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 e2a4ff6fc3a6..27fb74b06b3c 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 349d5a93653f..513dc86b5dfa 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 000000000000..d69cbe3c2a4b
--- /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 cc7a4f864036..534505bb39b0 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)