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authorLinus Torvalds <torvalds@linux-foundation.org>2009-04-05 11:04:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-05 11:04:19 -0700
commit714f83d5d9f7c785f622259dad1f4fad12d64664 (patch)
tree20563541ae438e11d686b4d629074eb002a481b7 /Documentation/ABI
parent8901e7ffc2fa78ede7ce9826dbad68a3a25dc2dc (diff)
parent645dae969c3b8651c5bc7c54a1835ec03820f85f (diff)
downloadlinux-714f83d5d9f7c785f622259dad1f4fad12d64664.tar.bz2
Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (413 commits) tracing, net: fix net tree and tracing tree merge interaction tracing, powerpc: fix powerpc tree and tracing tree interaction ring-buffer: do not remove reader page from list on ring buffer free function-graph: allow unregistering twice trace: make argument 'mem' of trace_seq_putmem() const tracing: add missing 'extern' keywords to trace_output.h tracing: provide trace_seq_reserve() blktrace: print out BLK_TN_MESSAGE properly blktrace: extract duplidate code blktrace: fix memory leak when freeing struct blk_io_trace blktrace: fix blk_probes_ref chaos blktrace: make classic output more classic blktrace: fix off-by-one bug blktrace: fix the original blktrace blktrace: fix a race when creating blk_tree_root in debugfs blktrace: fix timestamp in binary output tracing, Text Edit Lock: cleanup tracing: filter fix for TRACE_EVENT_FORMAT events ftrace: Using FTRACE_WARN_ON() to check "freed record" in ftrace_release() x86: kretprobe-booster interrupt emulation code fix ... Fix up trivial conflicts in arch/parisc/include/asm/ftrace.h include/linux/memory.h kernel/extable.c kernel/module.c
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+What: /sys/kernel/debug/kmemtrace/
+Date: July 2008
+Contact: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
+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
+