Merge branch 'for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu

Pull percpu updates from Tejun Heo:
 "A lot of changes for percpu this time around. percpu inherited the
  same area allocator from the original pre-virtual-address-mapped
  implementation. This was from the time when percpu allocator wasn't
  used all that much and the implementation was focused on simplicity,
  with the unfortunate computational complexity of O(number of areas
  allocated from the chunk) per alloc / free.

  With the increase in percpu usage, we're hitting cases where the lack
  of scalability is hurting. The most prominent one right now is bpf
  perpcu map creation / destruction which may allocate and free a lot of
  entries consecutively and it's likely that the problem will become
  more prominent in the future.

  To address the issue, Dennis replaced the area allocator with hinted
  bitmap allocator which is more consistent. While the new allocator
  does perform a bit worse in some cases, it outperforms the old
  allocator way more than an order of magnitude in other more common
  scenarios while staying mostly flat in CPU overhead and completely
  flat in memory consumption"

* 'for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (27 commits)
  percpu: update header to contain bitmap allocator explanation.
  percpu: update pcpu_find_block_fit to use an iterator
  percpu: use metadata blocks to update the chunk contig hint
  percpu: update free path to take advantage of contig hints
  percpu: update alloc path to only scan if contig hints are broken
  percpu: keep track of the best offset for contig hints
  percpu: skip chunks if the alloc does not fit in the contig hint
  percpu: add first_bit to keep track of the first free in the bitmap
  percpu: introduce bitmap metadata blocks
  percpu: replace area map allocator with bitmap
  percpu: generalize bitmap (un)populated iterators
  percpu: increase minimum percpu allocation size and align first regions
  percpu: introduce nr_empty_pop_pages to help empty page accounting
  percpu: change the number of pages marked in the first_chunk pop bitmap
  percpu: combine percpu address checks
  percpu: modify base_addr to be region specific
  percpu: setup_first_chunk rename schunk/dchunk to chunk
  percpu: end chunk area maps page aligned for the populated bitmap
  percpu: unify allocation of schunk and dchunk
  percpu: setup_first_chunk remove dyn_size and consolidate logic
  ...

1 files changed, 19 insertions, 1 deletions

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 491b3f5a5f8a..6a5fb939d3e5 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -21,6 +21,25 @@
 /* minimum unit size, also is the maximum supported allocation size */
 #define PCPU_MIN_UNIT_SIZE		PFN_ALIGN(32 << 10)
 
+/* minimum allocation size and shift in bytes */
+#define PCPU_MIN_ALLOC_SHIFT		2
+#define PCPU_MIN_ALLOC_SIZE		(1 << PCPU_MIN_ALLOC_SHIFT)
+
+/* number of bits per page, used to trigger a scan if blocks are > PAGE_SIZE */
+#define PCPU_BITS_PER_PAGE		(PAGE_SIZE >> PCPU_MIN_ALLOC_SHIFT)
+
+/*
+ * This determines the size of each metadata block.  There are several subtle
+ * constraints around this constant.  The reserved region must be a multiple of
+ * PCPU_BITMAP_BLOCK_SIZE.  Additionally, PCPU_BITMAP_BLOCK_SIZE must be a
+ * multiple of PAGE_SIZE or PAGE_SIZE must be a multiple of
+ * PCPU_BITMAP_BLOCK_SIZE to align with the populated page map. The unit_size
+ * also has to be a multiple of PCPU_BITMAP_BLOCK_SIZE to ensure full blocks.
+ */
+#define PCPU_BITMAP_BLOCK_SIZE		PAGE_SIZE
+#define PCPU_BITMAP_BLOCK_BITS		(PCPU_BITMAP_BLOCK_SIZE >>	\
+					 PCPU_MIN_ALLOC_SHIFT)
+
 /*
  * Percpu allocator can serve percpu allocations before slab is
  * initialized which allows slab to depend on the percpu allocator.
@@ -116,7 +135,6 @@ extern bool is_kernel_percpu_address(unsigned long addr);
 #if !defined(CONFIG_SMP) || !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
 extern void __init setup_per_cpu_areas(void);
 #endif
-extern void __init percpu_init_late(void);
 
 extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp);
 extern void __percpu *__alloc_percpu(size_t size, size_t align);