It is 'perf kmem' support caller statistics for page.  Unlike slab case,
the tracepoints in page allocator don't provide callsite info.  So it
records with callchain and extracts callsite info.

Note that the callchain contains several memory allocation functions
which has no meaning for users.  So skip those functions to get proper
callsites.  I used following regex pattern to skip the allocator
functions:

  ^_?_?(alloc|get_free|get_zeroed)_pages?

This gave me a following list of functions:

  # perf kmem record --page sleep 3
  # perf kmem stat --page -v
  ...
  alloc func: __get_free_pages
  alloc func: get_zeroed_page
  alloc func: alloc_pages_exact
  alloc func: __alloc_pages_direct_compact
  alloc func: __alloc_pages_nodemask
  alloc func: alloc_page_interleave
  alloc func: alloc_pages_current
  alloc func: alloc_pages_vma
  alloc func: alloc_page_buffers
  alloc func: alloc_pages_exact_nid
  ...

The output looks mostly same as --alloc (I also added callsite column
to that) but groups entries by callsite.  Currently, the order,
migrate type and GFP flag info is for the last allocation and not
guaranteed to be same for all allocations from the callsite.

  ---------------------------------------------------------------------------------------------
   Total_alloc (KB) | Hits      | Order | Mig.type | GFP flags | Callsite
  ---------------------------------------------------------------------------------------------
              1,064 |       266 |     0 | UNMOVABL |  000000d0 | __pollwait
                 52 |        13 |     0 | UNMOVABL |  002084d0 | pte_alloc_one
                 44 |        11 |     0 |  MOVABLE |  000280da | handle_mm_fault
                 20 |         5 |     0 |  MOVABLE |  000200da | do_cow_fault
                 20 |         5 |     0 |  MOVABLE |  000200da | do_wp_page
                 16 |         4 |     0 | UNMOVABL |  000084d0 | __pmd_alloc
                 16 |         4 |     0 | UNMOVABL |  00000200 | __tlb_remove_page
                 12 |         3 |     0 | UNMOVABL |  000084d0 | __pud_alloc
                  8 |         2 |     0 | UNMOVABL |  00000010 | bio_copy_user_iov
                  4 |         1 |     0 | UNMOVABL |  000200d2 | pipe_write
                  4 |         1 |     0 |  MOVABLE |  000280da | do_wp_page
                  4 |         1 |     0 | UNMOVABL |  002084d0 | pgd_alloc
  ---------------------------------------------------------------------------------------------
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1429592107-1807-2-git-send-email-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>