Hello guys,
Could anyone help reviewing this part?
The first part has been merged into linus's tree. And I've tried to apply this part
to today's linus tree:
commit 42a2d923cc349583ebf6fdd52a7d35e1c2f7e6bd
Merge: 5cbb3d2 75ecab1
Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Wed Nov 13 17:40:34 2013 +0900
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
No conflict, no compiling error and it works well.
Tejun, any comments?
On 10/12/2013 02:00 PM, Zhang Yanfei wrote:
> Hello guys, this is the part2 of our memory hotplug work. This part
> is based on the part1:
> "x86, memblock: Allocate memory near kernel image before SRAT parsed"
> which is base on 3.12-rc4.
>
> You could refer part1 from: https://lkml.org/lkml/2013/10/10/644
>
> Any comments are welcome! Thanks!
>
> [Problem]
>
> The current Linux cannot migrate pages used by the kerenl because
> of the kernel direct mapping. In Linux kernel space, va = pa + PAGE_OFFSET.
> When the pa is changed, we cannot simply update the pagetable and
> keep the va unmodified. So the kernel pages are not migratable.
>
> There are also some other issues will cause the kernel pages not migratable.
> For example, the physical address may be cached somewhere and will be used.
> It is not to update all the caches.
>
> When doing memory hotplug in Linux, we first migrate all the pages in one
> memory device somewhere else, and then remove the device. But if pages are
> used by the kernel, they are not migratable. As a result, memory used by
> the kernel cannot be hot-removed.
>
> Modifying the kernel direct mapping mechanism is too difficult to do. And
> it may cause the kernel performance down and unstable. So we use the following
> way to do memory hotplug.
>
>
> [What we are doing]
>
> In Linux, memory in one numa node is divided into several zones. One of the
> zones is ZONE_MOVABLE, which the kernel won't use.
>
> In order to implement memory hotplug in Linux, we are going to arrange all
> hotpluggable memory in ZONE_MOVABLE so that the kernel won't use these memory.
>
> To do this, we need ACPI's help.
>
>
> [How we do this]
>
> In ACPI, SRAT(System Resource Affinity Table) contains NUMA info. The memory
> affinities in SRAT record every memory range in the system, and also, flags
> specifying if the memory range is hotpluggable.
> (Please refer to ACPI spec 5.0 5.2.16)
>
> With the help of SRAT, we have to do the following two things to achieve our
> goal:
>
> 1. When doing memory hot-add, allow the users arranging hotpluggable as
> ZONE_MOVABLE.
> (This has been done by the MOVABLE_NODE functionality in Linux.)
>
> 2. when the system is booting, prevent bootmem allocator from allocating
> hotpluggable memory for the kernel before the memory initialization
> finishes.
> (This is what we are going to do. See below.)
>
>
> [About this patch-set]
>
> In previous part's patches, we have made the kernel allocate memory near
> kernel image before SRAT parsed to avoid allocating hotpluggable memory
> for kernel. So this patch-set does the following things:
>
> 1. Improve memblock to support flags, which are used to indicate different
> memory type.
>
> 2. Mark all hotpluggable memory in memblock.memory[].
>
> 3. Make the default memblock allocator skip hotpluggable memory.
>
> 4. Improve "movable_node" boot option to have higher priority of movablecore
> and kernelcore boot option.
>
> Change log v1 -> v2:
> 1. Rebase this part on the v7 version of part1
> 2. Fix bug: If movable_node boot option not specified, memblock still
> checks hotpluggable memory when allocating memory.
>
> Tang Chen (7):
> memblock, numa: Introduce flag into memblock
> memblock, mem_hotplug: Introduce MEMBLOCK_HOTPLUG flag to mark
> hotpluggable regions
> memblock: Make memblock_set_node() support different memblock_type
> acpi, numa, mem_hotplug: Mark hotpluggable memory in memblock
> acpi, numa, mem_hotplug: Mark all nodes the kernel resides
> un-hotpluggable
> memblock, mem_hotplug: Make memblock skip hotpluggable regions if
> needed
> x86, numa, acpi, memory-hotplug: Make movable_node have higher
> priority
>
> Yasuaki Ishimatsu (1):
> x86: get pg_data_t's memory from other node
>
> arch/metag/mm/init.c | 3 +-
> arch/metag/mm/numa.c | 3 +-
> arch/microblaze/mm/init.c | 3 +-
> arch/powerpc/mm/mem.c | 2 +-
> arch/powerpc/mm/numa.c | 8 ++-
> arch/sh/kernel/setup.c | 4 +-
> arch/sparc/mm/init_64.c | 5 +-
> arch/x86/mm/init_32.c | 2 +-
> arch/x86/mm/init_64.c | 2 +-
> arch/x86/mm/numa.c | 63 +++++++++++++++++++++--
> arch/x86/mm/srat.c | 5 ++
> include/linux/memblock.h | 39 ++++++++++++++-
> mm/memblock.c | 123 ++++++++++++++++++++++++++++++++++++++-------
> mm/memory_hotplug.c | 1 +
> mm/page_alloc.c | 28 ++++++++++-
> 15 files changed, 252 insertions(+), 39 deletions(-)
>
--
Thanks.
Zhang Yanfei
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