               /* Account for what is only usable for kernelcore */
>>>               if (start_pfn<  usable_startpfn) {
>>>                   unsigned long kernel_pages;
>>> @@ -4896,12 +4923,12 @@ restart:
>>>       if (usable_nodes&&  required_kernelcore>  usable_nodes)
>>>           goto restart;
>>>
>>> +out:
>>>       /* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
>>>       for (nid = 0; nid<  MAX_NUMNODES; nid++)
>>>           zone_movable_pfn[nid] =
>>>               roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);
>>>
>>> -out:
>>>       /* restore the node_state */
>>>       node_states[N_HIGH_MEMORY] = saved_node_state;
>>>   }
>>>
>>
>>
> 
> 
> .
> 


View attachment "0003-page_alloc-Introduce-zone_movable_limit-to-keep-mova.patch" of type "text/x-patch" (4380 bytes)