From a94c80e78bc9f4493ffc25a02d5d7bcd93c399d0 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 12 Nov 2008 17:52:36 -0500 Subject: [PATCH 1/6] ftrace: rename trace_entries to buffer_size_kb Impact: rename of debugfs file trace_entries to buffer_size_kb The original ftrace had fixed size entries, and the number of entries was shown and modified via the file called trace_entries. By converting to the unified trace buffer, we now allow for variable size entries which makes the meaning of trace_entries pointless. Since trace_size might be confused to the size of the trace, this patch names it "buffer_size_kb" (thanks to Arjan van de Ven for this idea). [ mingo@elte.hu: changed from buffer_size to buffer_size_kb ] ( Note, the units are still bytes - the next patch changes that, to keep the wide rename patch separate from the unit-change patch. ) Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- Documentation/ftrace.txt | 18 +++++++++--------- kernel/trace/trace.c | 4 ++-- 2 files changed, 11 insertions(+), 11 deletions(-) diff --git a/Documentation/ftrace.txt b/Documentation/ftrace.txt index 9cc4d685dde..a1b58777839 100644 --- a/Documentation/ftrace.txt +++ b/Documentation/ftrace.txt @@ -94,7 +94,7 @@ of ftrace. Here is a list of some of the key files: only be recorded if the latency is greater than the value in this file. (in microseconds) - trace_entries: This sets or displays the number of bytes each CPU + buffer_size_kb: This sets or displays the number of bytes each CPU buffer can hold. The tracer buffers are the same size for each CPU. The displayed number is the size of the CPU buffer and not total size of all buffers. The @@ -1299,13 +1299,13 @@ trace entries ------------- Having too much or not enough data can be troublesome in diagnosing -an issue in the kernel. The file trace_entries is used to modify +an issue in the kernel. The file buffer_size_kb is used to modify the size of the internal trace buffers. The number listed is the number of entries that can be recorded per CPU. To know the full size, multiply the number of possible CPUS with the number of entries. - # cat /debug/tracing/trace_entries + # cat /debug/tracing/buffer_size_kb 65620 Note, to modify this, you must have tracing completely disabled. To do that, @@ -1313,8 +1313,8 @@ echo "nop" into the current_tracer. If the current_tracer is not set to "nop", an EINVAL error will be returned. # echo nop > /debug/tracing/current_tracer - # echo 100000 > /debug/tracing/trace_entries - # cat /debug/tracing/trace_entries + # echo 100000 > /debug/tracing/buffer_size_kb + # cat /debug/tracing/buffer_size_kb 100045 @@ -1323,8 +1323,8 @@ are held in individual pages. It allocates the number of pages it takes to fulfill the request. If more entries may fit on the last page then they will be added. - # echo 1 > /debug/tracing/trace_entries - # cat /debug/tracing/trace_entries + # echo 1 > /debug/tracing/buffer_size_kb + # cat /debug/tracing/buffer_size_kb 85 This shows us that 85 entries can fit in a single page. @@ -1332,8 +1332,8 @@ This shows us that 85 entries can fit in a single page. The number of pages which will be allocated is limited to a percentage of available memory. Allocating too much will produce an error. - # echo 1000000000000 > /debug/tracing/trace_entries + # echo 1000000000000 > /debug/tracing/buffer_size_kb -bash: echo: write error: Cannot allocate memory - # cat /debug/tracing/trace_entries + # cat /debug/tracing/buffer_size_kb 85 diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 4bf070bb527..b42d42056fa 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3198,11 +3198,11 @@ static __init int tracer_init_debugfs(void) pr_warning("Could not create debugfs " "'trace_pipe' entry\n"); - entry = debugfs_create_file("trace_entries", 0644, d_tracer, + entry = debugfs_create_file("buffer_size_kb", 0644, d_tracer, &global_trace, &tracing_entries_fops); if (!entry) pr_warning("Could not create debugfs " - "'trace_entries' entry\n"); + "'buffer_size_kb' entry\n"); entry = debugfs_create_file("trace_marker", 0220, d_tracer, NULL, &tracing_mark_fops); From 1696b2b0f44a8d42f3e6b1ea90c21790871c04d9 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 13 Nov 2008 00:09:35 -0500 Subject: [PATCH 2/6] ftrace: show buffer size in kilobytes Impact: change the units of buffer_size_kb to kilobytes This patch changes the units of the buffer_size_kb file to kilobytes. Reading and writing to the file uses kilobytes as units. To help users to know what units are used, the output of the file now looks like: # cat /debug/tracing/buffer_size_kb 1408 Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- Documentation/ftrace.txt | 22 +++++----------------- kernel/trace/trace.c | 5 ++++- 2 files changed, 9 insertions(+), 18 deletions(-) diff --git a/Documentation/ftrace.txt b/Documentation/ftrace.txt index a1b58777839..6d3fe4cdf92 100644 --- a/Documentation/ftrace.txt +++ b/Documentation/ftrace.txt @@ -94,10 +94,10 @@ of ftrace. Here is a list of some of the key files: only be recorded if the latency is greater than the value in this file. (in microseconds) - buffer_size_kb: This sets or displays the number of bytes each CPU + buffer_size_kb: This sets or displays the number of kilobytes each CPU buffer can hold. The tracer buffers are the same size for each CPU. The displayed number is the size of the - CPU buffer and not total size of all buffers. The + CPU buffer and not total size of all buffers. The trace buffers are allocated in pages (blocks of memory that the kernel uses for allocation, usually 4 KB in size). If the last page allocated has room for more bytes @@ -1306,28 +1306,16 @@ the full size, multiply the number of possible CPUS with the number of entries. # cat /debug/tracing/buffer_size_kb -65620 +1408 (units kilobytes) Note, to modify this, you must have tracing completely disabled. To do that, echo "nop" into the current_tracer. If the current_tracer is not set to "nop", an EINVAL error will be returned. # echo nop > /debug/tracing/current_tracer - # echo 100000 > /debug/tracing/buffer_size_kb + # echo 10000 > /debug/tracing/buffer_size_kb # cat /debug/tracing/buffer_size_kb -100045 - - -Notice that we echoed in 100,000 but the size is 100,045. The entries -are held in individual pages. It allocates the number of pages it takes -to fulfill the request. If more entries may fit on the last page -then they will be added. - - # echo 1 > /debug/tracing/buffer_size_kb - # cat /debug/tracing/buffer_size_kb -85 - -This shows us that 85 entries can fit in a single page. +10000 (units kilobytes) The number of pages which will be allocated is limited to a percentage of available memory. Allocating too much will produce an error. diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b42d42056fa..d664aae2e10 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2905,7 +2905,7 @@ tracing_entries_read(struct file *filp, char __user *ubuf, char buf[64]; int r; - r = sprintf(buf, "%lu\n", tr->entries); + r = sprintf(buf, "%lu\n", tr->entries >> 10); return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); } @@ -2945,6 +2945,9 @@ tracing_entries_write(struct file *filp, const char __user *ubuf, atomic_inc(&max_tr.data[cpu]->disabled); } + /* value is in KB */ + val <<= 10; + if (val != global_trace.entries) { ret = ring_buffer_resize(global_trace.buffer, val); if (ret < 0) { From ee6bce52276c0717ed3e63296e5d9465d339e923 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 12 Nov 2008 17:52:37 -0500 Subject: [PATCH 3/6] ftrace: rename iter_ctrl to trace_options Impact: rename file /debug/tracing/iter_ctrl to /debug/tracing/trace_options The original ftrace had a file called "iter_ctrl" that would control the way the output was iterated. But this file grew into a catch all for different trace options. This patch renames the file from iter_ctrl to trace_options to reflect this change. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- Documentation/ftrace.txt | 14 +++++++------- kernel/trace/trace.c | 18 +++++++++--------- 2 files changed, 16 insertions(+), 16 deletions(-) diff --git a/Documentation/ftrace.txt b/Documentation/ftrace.txt index 6d3fe4cdf92..753f4de4b17 100644 --- a/Documentation/ftrace.txt +++ b/Documentation/ftrace.txt @@ -82,7 +82,7 @@ of ftrace. Here is a list of some of the key files: tracer is not adding more data, they will display the same information every time they are read. - iter_ctrl: This file lets the user control the amount of data + trace_options: This file lets the user control the amount of data that is displayed in one of the above output files. @@ -316,23 +316,23 @@ The above is mostly meaningful for kernel developers. The rest is the same as the 'trace' file. -iter_ctrl ---------- +trace_options +------------- -The iter_ctrl file is used to control what gets printed in the trace +The trace_options file is used to control what gets printed in the trace output. To see what is available, simply cat the file: - cat /debug/tracing/iter_ctrl + cat /debug/tracing/trace_options print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \ noblock nostacktrace nosched-tree To disable one of the options, echo in the option prepended with "no". - echo noprint-parent > /debug/tracing/iter_ctrl + echo noprint-parent > /debug/tracing/trace_options To enable an option, leave off the "no". - echo sym-offset > /debug/tracing/iter_ctrl + echo sym-offset > /debug/tracing/trace_options Here are the available options: diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d664aae2e10..240423a9d1a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -204,7 +204,7 @@ static DEFINE_MUTEX(trace_types_lock); /* trace_wait is a waitqueue for tasks blocked on trace_poll */ static DECLARE_WAIT_QUEUE_HEAD(trace_wait); -/* trace_flags holds iter_ctrl options */ +/* trace_flags holds trace_options default values */ unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK; /** @@ -2411,7 +2411,7 @@ static struct file_operations tracing_cpumask_fops = { }; static ssize_t -tracing_iter_ctrl_read(struct file *filp, char __user *ubuf, +tracing_trace_options_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { char *buf; @@ -2448,7 +2448,7 @@ tracing_iter_ctrl_read(struct file *filp, char __user *ubuf, } static ssize_t -tracing_iter_ctrl_write(struct file *filp, const char __user *ubuf, +tracing_trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { char buf[64]; @@ -2493,8 +2493,8 @@ tracing_iter_ctrl_write(struct file *filp, const char __user *ubuf, static struct file_operations tracing_iter_fops = { .open = tracing_open_generic, - .read = tracing_iter_ctrl_read, - .write = tracing_iter_ctrl_write, + .read = tracing_trace_options_read, + .write = tracing_trace_options_write, }; static const char readme_msg[] = @@ -2508,9 +2508,9 @@ static const char readme_msg[] = "# echo sched_switch > /debug/tracing/current_tracer\n" "# cat /debug/tracing/current_tracer\n" "sched_switch\n" - "# cat /debug/tracing/iter_ctrl\n" + "# cat /debug/tracing/trace_options\n" "noprint-parent nosym-offset nosym-addr noverbose\n" - "# echo print-parent > /debug/tracing/iter_ctrl\n" + "# echo print-parent > /debug/tracing/trace_options\n" "# echo 1 > /debug/tracing/tracing_enabled\n" "# cat /debug/tracing/trace > /tmp/trace.txt\n" "echo 0 > /debug/tracing/tracing_enabled\n" @@ -3148,10 +3148,10 @@ static __init int tracer_init_debugfs(void) if (!entry) pr_warning("Could not create debugfs 'tracing_enabled' entry\n"); - entry = debugfs_create_file("iter_ctrl", 0644, d_tracer, + entry = debugfs_create_file("trace_options", 0644, d_tracer, NULL, &tracing_iter_fops); if (!entry) - pr_warning("Could not create debugfs 'iter_ctrl' entry\n"); + pr_warning("Could not create debugfs 'trace_options' entry\n"); entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer, NULL, &tracing_cpumask_fops); From 12ef7d448613ead2babd41c3ebfa1fe03c20edef Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 12 Nov 2008 17:52:38 -0500 Subject: [PATCH 4/6] ftrace: CPU buffer start annotation clean ups Impact: better handling of CPU buffer start annotation Because of the confusion with the per CPU buffers wrapping where one CPU might be more active at the end of the trace than the other CPUs causing that one CPU to have a shorter history. Kernel developers were confused by the "missing" data of that one CPU at the beginning of the trace output. An annotation was added to the trace output to show that the buffer had started: # tracer: function # # TASK-PID CPU# TIMESTAMP FUNCTION # | | | | | ##### CPU 3 buffer started #### -0 [003] 158.192959: smp_apic_timer_interrupt [...] -0 [003] 161.556520: default_idle ##### CPU 1 buffer started #### -0 [001] 161.592494: hrtimer_force_reprogram [etc] But this annotation gets a bit messy when tracers do not fill the buffers. This patch does a couple of things: One) it adds a flag to trace_options to disable these annotations Two) it does not annotate if the tracer did not overflow its buffer. This makes the output much cleaner. Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/trace.c | 16 +++++++++++++++- kernel/trace/trace.h | 1 + 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 240423a9d1a..4a904623e05 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -205,7 +205,8 @@ static DEFINE_MUTEX(trace_types_lock); static DECLARE_WAIT_QUEUE_HEAD(trace_wait); /* trace_flags holds trace_options default values */ -unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK; +unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK | + TRACE_ITER_ANNOTATE; /** * trace_wake_up - wake up tasks waiting for trace input @@ -261,6 +262,7 @@ static const char *trace_options[] = { #ifdef CONFIG_BRANCH_TRACER "branch", #endif + "annotate", NULL }; @@ -1113,6 +1115,7 @@ void tracing_stop_function_trace(void) enum trace_file_type { TRACE_FILE_LAT_FMT = 1, + TRACE_FILE_ANNOTATE = 2, }; static void trace_iterator_increment(struct trace_iterator *iter, int cpu) @@ -1532,6 +1535,12 @@ static void test_cpu_buff_start(struct trace_iterator *iter) { struct trace_seq *s = &iter->seq; + if (!(trace_flags & TRACE_ITER_ANNOTATE)) + return; + + if (!(iter->iter_flags & TRACE_FILE_ANNOTATE)) + return; + if (cpu_isset(iter->cpu, iter->started)) return; @@ -2132,6 +2141,11 @@ __tracing_open(struct inode *inode, struct file *file, int *ret) iter->trace = current_trace; iter->pos = -1; + /* Annotate start of buffers if we had overruns */ + if (ring_buffer_overruns(iter->tr->buffer)) + iter->iter_flags |= TRACE_FILE_ANNOTATE; + + for_each_tracing_cpu(cpu) { iter->buffer_iter[cpu] = diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 9e015f5bea1..790ea8c0e1f 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -473,6 +473,7 @@ enum trace_iterator_flags { #ifdef CONFIG_BRANCH_TRACER TRACE_ITER_BRANCH = 0x1000, #endif + TRACE_ITER_ANNOTATE = 0x2000, }; /* From ee51a1de7e3837577412be269e0100038068e691 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 13 Nov 2008 14:58:31 +0100 Subject: [PATCH 5/6] tracing: fix mmiotrace resizing crash Pekka reported a crash when resizing the mmiotrace tracer (if only mmiotrace is enabled). This happens because in that case we do not allocate the max buffer, but we try to use it. Make ring_buffer_resize() idempotent against NULL buffers. Reported-by: Pekka Paalanen Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 231db209fa8..036456cbb4f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -538,6 +538,12 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) LIST_HEAD(pages); int i, cpu; + /* + * Always succeed at resizing a non-existent buffer: + */ + if (!buffer) + return size; + size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); size *= BUF_PAGE_SIZE; buffer_size = buffer->pages * BUF_PAGE_SIZE; From b3535c6390f27d04273e4eee0bc687f171fbf5f4 Mon Sep 17 00:00:00 2001 From: walimis Date: Fri, 14 Nov 2008 00:21:02 +0800 Subject: [PATCH 6/6] ftrace: remove unnecessary if condition of __unregister_ftrace_function Because it has goto out before ftrace_list == &ftrace_list_end, that's to say, we never meet this condition. Signed-off-by: walimis Acked-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/trace/ftrace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index beb21a51e1e..54cb9a7d15e 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -179,8 +179,7 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops) if (ftrace_enabled) { /* If we only have one func left, then call that directly */ - if (ftrace_list == &ftrace_list_end || - ftrace_list->next == &ftrace_list_end) + if (ftrace_list->next == &ftrace_list_end) ftrace_trace_function = ftrace_list->func; }