Skip to content

Commit

Permalink
Merge branch 'tracing/core-v2' into tracing-for-linus
Browse files Browse the repository at this point in the history
Conflicts:
	include/linux/slub_def.h
	lib/Kconfig.debug
	mm/slob.c
	mm/slub.c
  • Loading branch information
Ingo Molnar committed Apr 1, 2009
2 parents 4fe7041 + 2e57289 commit 8302294
Show file tree
Hide file tree
Showing 149 changed files with 14,718 additions and 3,785 deletions.
71 changes: 71 additions & 0 deletions Documentation/ABI/testing/debugfs-kmemtrace
Original file line number Diff line number Diff line change
@@ -0,0 +1,71 @@
What: /sys/kernel/debug/kmemtrace/
Date: July 2008
Contact: Eduard - Gabriel Munteanu <[email protected]>
Description:

In kmemtrace-enabled kernels, the following files are created:

/sys/kernel/debug/kmemtrace/
cpu<n> (0400) Per-CPU tracing data, see below. (binary)
total_overruns (0400) Total number of bytes which were dropped from
cpu<n> files because of full buffer condition,
non-binary. (text)
abi_version (0400) Kernel's kmemtrace ABI version. (text)

Each per-CPU file should be read according to the relay interface. That is,
the reader should set affinity to that specific CPU and, as currently done by
the userspace application (though there are other methods), use poll() with
an infinite timeout before every read(). Otherwise, erroneous data may be
read. The binary data has the following _core_ format:

Event ID (1 byte) Unsigned integer, one of:
0 - represents an allocation (KMEMTRACE_EVENT_ALLOC)
1 - represents a freeing of previously allocated memory
(KMEMTRACE_EVENT_FREE)
Type ID (1 byte) Unsigned integer, one of:
0 - this is a kmalloc() / kfree()
1 - this is a kmem_cache_alloc() / kmem_cache_free()
2 - this is a __get_free_pages() et al.
Event size (2 bytes) Unsigned integer representing the
size of this event. Used to extend
kmemtrace. Discard the bytes you
don't know about.
Sequence number (4 bytes) Signed integer used to reorder data
logged on SMP machines. Wraparound
must be taken into account, although
it is unlikely.
Caller address (8 bytes) Return address to the caller.
Pointer to mem (8 bytes) Pointer to target memory area. Can be
NULL, but not all such calls might be
recorded.

In case of KMEMTRACE_EVENT_ALLOC events, the next fields follow:

Requested bytes (8 bytes) Total number of requested bytes,
unsigned, must not be zero.
Allocated bytes (8 bytes) Total number of actually allocated
bytes, unsigned, must not be lower
than requested bytes.
Requested flags (4 bytes) GFP flags supplied by the caller.
Target CPU (4 bytes) Signed integer, valid for event id 1.
If equal to -1, target CPU is the same
as origin CPU, but the reverse might
not be true.

The data is made available in the same endianness the machine has.

Other event ids and type ids may be defined and added. Other fields may be
added by increasing event size, but see below for details.
Every modification to the ABI, including new id definitions, are followed
by bumping the ABI version by one.

Adding new data to the packet (features) is done at the end of the mandatory
data:
Feature size (2 byte)
Feature ID (1 byte)
Feature data (Feature size - 3 bytes)


Users:
kmemtrace-user - git://repo.or.cz/kmemtrace-user.git

Loading

0 comments on commit 8302294

Please sign in to comment.