src/patches/suse-2.6.27.25/patches.trace/lttng-instrumentation-memory.patch

   1 From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   2 Subject: LTTng instrumentation - memory page faults
   3
   4 Original patch header:
   5   LTTng instrumentation - memory page faults
   6
   7   Instrument the page fault entry and exit. Useful to detect delays caused by page
   8   faults and bad memory usage patterns.
   9
  10   Those tracepoints are used by LTTng.
  11
  12   About the performance impact of tracepoints (which is comparable to markers),
  13   even without immediate values optimizations, tests done by Hideo Aoki on ia64
  14   show no regression. His test case was using hackbench on a kernel where
  15   scheduler instrumentation (about 5 events in code scheduler code) was added.
  16   See the "Tracepoints" patch header for performance result detail.
  17
  18   Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  19   CC: Andi Kleen <andi-suse@firstfloor.org>
  20   CC: linux-mm@kvack.org
  21   CC: Dave Hansen <haveblue@us.ibm.com>
  22   CC: Masami Hiramatsu <mhiramat@redhat.com>
  23   CC: 'Peter Zijlstra' <peterz@infradead.org>
  24   CC: "Frank Ch. Eigler" <fche@redhat.com>
  25   CC: 'Ingo Molnar' <mingo@elte.hu>
  26   CC: 'Hideo AOKI' <haoki@redhat.com>
  27   CC: Takashi Nishiie <t-nishiie@np.css.fujitsu.com>
  28   CC: 'Steven Rostedt' <rostedt@goodmis.org>
  29   CC: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
  30
  31 Acked-by: Jan Blunck <jblunck@suse.de>
  32 ---
  33 ---
  34  include/trace/memory.h |   14 ++++++++++++++
  35  mm/memory.c            |   33 ++++++++++++++++++++++++---------
  36  2 files changed, 38 insertions(+), 9 deletions(-)
  37
  38 --- /dev/null
  39 +++ b/include/trace/memory.h
  40 @@ -0,0 +1,14 @@
  41 +#ifndef _TRACE_MEMORY_H
  42 +#define _TRACE_MEMORY_H
  43 +
  44 +#include <linux/tracepoint.h>
  45 +
  46 +DEFINE_TRACE(memory_handle_fault_entry,
  47 +       TPPROTO(struct mm_struct *mm, struct vm_area_struct *vma,
  48 +               unsigned long address, int write_access),
  49 +       TPARGS(mm, vma, address, write_access));
  50 +DEFINE_TRACE(memory_handle_fault_exit,
  51 +       TPPROTO(int res),
  52 +       TPARGS(res));
  53 +
  54 +#endif
  55 --- a/mm/memory.c
  56 +++ b/mm/memory.c
  57 @@ -61,6 +61,7 @@
  58
  59  #include <linux/swapops.h>
  60  #include <linux/elf.h>
  61 +#include <trace/memory.h>
  62
  63  #include "internal.h"
  64
  65 @@ -2832,30 +2833,44 @@ unlock:
  66  int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
  67                 unsigned long address, int write_access)
  68  {
  69 +       int res;
  70         pgd_t *pgd;
  71         pud_t *pud;
  72         pmd_t *pmd;
  73         pte_t *pte;
  74
  75 +       trace_memory_handle_fault_entry(mm, vma, address, write_access);
  76 +
  77         __set_current_state(TASK_RUNNING);
  78
  79         count_vm_event(PGFAULT);
  80
  81 -       if (unlikely(is_vm_hugetlb_page(vma)))
  82 -               return hugetlb_fault(mm, vma, address, write_access);
  83 +       if (unlikely(is_vm_hugetlb_page(vma))) {
  84 +               res = hugetlb_fault(mm, vma, address, write_access);
  85 +               goto end;
  86 +       }
  87
  88         pgd = pgd_offset(mm, address);
  89         pud = pud_alloc(mm, pgd, address);
  90 -       if (!pud)
  91 -               return VM_FAULT_OOM;
  92 +       if (!pud) {
  93 +               res = VM_FAULT_OOM;
  94 +               goto end;
  95 +       }
  96         pmd = pmd_alloc(mm, pud, address);
  97 -       if (!pmd)
  98 -               return VM_FAULT_OOM;
  99 +       if (!pmd) {
 100 +               res = VM_FAULT_OOM;
 101 +               goto end;
 102 +       }
 103         pte = pte_alloc_map(mm, pmd, address);
 104 -       if (!pte)
 105 -               return VM_FAULT_OOM;
 106 +       if (!pte) {
 107 +               res = VM_FAULT_OOM;
 108 +               goto end;
 109 +       }
 110
 111 -       return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
 112 +       res = handle_pte_fault(mm, vma, address, pte, pmd, write_access);
 113 +end:
 114 +       trace_memory_handle_fault_exit(res);
 115 +       return res;
 116  }
 117  EXPORT_SYMBOL_GPL(handle_mm_fault); /* For MoL */
 118