lkml.org 
[lkml]   [2006]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 4/6] Have x86_64 use add_active_range() and free_area_init_nodes
On Thu, 31 Aug 2006, Mika Penttilä wrote:

>
>>>> static __init inline int srat_disabled(void)
>>>> @@ -166,7 +167,7 @@ static int hotadd_enough_memory(struct b
>>>>
>>>> if (mem < 0)
>>>> return 0;
>>>> - allowed = (end_pfn - e820_hole_size(0, end_pfn)) * PAGE_SIZE;
>>>> + allowed = (end_pfn - absent_pages_in_range(0, end_pfn)) *
>>>> PAGE_SIZE;
>>>> allowed = (allowed / 100) * hotadd_percent;
>>>> if (allocated + mem > allowed) {
>>>> unsigned long range;
>>>> @@ -238,7 +239,7 @@ static int reserve_hotadd(int node, unsi
>>>> }
>>>>
>>>> /* This check might be a bit too strict, but I'm keeping it for
>>>> now. */
>>>> - if (e820_hole_size(s_pfn, e_pfn) != e_pfn - s_pfn) {
>>>> + if (absent_pages_in_range(s_pfn, e_pfn) != e_pfn - s_pfn) {
>>>> printk(KERN_ERR "SRAT: Hotplug area has existing
>>>> memory\n");
>>>> return -1;
>>>> }
>>>>
>>> We really do want to to compare against the e820 map at it contains
>>> the memory that is really present (this info was blown away before
>>> acpi_numa)
>>
>> The information used by absent_pages_in_range() should match what was
>> available to e820_hole_size().
>>
>>
> But it doesn't : all active ranges are removed before parsing srat. I think
> we really need to check against e820 here.
>

What I see happening is this;

1. setup_arch calls e820_register_active_regions(0, 0, -1UL) so that all
regions are registered as if they were on node 0 so e820_end_of_ram()
gets the right value
2. remove_all_active_regions() is called to clear what was registered so
that rediscovery with NUMA awareness happens
3. acpi_numa_init() is called. It parses the table and a little later
calls acpi_numa_memory_affinity_init() for each range in the table so
now we're into x86_64 code
4. acpi_numa_memory_affinity_init() basically deals an address range.
Assuming the SRAT table is not broken, it calls
e820_register_active_ranges() for that range. At this point, for the
range of addresses, the active ranges are now registered
5. reserve_hotadd is called if the range is hotpluggable. It will fail if
it finds that memory already exists there

So, when absent_pages_in_range() is being called by reserve_hotadd(), it
should be using the same information that was available in e820. What am I
missing?

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
\
 
 \ /
  Last update: 2006-08-31 19:05    [W:0.067 / U:18.836 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site