tracing/kmemtrace: normalize the raw tracer event to the unified tracing API

Impact: new tracer plugin

This patch adapts kmemtrace raw events tracing to the unified tracing API.

To enable and use this tracer, just do the following:

 echo kmemtrace > /debugfs/tracing/current_tracer
 cat /debugfs/tracing/trace

You will have the following output:

 # tracer: kmemtrace
 #
 #
 # ALLOC  TYPE  REQ   GIVEN  FLAGS           POINTER         NODE    CALLER
 # FREE   |      |     |       |              |   |            |        |
 # |

type_id 1 call_site 18446744071565527833 ptr 18446612134395152256
type_id 0 call_site 18446744071565585597 ptr 18446612134405955584 bytes_req 4096 bytes_alloc 4096 gfp_flags 208 node -1
type_id 1 call_site 18446744071565585534 ptr 18446612134405955584
type_id 0 call_site 18446744071565585597 ptr 18446612134405955584 bytes_req 4096 bytes_alloc 4096 gfp_flags 208 node -1
type_id 0 call_site 18446744071565636711 ptr 18446612134345164672 bytes_req 240 bytes_alloc 240 gfp_flags 208 node -1
type_id 1 call_site 18446744071565585534 ptr 18446612134405955584
type_id 0 call_site 18446744071565585597 ptr 18446612134405955584 bytes_req 4096 bytes_alloc 4096 gfp_flags 208 node -1
type_id 0 call_site 18446744071565636711 ptr 18446612134345164912 bytes_req 240 bytes_alloc 240 gfp_flags 208 node -1
type_id 1 call_site 18446744071565585534 ptr 18446612134405955584
type_id 0 call_site 18446744071565585597 ptr 18446612134405955584 bytes_req 4096 bytes_alloc 4096 gfp_flags 208 node -1
type_id 0 call_site 18446744071565636711 ptr 18446612134345165152 bytes_req 240 bytes_alloc 240 gfp_flags 208 node -1
type_id 0 call_site 18446744071566144042 ptr 18446612134346191680 bytes_req 1304 bytes_alloc 1312 gfp_flags 208 node -1
type_id 1 call_site 18446744071565585534 ptr 18446612134405955584
type_id 0 call_site 18446744071565585597 ptr 18446612134405955584 bytes_req 4096 bytes_alloc 4096 gfp_flags 208 node -1
type_id 1 call_site 18446744071565585534 ptr 18446612134405955584

That was to stay backward compatible with the format output produced in
inux/tracepoint.h.

This is the default ouput, but note that I tried something else.

If you change an option:

echo kmem_minimalistic > /debugfs/trace_options

and then cat /debugfs/trace, you will have the following output:

 # tracer: kmemtrace
 #
 #
 # ALLOC  TYPE  REQ   GIVEN  FLAGS           POINTER         NODE    CALLER
 # FREE   |      |     |       |              |   |            |        |
 # |

   -      C                            0xffff88007c088780          file_free_rcu
   +      K   4096   4096   000000d0   0xffff88007cad6000     -1   getname
   -      C                            0xffff88007cad6000          putname
   +      K   4096   4096   000000d0   0xffff88007cad6000     -1   getname
   +      K    240    240   000000d0   0xffff8800790dc780     -1   d_alloc
   -      C                            0xffff88007cad6000          putname
   +      K   4096   4096   000000d0   0xffff88007cad6000     -1   getname
   +      K    240    240   000000d0   0xffff8800790dc870     -1   d_alloc
   -      C                            0xffff88007cad6000          putname
   +      K   4096   4096   000000d0   0xffff88007cad6000     -1   getname
   +      K    240    240   000000d0   0xffff8800790dc960     -1   d_alloc
   +      K   1304   1312   000000d0   0xffff8800791d7340     -1   reiserfs_alloc_inode
   -      C                            0xffff88007cad6000          putname
   +      K   4096   4096   000000d0   0xffff88007cad6000     -1   getname
   -      C                            0xffff88007cad6000          putname
   +      K    992   1000   000000d0   0xffff880079045b58     -1   alloc_inode
   +      K    768   1024   000080d0   0xffff88007c096400     -1   alloc_pipe_info
   +      K    240    240   000000d0   0xffff8800790dca50     -1   d_alloc
   +      K    272    320   000080d0   0xffff88007c088780     -1   get_empty_filp
   +      K    272    320   000080d0   0xffff88007c088000     -1   get_empty_filp

Yeah I shall confess kmem_minimalistic should be: kmem_alternative.

Whatever, I find it more readable but this a personal opinion of course.
We can drop it if you want.

On the ALLOC/FREE column, + means an allocation and - a free.

On the type column, you have K = kmalloc, C = cache, P = page

I would like the flags to be GFP_* strings but that would not be easy to not
break the column with strings....

About the node...it seems to always be -1. I don't know why but that shouldn't
be difficult to find.

I moved linux/tracepoint.h to trace/tracepoint.h as well. I think that would
be more easy to find the tracer headers if they are all in their common
directory.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 391 insertions, 0 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index e2a4ff6fc3a..27fb74b06b3 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -264,6 +264,28 @@ config HW_BRANCH_TRACER
 	  This tracer records all branches on the system in a circular
 	  buffer giving access to the last N branches for each cpu.
 
+config KMEMTRACE
+	bool "Trace SLAB allocations"
+	select TRACING
+	depends on RELAY
+	help
+	  kmemtrace provides tracing for slab allocator functions, such as
+	  kmalloc, kfree, kmem_cache_alloc, kmem_cache_free etc.. Collected
+	  data is then fed to the userspace application in order to analyse
+	  allocation hotspots, internal fragmentation and so on, making it
+	  possible to see how well an allocator performs, as well as debug
+	  and profile kernel code.
+
+	  This requires an userspace application to use. See
+	  Documentation/vm/kmemtrace.txt for more information.
+
+	  Saying Y will make the kernel somewhat larger and slower. However,
+	  if you disable kmemtrace at run-time or boot-time, the performance
+	  impact is minimal (depending on the arch the kernel is built for).
+
+	  If unsure, say N.
+
+
 config DYNAMIC_FTRACE
 	bool "enable/disable ftrace tracepoints dynamically"
 	depends on FUNCTION_TRACER
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 349d5a93653..513dc86b5df 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -33,5 +33,6 @@ obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += trace_functions_graph.o
 obj-$(CONFIG_TRACE_BRANCH_PROFILING) += trace_branch.o
 obj-$(CONFIG_HW_BRANCH_TRACER) += trace_hw_branches.o
 obj-$(CONFIG_POWER_TRACER) += trace_power.o
+obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
 
 libftrace-y := ftrace.o
diff --git a/kernel/trace/kmemtrace.c b/kernel/trace/kmemtrace.c
new file mode 100644
index 00000000000..d69cbe3c2a4
--- /dev/null
+++ b/kernel/trace/kmemtrace.c
@@ -0,0 +1,343 @@
+/*
+ * Memory allocator tracing
+ *
+ * Copyright (C) 2008 Eduard - Gabriel Munteanu
+ * Copyright (C) 2008 Pekka Enberg <penberg@cs.helsinki.fi>
+ * Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
+ */
+
+#include <linux/dcache.h>
+#include <linux/debugfs.h>
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <trace/kmemtrace.h>
+
+#include "trace.h"
+#include "trace_output.h"
+
+/* Select an alternative, minimalistic output than the original one */
+#define TRACE_KMEM_OPT_MINIMAL	0x1
+
+static struct tracer_opt kmem_opts[] = {
+	/* Default disable the minimalistic output */
+	{ TRACER_OPT(kmem_minimalistic, TRACE_KMEM_OPT_MINIMAL) },
+	{ }
+};
+
+static struct tracer_flags kmem_tracer_flags = {
+	.val = 0,
+	.opts = kmem_opts
+};
+
+
+static bool kmem_tracing_enabled __read_mostly;
+static struct trace_array *kmemtrace_array;
+
+static int kmem_trace_init(struct trace_array *tr)
+{
+	int cpu;
+	kmemtrace_array = tr;
+
+	for_each_cpu_mask(cpu, cpu_possible_map)
+		tracing_reset(tr, cpu);
+
+	kmem_tracing_enabled = true;
+
+	return 0;
+}
+
+static void kmem_trace_reset(struct trace_array *tr)
+{
+	kmem_tracing_enabled = false;
+}
+
+static void kmemtrace_headers(struct seq_file *s)
+{
+	/* Don't need headers for the original kmemtrace output */
+	if (!(kmem_tracer_flags.val & TRACE_KMEM_OPT_MINIMAL))
+		return;
+
+	seq_printf(s, "#\n");
+	seq_printf(s, "# ALLOC  TYPE  REQ   GIVEN  FLAGS     "
+			"      POINTER         NODE    CALLER\n");
+	seq_printf(s, "# FREE   |      |     |       |       "
+			"       |   |            |        |\n");
+	seq_printf(s, "# |\n\n");
+}
+
+/*
+ * The two following functions give the original output from kmemtrace,
+ * or something close to....perhaps they need some missing things
+ */
+static enum print_line_t
+kmemtrace_print_alloc_original(struct trace_iterator *iter,
+				struct kmemtrace_alloc_entry *entry)
+{
+	struct trace_seq *s = &iter->seq;
+	int ret;
+
+	/* Taken from the old linux/kmemtrace.h */
+	ret = trace_seq_printf(s, "type_id %d call_site %lu ptr %lu "
+	  "bytes_req %lu bytes_alloc %lu gfp_flags %lu node %d\n",
+	   entry->type_id, entry->call_site, (unsigned long) entry->ptr,
+	   (unsigned long) entry->bytes_req, (unsigned long) entry->bytes_alloc,
+	   (unsigned long) entry->gfp_flags, entry->node);
+
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return TRACE_TYPE_HANDLED;
+}
+
+static enum print_line_t
+kmemtrace_print_free_original(struct trace_iterator *iter,
+				struct kmemtrace_free_entry *entry)
+{
+	struct trace_seq *s = &iter->seq;
+	int ret;
+
+	/* Taken from the old linux/kmemtrace.h */
+	ret = trace_seq_printf(s, "type_id %d call_site %lu ptr %lu\n",
+	   entry->type_id, entry->call_site, (unsigned long) entry->ptr);
+
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return TRACE_TYPE_HANDLED;
+}
+
+
+/* The two other following provide a more minimalistic output */
+static enum print_line_t
+kmemtrace_print_alloc_compress(struct trace_iterator *iter,
+					struct kmemtrace_alloc_entry *entry)
+{
+	struct trace_seq *s = &iter->seq;
+	int ret;
+
+	/* Alloc entry */
+	ret = trace_seq_printf(s, "  +      ");
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Type */
+	switch (entry->type_id) {
+	case KMEMTRACE_TYPE_KMALLOC:
+		ret = trace_seq_printf(s, "K   ");
+		break;
+	case KMEMTRACE_TYPE_CACHE:
+		ret = trace_seq_printf(s, "C   ");
+		break;
+	case KMEMTRACE_TYPE_PAGES:
+		ret = trace_seq_printf(s, "P   ");
+		break;
+	default:
+		ret = trace_seq_printf(s, "?   ");
+	}
+
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Requested */
+	ret = trace_seq_printf(s, "%4d   ", entry->bytes_req);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Allocated */
+	ret = trace_seq_printf(s, "%4d   ", entry->bytes_alloc);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Flags
+	 * TODO: would be better to see the name of the GFP flag names
+	 */
+	ret = trace_seq_printf(s, "%08x   ", entry->gfp_flags);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Pointer to allocated */
+	ret = trace_seq_printf(s, "0x%tx   ", (ptrdiff_t)entry->ptr);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Node */
+	ret = trace_seq_printf(s, "%4d   ", entry->node);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Call site */
+	ret = seq_print_ip_sym(s, entry->call_site, 0);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	if (!trace_seq_printf(s, "\n"))
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return TRACE_TYPE_HANDLED;
+}
+
+static enum print_line_t
+kmemtrace_print_free_compress(struct trace_iterator *iter,
+				struct kmemtrace_free_entry *entry)
+{
+	struct trace_seq *s = &iter->seq;
+	int ret;
+
+	/* Free entry */
+	ret = trace_seq_printf(s, "  -      ");
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Type */
+	switch (entry->type_id) {
+	case KMEMTRACE_TYPE_KMALLOC:
+		ret = trace_seq_printf(s, "K     ");
+		break;
+	case KMEMTRACE_TYPE_CACHE:
+		ret = trace_seq_printf(s, "C     ");
+		break;
+	case KMEMTRACE_TYPE_PAGES:
+		ret = trace_seq_printf(s, "P     ");
+		break;
+	default:
+		ret = trace_seq_printf(s, "?     ");
+	}
+
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Skip requested/allocated/flags */
+	ret = trace_seq_printf(s, "                       ");
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Pointer to allocated */
+	ret = trace_seq_printf(s, "0x%tx   ", (ptrdiff_t)entry->ptr);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Skip node */
+	ret = trace_seq_printf(s, "       ");
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	/* Call site */
+	ret = seq_print_ip_sym(s, entry->call_site, 0);
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	if (!trace_seq_printf(s, "\n"))
+		return TRACE_TYPE_PARTIAL_LINE;
+
+	return TRACE_TYPE_HANDLED;
+}
+
+static enum print_line_t kmemtrace_print_line(struct trace_iterator *iter)
+{
+	struct trace_entry *entry = iter->ent;
+
+	switch (entry->type) {
+	case TRACE_KMEM_ALLOC: {
+		struct kmemtrace_alloc_entry *field;
+		trace_assign_type(field, entry);
+		if (kmem_tracer_flags.val & TRACE_KMEM_OPT_MINIMAL)
+			return kmemtrace_print_alloc_compress(iter, field);
+		else
+			return kmemtrace_print_alloc_original(iter, field);
+	}
+
+	case TRACE_KMEM_FREE: {
+		struct kmemtrace_free_entry *field;
+		trace_assign_type(field, entry);
+		if (kmem_tracer_flags.val & TRACE_KMEM_OPT_MINIMAL)
+			return kmemtrace_print_free_compress(iter, field);
+		else
+			return kmemtrace_print_free_original(iter, field);
+	}
+
+	default:
+		return TRACE_TYPE_UNHANDLED;
+	}
+}
+
+/* Trace allocations */
+void kmemtrace_mark_alloc_node(enum kmemtrace_type_id type_id,
+			     unsigned long call_site,
+			     const void *ptr,
+			     size_t bytes_req,
+			     size_t bytes_alloc,
+			     gfp_t gfp_flags,
+			     int node)
+{
+	struct ring_buffer_event *event;
+	struct kmemtrace_alloc_entry *entry;
+	struct trace_array *tr = kmemtrace_array;
+	unsigned long irq_flags;
+
+	if (!kmem_tracing_enabled)
+		return;
+
+	event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
+					 &irq_flags);
+	if (!event)
+		return;
+	entry	= ring_buffer_event_data(event);
+	tracing_generic_entry_update(&entry->ent, 0, 0);
+
+	entry->ent.type = TRACE_KMEM_ALLOC;
+	entry->call_site = call_site;
+	entry->ptr = ptr;
+	entry->bytes_req = bytes_req;
+	entry->bytes_alloc = bytes_alloc;
+	entry->gfp_flags = gfp_flags;
+	entry->node	=	node;
+
+	ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
+
+	trace_wake_up();
+}
+
+void kmemtrace_mark_free(enum kmemtrace_type_id type_id,
+		       unsigned long call_site,
+		       const void *ptr)
+{
+	struct ring_buffer_event *event;
+	struct kmemtrace_free_entry *entry;
+	struct trace_array *tr = kmemtrace_array;
+	unsigned long irq_flags;
+
+	if (!kmem_tracing_enabled)
+		return;
+
+	event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
+					 &irq_flags);
+	if (!event)
+		return;
+	entry	= ring_buffer_event_data(event);
+	tracing_generic_entry_update(&entry->ent, 0, 0);
+
+	entry->ent.type = TRACE_KMEM_FREE;
+	entry->type_id	= type_id;
+	entry->call_site = call_site;
+	entry->ptr = ptr;
+
+	ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
+
+	trace_wake_up();
+}
+
+static struct tracer kmem_tracer __read_mostly = {
+	.name		= "kmemtrace",
+	.init		= kmem_trace_init,
+	.reset		= kmem_trace_reset,
+	.print_line	= kmemtrace_print_line,
+	.print_header = kmemtrace_headers,
+	.flags		= &kmem_tracer_flags
+};
+
+static int __init init_kmem_tracer(void)
+{
+	return register_tracer(&kmem_tracer);
+}
+
+device_initcall(init_kmem_tracer);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index cc7a4f86403..534505bb39b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -9,6 +9,7 @@
 #include <linux/mmiotrace.h>
 #include <linux/ftrace.h>
 #include <trace/boot.h>
+#include <trace/kmemtrace.h>
 
 enum trace_type {
 	__TRACE_FIRST_TYPE = 0,
@@ -29,6 +30,8 @@ enum trace_type {
 	TRACE_GRAPH_ENT,
 	TRACE_USER_STACK,
 	TRACE_HW_BRANCHES,
+	TRACE_KMEM_ALLOC,
+	TRACE_KMEM_FREE,
 	TRACE_POWER,
 
 	__TRACE_LAST_TYPE
@@ -170,6 +173,24 @@ struct trace_power {
 	struct power_trace	state_data;
 };
 
+struct kmemtrace_alloc_entry {
+	struct trace_entry	ent;
+	enum kmemtrace_type_id type_id;
+	unsigned long call_site;
+	const void *ptr;
+	size_t bytes_req;
+	size_t bytes_alloc;
+	gfp_t gfp_flags;
+	int node;
+};
+
+struct kmemtrace_free_entry {
+	struct trace_entry	ent;
+	enum kmemtrace_type_id type_id;
+	unsigned long call_site;
+	const void *ptr;
+};
+
 /*
  * trace_flag_type is an enumeration that holds different
  * states when a trace occurs. These are:
@@ -280,6 +301,10 @@ extern void __ftrace_bad_type(void);
 			  TRACE_GRAPH_RET);		\
 		IF_ASSIGN(var, ent, struct hw_branch_entry, TRACE_HW_BRANCHES);\
  		IF_ASSIGN(var, ent, struct trace_power, TRACE_POWER); \
+		IF_ASSIGN(var, ent, struct kmemtrace_alloc_entry,	\
+			  TRACE_KMEM_ALLOC);	\
+		IF_ASSIGN(var, ent, struct kmemtrace_free_entry,	\
+			  TRACE_KMEM_FREE);	\
 		__ftrace_bad_type();					\
 	} while (0)