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  1. Jul 09, 2009
    • Tejun Heo's avatar
      linker script: unify usage of discard definition · 023bf6f1
      Tejun Heo authored 
      

Discarded sections in different archs share some commonality but have
considerable differences.  This led to linker script for each arch
implementing its own /DISCARD/ definition, which makes maintaining
tedious and adding new entries error-prone.

This patch makes all linker scripts to move discard definitions to the
end of the linker script and use the common DISCARDS macro.  As ld
uses the first matching section definition, archs can include default
discarded sections by including them earlier in the linker script.

ia64 is notable because it first throws away some ia64 specific
subsections and then include the rest of the sections into the final
image, so those sections must be discarded before the inclusion.

defconfig compile tested for x86, x86-64, powerpc, powerpc64, ia64,
alpha, sparc, sparc64 and s390.  Michal Simek tested microblaze.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarPaul Mundt <lethal@linux-sh.org>
Acked-by: default avatarMike Frysinger <vapier@gentoo.org>
Tested-by: default avatarMichal Simek <monstr@monstr.eu>
Cc: linux-arch@vger.kernel.org
Cc: Michal Simek <monstr@monstr.eu>
Cc: microblaze-uclinux@itee.uq.edu.au
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Tony Luck <tony.luck@intel.com>
      023bf6f1
    • Michal Simek's avatar
      microblaze: include EXIT_TEXT to _stext · 1dcdd091
      Michal Simek authored 
      

Microblaze wants to throw out EXIT_TEXT during runtime too.  This
hasn't caused trouble till now because the linker script didn't
discard EXIT_TEXT and it ended up in its default output section.  As
discard definition is about to be unified, include EXIT_TEXT into
_stext explicitly and while at it replace explicit exitcall definition
to EXIT_CALL.

Signed-off-by: default avatarMichal Simek <monstr@monstr.eu>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      1dcdd091
  3. Jul 04, 2009
    • Tejun Heo's avatar
      percpu: teach large page allocator about NUMA · a530b795
      Tejun Heo authored 
      

Large page first chunk allocator is primarily used for NUMA machines;
however, its NUMA handling is extremely simplistic.  Regardless of
their proximity, each cpu is put into separate large page just to
return most of the allocated space back wasting large amount of
vmalloc space and increasing cache footprint.

This patch teachs NUMA details to large page allocator.  Given
processor proximity information, pcpu_lpage_build_unit_map() will find
fitting cpu -> unit mapping in which cpus in LOCAL_DISTANCE share the
same large page and not too much virtual address space is wasted.

This greatly reduces the unit and thus chunk size and wastes much less
address space for the first chunk.  For example, on 4/4 NUMA machine,
the original code occupied 16MB of virtual space for the first chunk
while the new code only uses 4MB - one 2MB page for each node.

[ Impact: much better space efficiency on NUMA machines ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Miller <davem@davemloft.net>
      a530b795
    • Tejun Heo's avatar
      percpu: allow non-linear / sparse cpu -> unit mapping · 2f39e637
      Tejun Heo authored 
      

Currently cpu and unit are always identity mapped.  To allow more
efficient large page support on NUMA and lazy allocation for possible
but offline cpus, cpu -> unit mapping needs to be non-linear and/or
sparse.  This can be easily implemented by adding a cpu -> unit
mapping array and using it whenever looking up the matching unit for a
cpu.

The only unusal conversion is in pcpu_chunk_addr_search().  The passed
in address is unit0 based and unit0 might not be in use so it needs to
be converted to address of an in-use unit.  This is easily done by
adding the unit offset for the current processor.

[ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
      2f39e637
    • Tejun Heo's avatar
      percpu: drop pcpu_chunk->page[] · ce3141a2
      Tejun Heo authored 
      

percpu core doesn't need to tack all the allocated pages.  It needs to
know whether certain pages are populated and a way to reverse map
address to page when freeing.  This patch drops pcpu_chunk->page[] and
use populated bitmap and vmalloc_to_page() lookup instead.  Using
vmalloc_to_page() exclusively is also possible but complicates first
chunk handling, inflates cache footprint and prevents non-standard
memory allocation for percpu memory.

pcpu_chunk->page[] was used to track each page's allocation and
allowed asymmetric population which happens during failure path;
however, with single bitmap for all units, this is no longer possible.
Bite the bullet and rewrite (de)populate functions so that things are
done in clearly separated steps such that asymmetric population
doesn't happen.  This makes the (de)population process much more
modular and will also ease implementing non-standard memory usage in
the future (e.g. large pages).

This makes @get_page_fn parameter to pcpu_setup_first_chunk()
unnecessary.  The parameter is dropped and all first chunk helpers are
updated accordingly.  Please note that despite the volume most changes
to first chunk helpers are symbol renames for variables which don't
need to be referenced outside of the helper anymore.

This change reduces memory usage and cache footprint of pcpu_chunk.
Now only #unit_pages bits are necessary per chunk.

[ Impact: reduced memory usage and cache footprint for bookkeeping ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
      ce3141a2
    • Tejun Heo's avatar
      percpu: reorder a few functions in mm/percpu.c · c8a51be4
      Tejun Heo authored 
      

(de)populate functions are about to be reimplemented to drop
pcpu_chunk->page array.  Move a few functions so that the rewrite
patch doesn't have code movement making it more difficult to read.

[ Impact: code movement ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
      c8a51be4
    • Tejun Heo's avatar
      percpu: simplify pcpu_setup_first_chunk() · 38a6be52
      Tejun Heo authored 
      

Now that all first chunk allocator helpers allocate and map the first
chunk themselves, there's no need to have optional default alloc/map
in pcpu_setup_first_chunk().  Drop @populate_pte_fn and only leave
@dyn_size optional and make all other params mandatory.

This makes it much easier to follow what pcpu_setup_first_chunk() is
doing and what actual differences tweaking each parameter results in.

[ Impact: drop unused code path ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
      38a6be52
    • Tejun Heo's avatar
      x86,percpu: generalize lpage first chunk allocator · 8c4bfc6e
      Tejun Heo authored 
      

Generalize and move x86 setup_pcpu_lpage() into
pcpu_lpage_first_chunk().  setup_pcpu_lpage() now is a simple wrapper
around the generalized version.  Other than taking size parameters and
using arch supplied callbacks to allocate/free/map memory,
pcpu_lpage_first_chunk() is identical to the original implementation.

This simplifies arch code and will help converting more archs to
dynamic percpu allocator.

While at it, factor out pcpu_calc_fc_sizes() which is common to
pcpu_embed_first_chunk() and pcpu_lpage_first_chunk().

[ Impact: code reorganization and generalization ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
      8c4bfc6e
    • Tejun Heo's avatar
      percpu: make 4k first chunk allocator map memory · 8f05a6a6
      Tejun Heo authored 
      

At first, percpu first chunk was always setup page-by-page by the
generic code.  To add other allocators, different parts of the generic
initialization was made optional.  Now we have three allocators -
embed, remap and 4k.  embed and remap fully handle allocation and
mapping of the first chunk while 4k still depends on generic code for
those.  This makes the generic alloc/map paths specifci to 4k and
makes the code unnecessary complicated with optional generic
behaviors.

This patch makes the 4k allocator to allocate and map memory directly
instead of depending on the generic code.  The only outside visible
change is that now dynamic area in the first chunk is allocated
up-front instead of on-demand.  This doesn't make any meaningful
difference as the area is minimal (usually less than a page, just
enough to fill the alignment) on 4k allocator.  Plus, dynamic area in
the first chunk usually gets fully used anyway.

This will allow simplification of pcpu_setpu_first_chunk() and removal
of chunk->page array.

[ Impact: no outside visible change other than up-front allocation of dyn area ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
      8f05a6a6
    • Tejun Heo's avatar
      x86,percpu: generalize 4k first chunk allocator · d4b95f80
      Tejun Heo authored 
      

Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk().
setup_pcpu_4k() now is a simple wrapper around the generalized
version.  Other than taking size parameters and using arch supplied
callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical
to the original implementation.

This simplifies arch code and will help converting more archs to
dynamic percpu allocator.

While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for
consistency.

[ Impact: code reorganization and generalization ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
      d4b95f80
    • Tejun Heo's avatar
      percpu: drop @unit_size from embed first chunk allocator · 788e5abc
      Tejun Heo authored 
      

The only extra feature @unit_size provides is making dead space at the
end of the first chunk which doesn't have any valid usecase.  Drop the
parameter.  This will increase consistency with generalized 4k
allocator.

James Bottomley spotted missing conversion for the default
setup_per_cpu_areas() which caused build breakage on all arcsh which
use it.

[ Impact: drop unused code path ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Ingo Molnar <mingo@elte.hu>
      788e5abc
    • Tejun Heo's avatar
      x86: make pcpu_chunk_addr_search() matching stricter · 79ba6ac8
      Tejun Heo authored 
      

The @addr passed into pcpu_chunk_addr_search() is unit0 based address
and thus should be matched inside unit0 area.  Currently, when it uses
chunk size when determining whether the address falls in the first
chunk.  Addresses in unitN where N>0 shouldn't be passed in anyway, so
this doesn't cause any malfunction but fix it for consistency.

[ Impact: mostly cleanup ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
      79ba6ac8
    • Tejun Heo's avatar
      Merge branch 'master' into for-next · c43768cb
      Tejun Heo authored 
      Pull linus#master to merge PER_CPU_DEF_ATTRIBUTES and alpha build fix
changes.  As alpha in percpu tree uses 'weak' attribute instead of
inline assembly, there's no need for __used attribute.

Conflicts:
	arch/alpha/include/asm/percpu.h
	arch/mn10300/kernel/vmlinux.lds.S
	include/linux/percpu-defs.h
      c43768cb
  5. Jul 03, 2009
  7. Jul 02, 2009