path: root/Documentation
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authorLi Zefan <lizf@cn.fujitsu.com>2010-05-26 17:22:17 +0800
committerFrederic Weisbecker <fweisbec@gmail.com>2010-06-09 17:31:22 +0200
commit039ca4e74a1cf60bd7487324a564ecf5c981f254 (patch)
tree61c6fa8409961d2e22ef9d04ac54442734ebd41a /Documentation
parent30dbb20e68e6f7df974b77d2350ebad5eb6f6c9e (diff)
tracing: Remove kmemtrace ftrace plugin
We have been resisting new ftrace plugins and removing existing ones, and kmemtrace has been superseded by kmem trace events and perf-kmem, so we remove it. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Acked-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Cc: Ingo Molnar <mingo@elte.hu> Cc: Steven Rostedt <rostedt@goodmis.org> [ remove kmemtrace from the makefile, handle slob too ] Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Diffstat (limited to 'Documentation')
2 files changed, 0 insertions, 197 deletions
diff --git a/Documentation/ABI/testing/debugfs-kmemtrace b/Documentation/ABI/testing/debugfs-kmemtrace
deleted file mode 100644
index 5e6a92a02d8..00000000000
--- a/Documentation/ABI/testing/debugfs-kmemtrace
+++ /dev/null
@@ -1,71 +0,0 @@
-What: /sys/kernel/debug/kmemtrace/
-Date: July 2008
-Contact: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
-In kmemtrace-enabled kernels, the following files are created:
- 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
- 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
- Feature size (2 byte)
- Feature ID (1 byte)
- Feature data (Feature size - 3 bytes)
- kmemtrace-user - git://repo.or.cz/kmemtrace-user.git
diff --git a/Documentation/trace/kmemtrace.txt b/Documentation/trace/kmemtrace.txt
deleted file mode 100644
index 6308735e58c..00000000000
--- a/Documentation/trace/kmemtrace.txt
+++ /dev/null
@@ -1,126 +0,0 @@
- kmemtrace - Kernel Memory Tracer
- by Eduard - Gabriel Munteanu
- <eduard.munteanu@linux360.ro>
-I. Introduction
-kmemtrace helps kernel developers figure out two things:
-1) how different allocators (SLAB, SLUB etc.) perform
-2) how kernel code allocates memory and how much
-To do this, we trace every allocation and export information to the userspace
-through the relay interface. We export things such as the number of requested
-bytes, the number of bytes actually allocated (i.e. including internal
-fragmentation), whether this is a slab allocation or a plain kmalloc() and so
-The actual analysis is performed by a userspace tool (see section III for
-details on where to get it from). It logs the data exported by the kernel,
-processes it and (as of writing this) can provide the following information:
-- the total amount of memory allocated and fragmentation per call-site
-- the amount of memory allocated and fragmentation per allocation
-- total memory allocated and fragmentation in the collected dataset
-- number of cross-CPU allocation and frees (makes sense in NUMA environments)
-Moreover, it can potentially find inconsistent and erroneous behavior in
-kernel code, such as using slab free functions on kmalloc'ed memory or
-allocating less memory than requested (but not truly failed allocations).
-kmemtrace also makes provisions for tracing on some arch and analysing the
-data on another.
-II. Design and goals
-kmemtrace was designed to handle rather large amounts of data. Thus, it uses
-the relay interface to export whatever is logged to userspace, which then
-stores it. Analysis and reporting is done asynchronously, that is, after the
-data is collected and stored. By design, it allows one to log and analyse
-on different machines and different arches.
-As of writing this, the ABI is not considered stable, though it might not
-change much. However, no guarantees are made about compatibility yet. When
-deemed stable, the ABI should still allow easy extension while maintaining
-backward compatibility. This is described further in Documentation/ABI.
-Summary of design goals:
- - allow logging and analysis to be done across different machines
- - be fast and anticipate usage in high-load environments (*)
- - be reasonably extensible
- - make it possible for GNU/Linux distributions to have kmemtrace
- included in their repositories
-(*) - one of the reasons Pekka Enberg's original userspace data analysis
- tool's code was rewritten from Perl to C (although this is more than a
- simple conversion)
-III. Quick usage guide
-1) Get a kernel that supports kmemtrace and build it accordingly (i.e. enable
-2) Get the userspace tool and build it:
-$ git clone git://repo.or.cz/kmemtrace-user.git # current repository
-$ cd kmemtrace-user/
-$ ./autogen.sh
-$ ./configure
-$ make
-3) Boot the kmemtrace-enabled kernel if you haven't, preferably in the
-'single' runlevel (so that relay buffers don't fill up easily), and run
-# '$' does not mean user, but root here.
-$ mount -t debugfs none /sys/kernel/debug
-$ mount -t proc none /proc
-$ cd path/to/kmemtrace-user/
-$ ./kmemtraced
-Wait a bit, then stop it with CTRL+C.
-$ cat /sys/kernel/debug/kmemtrace/total_overruns # Check if we didn't
- # overrun, should
- # be zero.
-$ (Optionally) [Run kmemtrace_check separately on each cpu[0-9]*.out file to
- check its correctness]
-$ ./kmemtrace-report
-Now you should have a nice and short summary of how the allocator performs.
-IV. FAQ and known issues
-Q: 'cat /sys/kernel/debug/kmemtrace/total_overruns' is non-zero, how do I fix
-this? Should I worry?
-A: If it's non-zero, this affects kmemtrace's accuracy, depending on how
-large the number is. You can fix it by supplying a higher
-'kmemtrace.subbufs=N' kernel parameter.
-Q: kmemtrace_check reports errors, how do I fix this? Should I worry?
-A: This is a bug and should be reported. It can occur for a variety of
- - possible bugs in relay code
- - possible misuse of relay by kmemtrace
- - timestamps being collected unorderly
-Or you may fix it yourself and send us a patch.
-Q: kmemtrace_report shows many errors, how do I fix this? Should I worry?
-A: This is a known issue and I'm working on it. These might be true errors
-in kernel code, which may have inconsistent behavior (e.g. allocating memory
-with kmem_cache_alloc() and freeing it with kfree()). Pekka Enberg pointed
-out this behavior may work with SLAB, but may fail with other allocators.
-It may also be due to lack of tracing in some unusual allocator functions.
-We don't want bug reports regarding this issue yet.
-V. See also