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The commit (in linux-tip) c2931e05ec5965597cbfb79ad332d4a29aeceb23
( ftrace: return an error when setting a nonexistent tracer )
added useful code that would error when a bad tracer was written into
the current_tracer file.
But this had a bug if the amount written was more than the amount read by
that code. The first iteration would set the tracer correctly, but since
it did not consume the rest of what was written (usually whitespace), the
userspace utility would continue to write what was not consumed. This
second iteration would fail to find a tracer and return -EINVAL. Funny
thing is that the tracer would have already been set.
This patch just consumes all the data that is written to the file.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: build fix on Alpha
When tracing is enabled, some arch have included <linux/irqflags.h>
on their <asm/system.h> but others like alpha or m68k don't.
Build error on alpha:
kernel/trace/trace.c: In function 'tracing_cpumask_write':
kernel/trace/trace.c:2145: error: implicit declaration of function 'raw_local_irq_disable'
kernel/trace/trace.c:2162: error: implicit declaration of function 'raw_local_irq_enable'
Tested on Alpha through a cross-compiler (should correct a similar issue on m68k).
Reported-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: build fix
If the boot tracer is selected but not the sched_switch,
there will be a build failure:
kernel/built-in.o: In function `boot_trace_init':
trace_boot.c:(.text+0x5ee38): undefined reference to `sched_switch_trace'
kernel/built-in.o: In function `disable_boot_trace':
(.text+0x5eee1): undefined reference to `tracing_stop_cmdline_record'
kernel/built-in.o: In function `enable_boot_trace':
(.text+0x5ef11): undefined reference to `tracing_start_cmdline_record'
This patch fixes it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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A powerpc ppc64_defconfig build produces these warnings:
kernel/trace/ring_buffer.c: In function 'rb_add_time_stamp':
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 2 has type 'u64'
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 3 has type 'u64'
kernel/trace/ring_buffer.c:969: warning: format '%llu' expects type 'long long unsigned int', but argument 4 has type 'u64'
Just cast the u64s to unsigned long long like we do everywhere else.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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this warning:
kernel/trace/ftrace.c:189: warning: ‘frozen_record_count’ defined but not used
triggers because frozen_record_count is only used in the KCONFIG_MARKERS
case. Move the variable it there.
Alas, this frozen-record facility seems to have little use. The
frozen_record_count variable is not used by anything, nor the flags.
So this section might need a bit of dead-code-removal care as well.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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fix:
kernel/trace/ftrace.c: In function 'ftrace_release':
kernel/trace/ftrace.c:271: error: implicit declaration of function 'ftrace_release_hash'
release_hash is not needed without dftraced.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The ftrace hash was used by the ftrace_daemon code. The record ip function
would place the calling address (ip) into the hash. The daemon would later
read the hash and modify that code.
The hash complicates the code. This patch removes it.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The arch dependent function ftrace_mcount_set was only used by the daemon
start up code. This patch removes it.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The ftrace daemon is complex and error prone. This patch strips it out
of the code.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Add ftrace warn on to disable ftrace as well as report a warning.
[ Thanks to Andrew Morton for suggesting using the WARN_ON return value ]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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When an anomaly is detected, we need a way to completely disable
ftrace. Right now we have two functions: ftrace_kill and ftrace_kill_atomic.
The ftrace_kill tries to do it in a "nice" way by converting everything
back to a nop.
The "nice" way is dangerous itself, so this patch removes it and only
has the "atomic" version, which is all that is needed.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Have the ftrace_modify_code return error values:
-EFAULT on error of reading the address
-EINVAL if what is read does not match what it expected
-EPERM if the write fails to update after a successful match.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The pages of a buffer was originally pointing to the page struct, it
now points to the page address. The freeing of the page still uses
the page frame free "__free_page" instead of the correct free_page to
the address.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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We seem to have plenty tracers, lets create a menu and not clutter
the already cluttered debug menu more.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Frédéric Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The stack trace API does not record if the stack is not on the current
task's stack. That is, if the stack is the interrupt stack or NMI stack,
the output does not show. Also, the size of those stacks are not
consistent with the size of the thread stack, this makes the calculation
of the stack size usually bogus.
This all confuses the stack tracer. I unfortunately do not have time to
fix all these problems, but this patch does record the worst stack when
the stack pointer is on the tasks stack (instead of bogus numbers).
The patch simply returns if the stack pointer is not on the task's stack.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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To avoid further confusion between the ftrace infrastructure and the
function tracer. This patch renames the "ftrace" function tracer
to "function".
Now in available_tracers, instead of "ftrace" there will be "function".
This makes more sense, since people will not know exactly what the
"ftrace" tracer does.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Due to confusion between the ftrace infrastructure and the gcc profiling
tracer "ftrace", this patch renames the config options from FTRACE to
FUNCTION_TRACER. The other two names that are offspring from FTRACE
DYNAMIC_FTRACE and FTRACE_MCOUNT_RECORD will stay the same.
This patch was generated mostly by script, and partially by hand.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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A lot of tracers have HAVE_FTRACE as a dependent config where it
really should not. The HAVE_FTRACE is a misnomer (soon to be fixed)
and describes if the architecture has the function tracer (mcount)
implemented. The ftrace infrastructure is implemented in all archs.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The x86 architecture uses a static recording of mcount caller locations
and is not affected by this patch.
For architectures still using the dynamic ftrace daemon, this patch is
critical. It removes the race between the recording of a function that
calls mcount, the unloading of a module, and the ftrace daemon updating
the call sites.
This patch adds the releasing of the hash functions that the daemon uses
to update the mcount call sites. When a module is unloaded, not only
are the replaced call site table update, but now so is the hash recorded
functions that the ftrace daemon will use.
Again, architectures that implement MCOUNT_RECORD are not affected by
this (which currently only x86 has).
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Improve the help text of the boot tracer.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Improve the help text that is displayed for CONFIG_STACK_TRACER.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Remove the runtime BUG_ON and change to a compile-time check in
the macro that calls the hex format routine
[Noticed by Joe Perches]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Fix the output of ftrace in hex mode as the hi/lo nibbles are output in
reverse order. Without this patch, the output of ftrace is:
raw mode : 6474 0 141531612444 0 140 + 6402 120 S
hex mode : 000091a4 00000000 000000023f1f50c1 00000000 c8 000000b2 00009120 87 ffff00c8 00000035
There is an inversion on ouput hex(6474) is 194a
[based on a patch by Philippe Reynes <tremyfr@yahoo.fr>]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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When printing nanoseconds, the right printk format string is %09 not %06...
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Frédéric Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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When one try to set a nonexistent tracer, no error is returned
as if the name of the tracer was correct.
We should return -EINVAL.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Now that the ring buffer is reentrant, some of the ftrace tracers
(sched_swich, debugging traces) can also be reentrant.
Note: Never make the function tracer reentrant, that can cause
recursion problems all over the kernel. The function tracer
must disable reentrancy.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch replaces the local_irq_save/restore with preempt_disable/
enable. This allows for interrupts to enter while recording.
To write to the ring buffer, you must reserve data, and then
commit it. During this time, an interrupt may call a trace function
that will also record into the buffer before the commit is made.
The interrupt will reserve its entry after the first entry, even
though the first entry did not finish yet.
The time stamp delta of the interrupt entry will be zero, since
in the view of the trace, the interrupt happened during the
first field anyway.
Locking still takes place when the tail/write moves from one page
to the next. The reader always takes the locks.
A new page pointer is added, called the commit. The write/tail will
always point to the end of all entries. The commit field will
point to the last committed entry. Only this commit entry may
update the write time stamp.
The reader can only go up to the commit. It cannot go past it.
If a lot of interrupts come in during a commit that fills up the
buffer, and it happens to make it all the way around the buffer
back to the commit, then a warning is printed and new events will
be dropped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Remove the global head and tail indexes and move them into the
page header. Each page will now keep track of where the last
write and read was made. We also rename the head and tail to read
and write for better clarification.
This patch is needed for future enhancements to move the ring buffer
to a lockless solution.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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At this time, only built-in initcalls interest us.
We can't really produce a relevant graph if we include
the modules initcall too.
I had good results after this patch (see svg in attachment).
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The assigning of the pc counter is in the wrong spot in the
check_critical_timing function. The pc variable is used in the
out jump.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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My original patch had a compile bug when NUMA was configured. I
referenced cpu when it should have been cpu_buffer->cpu.
Ingo quickly fixed this bug by replacing cpu with 'i' because that
was the loop counter. Unfortunately, the 'i' was the counter of
pages, not CPUs. This caused a crash when the number of pages allocated
for the buffers exceeded the number of pages, which would usually
be the case.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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After some initcall traces, some initcall names may be inconsistent.
That's because these functions will disappear from the .init section
and also their name from the symbols table.
So we have to copy the name of the function in a buffer large enough
during the trace appending. It is not costly for the ring_buffer because
the number of initcall entries is commonly not really large.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Change the boot tracer printing to make it parsable for
the scripts/bootgraph.pl script.
We have now to output two lines for each initcall, according to the
printk in do_one_initcall() in init/main.c
We need now the call's time and the return's time.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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fix:
kernel/trace/ring_buffer.c: In function ‘rb_allocate_pages’:
kernel/trace/ring_buffer.c:235: error: ‘cpu’ undeclared (first use in this function)
kernel/trace/ring_buffer.c:235: error: (Each undeclared identifier is reported only once
kernel/trace/ring_buffer.c:235: error: for each function it appears in.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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With the new ring buffer infrastructure in ftrace, I'm trying to make
ftrace a little more light weight.
This patch converts a lot of the local_irq_save/restore into
preempt_disable/enable. The original preempt count in a lot of cases
has to be sent in as a parameter so that it can be recorded correctly.
Some places were recording it incorrectly before anyway.
This is also laying the ground work to make ftrace a little bit
more reentrant, and remove all locking. The function tracers must
still protect from reentrancy.
Note: All the function tracers must be careful when using preempt_disable.
It must do the following:
resched = need_resched();
preempt_disable_notrace();
[...]
if (resched)
preempt_enable_no_resched_notrace();
else
preempt_enable_notrace();
The reason is that if this function traces schedule() itself, the
preempt_enable_notrace() will cause a schedule, which will lead
us into a recursive failure.
If we needed to reschedule before calling preempt_disable, we
should have already scheduled. Since we did not, this is most
likely that we should not and are probably inside a schedule
function.
If resched was not set, we still need to catch the need resched
flag being set when preemption was off and the if case at the
end will catch that for us.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The current method of overlaying the page frame as the buffer page pointer
can be very dangerous and limits our ability to do other things with
a page from the buffer, like send it off to disk.
This patch allocates the buffer_page instead of overlaying the page's
page frame. The use of the buffer_page has hardly changed due to this.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The mmiotrace map had a bug that would typecast the entry from
the trace to the wrong type. That is a known danger of C typecasts,
there's absolutely zero checking done on them.
Help that problem a bit by using a GCC extension to implement a
type filter that restricts the types that a trace record can be
cast into, and by adding a dynamic check (in debug mode) to verify
the type of the entry.
This patch adds a macro to assign all entries of ftrace using the type
of the variable and checking the entry id. The typecasts are now done
in the macro for only those types that it knows about, which should
be all the types that are allowed to be read from the tracer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Correct the value's type of trace_empty function
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The old "lock always" scheme had issues with lockdep, and was not very
efficient anyways.
This patch does a new design to be partially lockless on writes.
Writes will add new entries to the per cpu pages by simply disabling
interrupts. When a write needs to go to another page than it will
grab the lock.
A new "read page" has been added so that the reader can pull out a page
from the ring buffer to read without worrying about the writer writing over
it. This allows us to not take the lock for all reads. The lock is
now only taken when a read needs to go to a new page.
This is far from lockless, and interrupts still need to be disabled,
but it is a step towards a more lockless solution, and it also
solves a lot of the issues that were noticed by the first conversion
of ftrace to the ring buffers.
Note: the ring_buffer_{un}lock API has been removed.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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The raw_local_irq_save causes issues with lockdep. We don't need it
so replace them with local_irq_save.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch adapts the boot tracer to the new type of the
print_line callback.
It still relays entries it doesn't support to default output
functions.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Adapt mmiotrace to the new print_line type.
By default, it ignores (and consumes) types it doesn't support.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch fixes a bug which break the pipe when the seq is empty.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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We need a kind of disambiguation when a print_line callback
returns 0.
_There is not enough space to print all the entry.
Please flush the seq and retry.
_I can't handle this type of entry
This patch changes the type of this callback for better information.
Also some changes have been made in this V2.
_ Only relay to default functions after the print_line callback fails.
_ This patch doesn't fix the issue with the broken pipe (see patch 2/4 for that)
Some things are still in discussion:
_ Find better names for the enum print_line_t values
_ Change the type of print_trace_line into boolean.
Patches to change that can be sent later.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Now that the underlining ring buffer for ftrace now hold variable length
entries, we can take advantage of this by only storing the size of the
actual event into the buffer. This happens to increase the number of
entries in the buffer dramatically.
We can also get rid of the "trace_cont" operation, but I'm keeping that
until we have no more users. Some of the ftrace tracers can now change
their code to adapt to this new feature.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch ports ftrace over to the new ring buffer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Mathieu Desnoyers pointed out that the freeing of the page frame needs
to be reset otherwise we might trigger BUG_ON in the page free code.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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If for some strange reason the buffer_page gets bigger, or the page struct
gets smaller, I want to know this ASAP. The best way is to not let the
kernel compile.
This patch adds code to test the size of the struct buffer_page against the
page struct and will cause compile issues if the buffer_page ever gets bigger
than the page struct.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This is a unified tracing buffer that implements a ring buffer that
hopefully everyone will eventually be able to use.
The events recorded into the buffer have the following structure:
struct ring_buffer_event {
u32 type:2, len:3, time_delta:27;
u32 array[];
};
The minimum size of an event is 8 bytes. All events are 4 byte
aligned inside the buffer.
There are 4 types (all internal use for the ring buffer, only
the data type is exported to the interface users).
RINGBUF_TYPE_PADDING: this type is used to note extra space at the end
of a buffer page.
RINGBUF_TYPE_TIME_EXTENT: This type is used when the time between events
is greater than the 27 bit delta can hold. We add another
32 bits, and record that in its own event (8 byte size).
RINGBUF_TYPE_TIME_STAMP: (Not implemented yet). This will hold data to
help keep the buffer timestamps in sync.
RINGBUF_TYPE_DATA: The event actually holds user data.
The "len" field is only three bits. Since the data must be
4 byte aligned, this field is shifted left by 2, giving a
max length of 28 bytes. If the data load is greater than 28
bytes, the first array field holds the full length of the
data load and the len field is set to zero.
Example, data size of 7 bytes:
type = RINGBUF_TYPE_DATA
len = 2
time_delta: <time-stamp> - <prev_event-time-stamp>
array[0..1]: <7 bytes of data> <1 byte empty>
This event is saved in 12 bytes of the buffer.
An event with 82 bytes of data:
type = RINGBUF_TYPE_DATA
len = 0
time_delta: <time-stamp> - <prev_event-time-stamp>
array[0]: 84 (Note the alignment)
array[1..14]: <82 bytes of data> <2 bytes empty>
The above event is saved in 92 bytes (if my math is correct).
82 bytes of data, 2 bytes empty, 4 byte header, 4 byte length.
Do not reference the above event struct directly. Use the following
functions to gain access to the event table, since the
ring_buffer_event structure may change in the future.
ring_buffer_event_length(event): get the length of the event.
This is the size of the memory used to record this
event, and not the size of the data pay load.
ring_buffer_time_delta(event): get the time delta of the event
This returns the delta time stamp since the last event.
Note: Even though this is in the header, there should
be no reason to access this directly, accept
for debugging.
ring_buffer_event_data(event): get the data from the event
This is the function to use to get the actual data
from the event. Note, it is only a pointer to the
data inside the buffer. This data must be copied to
another location otherwise you risk it being written
over in the buffer.
ring_buffer_lock: A way to lock the entire buffer.
ring_buffer_unlock: unlock the buffer.
ring_buffer_alloc: create a new ring buffer. Can choose between
overwrite or consumer/producer mode. Overwrite will
overwrite old data, where as consumer producer will
throw away new data if the consumer catches up with the
producer. The consumer/producer is the default.
ring_buffer_free: free the ring buffer.
ring_buffer_resize: resize the buffer. Changes the size of each cpu
buffer. Note, it is up to the caller to provide that
the buffer is not being used while this is happening.
This requirement may go away but do not count on it.
ring_buffer_lock_reserve: locks the ring buffer and allocates an
entry on the buffer to write to.
ring_buffer_unlock_commit: unlocks the ring buffer and commits it to
the buffer.
ring_buffer_write: writes some data into the ring buffer.
ring_buffer_peek: Look at a next item in the cpu buffer.
ring_buffer_consume: get the next item in the cpu buffer and
consume it. That is, this function increments the head
pointer.
ring_buffer_read_start: Start an iterator of a cpu buffer.
For now, this disables the cpu buffer, until you issue
a finish. This is just because we do not want the iterator
to be overwritten. This restriction may change in the future.
But note, this is used for static reading of a buffer which
is usually done "after" a trace. Live readings would want
to use the ring_buffer_consume above, which will not
disable the ring buffer.
ring_buffer_read_finish: Finishes the read iterator and reenables
the ring buffer.
ring_buffer_iter_peek: Look at the next item in the cpu iterator.
ring_buffer_read: Read the iterator and increment it.
ring_buffer_iter_reset: Reset the iterator to point to the beginning
of the cpu buffer.
ring_buffer_iter_empty: Returns true if the iterator is at the end
of the cpu buffer.
ring_buffer_size: returns the size in bytes of each cpu buffer.
Note, the real size is this times the number of CPUs.
ring_buffer_reset_cpu: Sets the cpu buffer to empty
ring_buffer_reset: sets all cpu buffers to empty
ring_buffer_swap_cpu: swaps a cpu buffer from one buffer with a
cpu buffer of another buffer. This is handy when you
want to take a snap shot of a running trace on just one
cpu. Having a backup buffer, to swap with facilitates this.
Ftrace max latencies use this.
ring_buffer_empty: Returns true if the ring buffer is empty.
ring_buffer_empty_cpu: Returns true if the cpu buffer is empty.
ring_buffer_record_disable: disable all cpu buffers (read only)
ring_buffer_record_disable_cpu: disable a single cpu buffer (read only)
ring_buffer_record_enable: enable all cpu buffers.
ring_buffer_record_enabl_cpu: enable a single cpu buffer.
ring_buffer_entries: The number of entries in a ring buffer.
ring_buffer_overruns: The number of entries removed due to writing wrap.
ring_buffer_time_stamp: Get the time stamp used by the ring buffer
ring_buffer_normalize_time_stamp: normalize the ring buffer time stamp
into nanosecs.
I still need to implement the GTOD feature. But we need support from
the cpu frequency infrastructure. But this can be done at a later
time without affecting the ring buffer interface.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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It is possible that the testing thread in the ftrace wakeup test does not
run before we stop the trace. This will cause the trace to fail since nothing
will be in the buffers.
This patch adds a small wait in the wakeup test to allow for the woken task
to run and be traced.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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