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SubjectRe: [PATCH v3 4/5][RESEND] page_alloc: Make movablecore_map has higher priority
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On Wed, 2012-12-12 at 17:34 +0800, Tang Chen wrote:
> Hi Simon,
>
> Thanks for reviewing. This logic is aimed at make movablecore_map
> coexist with kernelcore/movablecore.
>
> Please see below. :)

Hi Chen,

Thanks for your detail explanation. The logic looks reasonable to me. Bu
t how you guarantee the below changlog in your patchset.
1) If the range is involved in a single node, then from ss to the end of
the node will be ZONE_MOVABLE.
2) If the range covers two or more nodes, then from ss to the end of the
node will be ZONE_MOVABLE, and all the other nodes will only have
ZONE_MOVABLE.

>
> On 12/12/2012 09:33 AM, Simon Jeons wrote:
> >> @@ -4839,9 +4839,17 @@ 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)
> >> + /*
> >> + * 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));
>
> If users didn't specified kernelcore option, then zone_movable_pfn[]
> and zone_movable_limit[] are all the same. We skip the logic.
>
> >> goto out;
> >> + }
> >>
> >> /* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
> >> usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];
> >> @@ -4871,10 +4879,24 @@ 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;
> >>
> >
> > Hi Chen,
> >
> >> + if (zone_movable_limit[nid]) {
>
> If users didn't give any limitation of ZONE_MOVABLE on node i, we could
> skip the logic too.
>
> >> + end_pfn = min(end_pfn, zone_movable_limit[nid]);
>
> In order to reuse the original kernelcore/movablecore logic, we keep
> end_pfn <= zone_movable_limit[nid]. We device [start_pfn, end_pfn) into
> two parts:
> [start_pfn, zone_movable_limit[nid])
> and
> [zone_movable_limit[nid], end_pfn).
>
> We just remove the second part, and go on to the original logic.
>
> >> + /* No range left for kernelcore in this node */
> >> + if (start_pfn>= end_pfn) {
>
> Since we re-evaluated end_pfn, if we have crossed the limitation, we
> should stop.
>
> >> + zone_movable_pfn[nid] =
> >> + zone_movable_limit[nid];
>
> Here, we found the real limitation. That means, the lowest pfn of
> ZONE_MOVABLE is either zone_movable_limit[nid] or the value the original
> logic calculates out, which is below zone_movable_limit[nid].
>
> >> + break;
>
> Then we break and go on to the next node.
>
> >> + }
> >> + }
> >> +
> >
> > Could you explain this part of codes? hard to understand.
> >
> >> /* Account for what is only usable for kernelcore */
> >> if (start_pfn< usable_startpfn) {
> >> unsigned long kernel_pages;
> >> @@ -4934,12 +4956,12 @@ 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;
> >> }
> >
> >
> >
>




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