Re: [PATCH part1 v6 4/6] x86/mem-hotplug: Support initialize page tables in bottom-up

[Yinghai Lu <yinghai@kernel.org>]

On Wed, Oct 9, 2013 at 12:23 PM, Tejun Heo <tj@kernel.org> wrote:
> Hello, Yinghai.
>
> On Wed, Oct 09, 2013 at 12:10:34PM -0700, Yinghai Lu wrote:
>> > I still feel quite uneasy about pulling SRAT parsing and ACPI initrd
>> > overriding into early boot.
>>
>> for your reconsidering to parse srat early, I refresh that old patchset
>> at
>>
>> https://git.kernel.org/cgit/linux/kernel/git/yinghai/linux-yinghai.git/log/?h=for-x86-mm-3.13
>>
>> actually looks one-third or haf patches already have your ack.
>
> Yes, but those acks assume that the overall approach is a good idea.
> The biggest issue that I have with the approach is that it is invasive
> and modifies basic structure for an inherently kludgy solution for a
> quite niche problem.  The benefit / cost ratio still seems quite off
> to me - we're making a lot of general changes to serve something very
> specialized, which might not even stay relevant for long time.
>

I really hate adding another the code path.

Now with v7 from Yanfei, will have movable_node boot command parameter and
if that is specified  kernel would allocate ram early in different way.

Parse srat early patchset add about 217 lines, (from x86, ACPI, NUMA,
ia64: split SLIT handling out)

 arch/ia64/kernel/setup.c                |   4 +-
 arch/x86/include/asm/acpi.h             |   3 +-
 arch/x86/include/asm/page_types.h       |   2 +-
 arch/x86/include/asm/pgtable.h          |   2 +-
 arch/x86/include/asm/setup.h            |   9 ++
 arch/x86/kernel/head64.c                |   2 +
 arch/x86/kernel/head_32.S               |   4 +
 arch/x86/kernel/microcode_intel_early.c |   8 +-
 arch/x86/kernel/setup.c                 |  86 ++++++-----
 arch/x86/mm/init.c                      | 101 ++++++++-----
 arch/x86/mm/numa.c                      | 244 +++++++++++++++++++++++++-------
 arch/x86/mm/numa_emulation.c            |   2 +-
 arch/x86/mm/numa_internal.h             |   2 +
 arch/x86/mm/srat.c                      |  11 +-
 drivers/acpi/numa.c                     |  13 +-
 drivers/acpi/osl.c                      | 131 ++++++++++++-----
 include/linux/acpi.h                    |  20 +--
 include/linux/mm.h                      |   3 -
 mm/page_alloc.c                         |  52 +------
 19 files changed, 458 insertions(+), 241 deletions(-)

if I drop last two, aka does not allocate page table on local code.
will only keep page table on first node, will only need to have add 137 lines.

 arch/ia64/kernel/setup.c                |   4 +-
 arch/x86/include/asm/acpi.h             |   3 +-
 arch/x86/include/asm/page_types.h       |   2 +-
 arch/x86/include/asm/setup.h            |   9 ++
 arch/x86/kernel/head64.c                |   2 +
 arch/x86/kernel/head_32.S               |   4 +
 arch/x86/kernel/microcode_intel_early.c |   8 +-
 arch/x86/kernel/setup.c                 |  85 +++++++++------
 arch/x86/mm/init.c                      |  10 +-
 arch/x86/mm/numa.c                      | 188 +++++++++++++++++++++++---------
 arch/x86/mm/numa_emulation.c            |   2 +-
 arch/x86/mm/numa_internal.h             |   2 +
 arch/x86/mm/srat.c                      |  11 +-
 drivers/acpi/numa.c                     |  13 ++-
 drivers/acpi/osl.c                      | 131 +++++++++++++++-------
 include/linux/acpi.h                    |  20 ++--
 include/linux/mm.h                      |   3 -
 mm/page_alloc.c                         |  52 +--------
 18 files changed, 343 insertions(+), 206 deletions(-)

and Yanfei's add about 265 lines

 Documentation/kernel-
parameters.txt |    3 +
 arch/x86/kernel/setup.c             |    9 ++-
 arch/x86/mm/init.c                  |  122 ++++++++++++++++++++++++++++------
 arch/x86/mm/numa.c                  |   11 +++
 include/linux/memblock.h            |   24 +++++++
 include/linux/mm.h                  |    4 +
 mm/Kconfig                          |   17 +++--
 mm/memblock.c                       |  126 +++++++++++++++++++++++++++++++----
 mm/memory_hotplug.c                 |   31 +++++++++
 9 files changed, 306 insertions(+), 41 deletions(-)

For long term to keep the code more maintainable, We really should go
though parse srat table early.

Thanks

Yinghai

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