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

   1 From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   2 Subject: LTTng instrumentation - filemap
   3
   4 Original patch header:
   5   LTTng instrumentation - filemap
   6
   7   Instrumentation of waits caused by memory accesses on mmap regions.
   8
   9   Those tracepoints are used by LTTng.
  10
  11   About the performance impact of tracepoints (which is comparable to markers),
  12   even without immediate values optimizations, tests done by Hideo Aoki on ia64
  13   show no regression. His test case was using hackbench on a kernel where
  14   scheduler instrumentation (about 5 events in code scheduler code) was added.
  15   See the "Tracepoints" patch header for performance result detail.
  16
  17   Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  18   CC: linux-mm@kvack.org
  19   CC: Dave Hansen <haveblue@us.ibm.com>
  20   CC: Masami Hiramatsu <mhiramat@redhat.com>
  21   CC: 'Peter Zijlstra' <peterz@infradead.org>
  22   CC: "Frank Ch. Eigler" <fche@redhat.com>
  23   CC: 'Ingo Molnar' <mingo@elte.hu>
  24   CC: 'Hideo AOKI' <haoki@redhat.com>
  25   CC: Takashi Nishiie <t-nishiie@np.css.fujitsu.com>
  26   CC: 'Steven Rostedt' <rostedt@goodmis.org>
  27   CC: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
  28
  29 Acked-by: Jan Blunck <jblunck@suse.de>
  30 ---
  31  include/trace/filemap.h |   13 +++++++++++++
  32  mm/filemap.c            |    3 +++
  33  2 files changed, 16 insertions(+)
  34
  35 --- /dev/null
  36 +++ b/include/trace/filemap.h
  37 @@ -0,0 +1,13 @@
  38 +#ifndef _TRACE_FILEMAP_H
  39 +#define _TRACE_FILEMAP_H
  40 +
  41 +#include <linux/tracepoint.h>
  42 +
  43 +DEFINE_TRACE(wait_on_page_start,
  44 +       TPPROTO(struct page *page, int bit_nr),
  45 +       TPARGS(page, bit_nr));
  46 +DEFINE_TRACE(wait_on_page_end,
  47 +       TPPROTO(struct page *page, int bit_nr),
  48 +       TPARGS(page, bit_nr));
  49 +
  50 +#endif
  51 --- a/mm/filemap.c
  52 +++ b/mm/filemap.c
  53 @@ -34,6 +34,7 @@
  54  #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
  55  #include <linux/memcontrol.h>
  56  #include "internal.h"
  57 +#include <trace/filemap.h>
  58
  59  /*
  60   * FIXME: remove all knowledge of the buffer layer from the core VM
  61 @@ -540,9 +541,11 @@ void wait_on_page_bit(struct page *page,
  62  {
  63         DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
  64
  65 +       trace_wait_on_page_start(page, bit_nr);
  66         if (test_bit(bit_nr, &page->flags))
  67                 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
  68                                                         TASK_UNINTERRUPTIBLE);
  69 +       trace_wait_on_page_end(page, bit_nr);
  70  }
  71  EXPORT_SYMBOL(wait_on_page_bit);
  72