Namhyung Kim [Mon, 23 Apr 2012 01:11:57 +0000 (10:11 +0900)]
tracing: Check return value of tracing_dentry_percpu()
If tracing_dentry_percpu() failed, tracing_init_debugfs_percpu()
will try to create each cpu directories on debugfs' root directory
as d_percpu is NULL.
Steven Rostedt [Wed, 16 May 2012 23:46:32 +0000 (19:46 -0400)]
ring-buffer: Reset head page before running self test
When the ring buffer does its consistency test on itself, it
removes the head page, runs the tests, and then adds it back
to what the "head_page" pointer was. But because the head_page
pointer may lack behind the real head page (held by the link
list pointer). The reset may be incorrect.
Instead, if the head_page exists (it does not on first allocation)
reset it back to the real head page before running the consistency
tests. Then it will be put back to its original location after
the tests are complete.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Mon, 14 May 2012 21:02:33 +0000 (17:02 -0400)]
ring-buffer: Add integrity check at end of iter read
There use to be ring buffer integrity checks after updating the
size of the ring buffer. But now that the ring buffer can modify
the size while the system is running, the integrity checks were
removed, as they require the ring buffer to be disabed to perform
the check.
Move the integrity check to the reading of the ring buffer via the
iterator reads (the "trace" file). As reading via an iterator requires
disabling the ring buffer, it is a perfect place to have it.
If the ring buffer happens to be disabled when updating the size,
we still perform the integrity check.
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ring-buffer: Make addition of pages in ring buffer atomic
This patch adds the capability to add new pages to a ring buffer
atomically while write operations are going on. This makes it possible
to expand the ring buffer size without reinitializing the ring buffer.
The new pages are attached between the head page and its previous page.
ring-buffer: Make removal of ring buffer pages atomic
This patch adds the capability to remove pages from a ring buffer
without destroying any existing data in it.
This is done by removing the pages after the tail page. This makes sure
that first all the empty pages in the ring buffer are removed. If the
head page is one in the list of pages to be removed, then the page after
the removed ones is made the head page. This removes the oldest data
from the ring buffer and keeps the latest data around to be read.
To do this in a non-racey manner, tracing is stopped for a very short
time while the pages to be removed are identified and unlinked from the
ring buffer. The pages are freed after the tracing is restarted to
minimize the time needed to stop tracing.
The context in which the pages from the per-cpu ring buffer are removed
runs on the respective CPU. This minimizes the events not traced to only
NMI trace contexts.
Steven Rostedt [Sat, 12 May 2012 03:28:49 +0000 (23:28 -0400)]
tracing: Clean up tracing_mark_write()
On gcc 4.5 the function tracing_mark_write() would give a warning
of page2 being uninitialized. This is due to a bug in gcc because
the logic prevents page2 from being used uninitialized, and
gcc 4.6+ does not complain (correctly).
Instead of adding a "unitialized" around page2, which could show
a bug later on, I combined page1 and page2 into an array map_pages[].
This binds the two and the two are modified according to nr_pages
(what gcc 4.5 seems to ignore). This no longer gives a warning with
gcc 4.5 nor with gcc 4.6.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Just press 'J' and see how many places jump to jump targets.
The hottest jump target appears in red, targets with more than one
source have a different color than single source jump targets.
Suggested-by: Arjan van de Ven <arjan@infradead.org> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-7452y0dmc02a20ooins7rn79@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
perf annotate browser: Count the numbers of jump sources to a target
Instead of simply marking an offset as a jump target. So that we can
implement a new feature: showing "jumpy" targets, I.e. addresses that
lots of places jump to.
Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-vc7b0u5yxgrubig0q61ayhxf@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Ingo Molnar [Fri, 11 May 2012 06:13:55 +0000 (08:13 +0200)]
Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core
Fixes and improvements for perf/core:
- perf_target: abstraction for --uid, --pid, --tid, --cpu, --all-cpus handling,
eliminating code duplicated in the tools, having constraints that apply to
all of them, from Namhyung Kim
- Fixes for handling fallback to cpu-clock on PPC, from David Ahern
- Fix for processing events with unknown size, from Jiri Olsa
- Compilation fix on 32-bit, from Jiri Olsa
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
David Ahern [Tue, 8 May 2012 16:49:49 +0000 (10:49 -0600)]
perf top: Update event name when falling back to cpu-clock
The 'perf top' command falls back to cpu-clock if the H/W cycles event
is not supported, but the event name is not updated leading to a
misleading header:
David Ahern [Tue, 8 May 2012 15:29:16 +0000 (09:29 -0600)]
perf stat: handle ENXIO error for perf_event_open
perf stat on PPC currently fails to run:
$ perf stat -- sleep 1
Error: open_counter returned with 6 (No such device or address). /bin/dmesg may provide additional information.
Fatal: Not all events could be opened.
The problem is that until 2.6.37 (behavior changed with commit b0a873e)
perf on PPC returns ENXIO when hw_perf_event_init() fails. With this
patch we get the expected behavior:
$ perf stat -v -- sleep 1
cycles event is not supported by the kernel.
stalled-cycles-frontend event is not supported by the kernel.
stalled-cycles-backend event is not supported by the kernel.
instructions event is not supported by the kernel.
branches event is not supported by the kernel.
branch-misses event is not supported by the kernel.
David Ahern [Tue, 8 May 2012 15:28:57 +0000 (09:28 -0600)]
perf record: Fix fallback to cpu-clock on ppc
perf-record on PPC is not falling back to cpu-clock:
$ perf record -ag -fo /tmp/perf.data -- sleep 1
Error: sys_perf_event_open() syscall returned with 6 (No such device or address). /bin/dmesg may provide additional information.
Fatal: No CONFIG_PERF_EVENTS=y kernel support configured?
The problem is that until 2.6.37 (behavior changed with commit b0a873e)
perf on PPC returns ENXIO when hw_perf_event_init() fails. With this
patch we get the expected behavior:
$ perf record -ag -fo /tmp/perf.data -v -- sleep 1
Old kernel, cannot exclude guest or host samples.
The cycles event is not supported, trying to fall back to cpu-clock-ticks
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.151 MB /tmp/perf.data (~6592 samples) ]
Peter Zijlstra [Tue, 8 May 2012 16:56:04 +0000 (18:56 +0200)]
sched, perf: Use a single callback into the scheduler
We can easily use a single callback for both sched-in and sched-out. This
reduces the code footprint in the scheduler path as well as removes
the PMU black spot otherwise present between the out and in callback.
Robert Richter [Mon, 2 Apr 2012 18:19:18 +0000 (20:19 +0200)]
perf/x86-ibs: Fix usage of IBS op current count
The value of IbsOpCurCnt rolls over when it reaches IbsOpMaxCnt. Thus,
it is reset to zero by hardware. To get the correct count we need to
add the max count to it in case we received an ibs sample (valid bit
set).
Robert Richter [Mon, 2 Apr 2012 18:19:17 +0000 (20:19 +0200)]
perf/x86-ibs: Catch spurious interrupts after stopping IBS
After disabling IBS there could be still incomming NMIs with samples
that even have the valid bit cleared. Mark all this NMIs as handled to
avoid spurious interrupt messages.
Robert Richter [Mon, 2 Apr 2012 18:19:16 +0000 (20:19 +0200)]
perf/x86-ibs: Implement workaround for IBS erratum #420
When disabling ibs there might be the case where hardware continuously
generates interrupts. This is described in erratum #420 (Instruction-
Based Sampling Engine May Generate Interrupt that Cannot Be Cleared).
To avoid this we must clear the counter mask first and then clear the
enable bit. This patch implements this.
See Revision Guide for AMD Family 10h Processors, Publication #41322.
Note: We now keep track of the last read ibs config value which is
then used to disable ibs. To update the config value we pass now a
pointer to the functions reading it.
Robert Richter [Mon, 2 Apr 2012 18:19:15 +0000 (20:19 +0200)]
perf/x86-ibs: Extend hw period that triggers overflow
If the last hw period is too short we might hit the irq handler which
biases the results. Thus try to have a max last period that triggers
the sw overflow.
Robert Richter [Mon, 2 Apr 2012 18:19:14 +0000 (20:19 +0200)]
perf/x86-ibs: Trigger overflow if remaining period is too small
There are cases where the remaining period is smaller than the minimal
possible value. In this case the counter is restarted with the minimal
period. This is of no use as the interrupt handler will trigger
immediately again and most likely hits itself. This biases the
results.
So, if the remaining period is within the min range, we better do not
restart the counter and instead trigger the overflow.
Robert Richter [Mon, 12 Mar 2012 11:54:32 +0000 (12:54 +0100)]
perf/x86-ibs: Precise event sampling with IBS for AMD CPUs
This patch adds support for precise event sampling with IBS. There are
two counting modes to count either cycles or micro-ops. If the
corresponding performance counter events (hw events) are setup with
the precise flag set, the request is redirected to the ibs pmu:
perf record -a -e cpu-cycles:p ... # use ibs op counting cycle count
perf record -a -e r076:p ... # same as -e cpu-cycles:p
perf record -a -e r0C1:p ... # use ibs op counting micro-ops
Each ibs sample contains a linear address that points to the
instruction that was causing the sample to trigger. With ibs we have
skid 0. Thus, ibs supports precise levels 1 and 2. Samples are marked
with the PERF_EFLAGS_EXACT flag set. In rare cases the rip is invalid
when IBS was not able to record the rip correctly. Then the
PERF_EFLAGS_EXACT flag is cleared and the rip is taken from pt_regs.
V2:
* don't drop samples in precise level 2 if rip is invalid, instead
support the PERF_EFLAGS_EXACT flag
Robert Richter [Mon, 2 Apr 2012 18:19:11 +0000 (20:19 +0200)]
perf/x86-ibs: Take instruction pointer from ibs sample
Each IBS sample contains a linear address of the instruction that
caused the sample to trigger. This address is more precise than the
rip that was taken from the interrupt handler's stack. Update the rip
with that address. We use this in the next patch to implement
precise-event sampling on AMD systems using IBS.
Robert Richter [Mon, 2 Apr 2012 18:19:10 +0000 (20:19 +0200)]
perf/x86-ibs: Fix frequency profiling
Fixing profiling at a fixed frequency, in this case the freq value and
sample period was setup incorrectly. Since sampling periods are
adjusted we also allow periods that have lower 4 bits set.
Another fix is the setup of the hw counter: If we modify
hwc->sample_period, we also need to update hwc->last_period and
hwc->period_left.
Robert Richter [Mon, 2 Apr 2012 18:19:08 +0000 (20:19 +0200)]
perf: Pass last sampling period to perf_sample_data_init()
We always need to pass the last sample period to
perf_sample_data_init(), otherwise the event distribution will be
wrong. Thus, modifiyng the function interface with the required period
as argument. So basically a pattern like this:
Robert Richter [Mon, 2 Apr 2012 18:19:07 +0000 (20:19 +0200)]
perf/x86-ibs: Fix update of period
The last sw period was not correctly updated on overflow and thus led
to wrong distribution of events. We always need to properly initialize
data.period in struct perf_sample_data.
Steven Rostedt [Wed, 9 May 2012 00:57:53 +0000 (20:57 -0400)]
tracing: Remove ftrace_disable/enable_cpu()
The ftrace_disable_cpu() and ftrace_enable_cpu() functions were
needed back before the ring buffer was lockless. Now that the
ring buffer is lockless (and has been for some time), these functions
serve no purpose, and unnecessarily slow down operations of the tracer.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Jiri Olsa [Wed, 25 Apr 2012 08:23:39 +0000 (10:23 +0200)]
tracing: Use seq_*_private interface for some seq files
It's appropriate to use __seq_open_private interface to open
some of trace seq files, because it covers all steps we are
duplicating in tracing code - zallocating the iterator and
setting it as seq_file's private.
Using this for following files:
trace
available_filter_functions
enabled_functions
Link: http://lkml.kernel.org/r/1335342219-2782-5-git-send-email-jolsa@redhat.com Signed-off-by: Jiri Olsa <jolsa@redhat.com>
[
Fixed warnings for:
kernel/trace/trace.c: In function '__tracing_open':
kernel/trace/trace.c:2418:11: warning: unused variable 'ret' [-Wunused-variable]
kernel/trace/trace.c:2417:19: warning: unused variable 'm' [-Wunused-variable]
]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Ingo Molnar [Tue, 8 May 2012 14:55:14 +0000 (16:55 +0200)]
Merge branch 'perf/annotate' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core
Perf annotate browser improvements:
- Get back the line separating the overheads from the disassembly, requested by
Peter Zijlstra, Linus agreed now that it is a solid line and more column real
state was harvested. Also it has the jump->arrow lines separated from it by
the address/jump target column.
- Don't change asm line color when toggling source code view. Requested by
Peter Zijlstra.
Current snapshot:
avtab_search_node
│ push %rbp
│ mov %rsp,%rbp
│ → callq mcount
│ movzwl 0x6(%rsi),%edx
│ and $0x7fff,%dx
│ test %rdi,%rdi
│ ↓ jne 20
0.42 │17:┌─→xor %eax,%eax
│19:│ leaveq
0.42 │ │← retq
│ │ nopl 0x0(%rax,%rax,1)
│20:│ mov (%rdi),%rax
0.08 │ │ test %rax,%rax
│ └──je 17
│ movzwl (%rsi),%ecx
│ movzwl 0x2(%rsi),%r9d
│ movzwl 0x4(%rsi),%r8d
│ movzwl %cx,%esi
│ movzwl %r9w,%r10d
│ shl $0x9,%esi
│ lea (%rsi,%r10,4),%esi
│ lea (%r8,%rsi,1),%esi
│ and 0x10(%rdi),%si
│ movzwl %si,%esi
│ mov (%rax,%rsi,8),%rax
1.01 │ test %rax,%rax
│ ↑ je 19
│ nopw 0x0(%rax,%rax,1)
3.19 │60: cmp %cx,(%rax)
│ ↓ jne 7e
0.08 │ cmp %r9w,0x2(%rax)
│ ↓ jne 7e
│ cmp %r8w,0x4(%rax)
│ ↓ jne 79
│ test %dx,0x6(%rax)
│ ↑ jne 19
│79: cmp %r8w,0x4(%rax)
83.45 │7e: ↑ ja 17
3.36 │ mov 0x10(%rax),%rax
7.98 │ test %rax,%rax
│ ↑ jne 60
│ leaveq
│ ← retq
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Just suppress the nop operands, future infrastructure that will record
the instruction lenght (and its contents) in struct ins will allow
rendering them as nopN, i.e. nop5 for a 5-byte nop.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-qddbeglfzqdlal8vj2yaj67y@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Namhyung Kim [Mon, 7 May 2012 05:09:03 +0000 (14:09 +0900)]
perf target: Consolidate target task/cpu checking
There are places that check whether target task/cpu is given or not and
some of them didn't check newly introduced uid or cpu list. Add and use
three of helper functions to treat them properly.
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com> Reviewed-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1336367344-28071-7-git-send-email-namhyung.kim@lge.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Namhyung Kim [Mon, 7 May 2012 05:09:02 +0000 (14:09 +0900)]
perf tools: Introduce perf_target__strerror()
The perf_target__strerror() sets @buf to a string that describes the
(perf_target-specific) error condition that is passed via @errnum.
This is similar to strerror_r() and does same thing if @errnum has a
standard errno value.
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com> Suggested-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Reviewed-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1336367344-28071-6-git-send-email-namhyung.kim@lge.com
[ committer note: No need to use PERF_ERRNO_TARGET__SUCCESS, use shorter idiom ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Namhyung Kim [Mon, 7 May 2012 05:09:00 +0000 (14:09 +0900)]
perf target: Introduce perf_target_errno
The perf_target_errno enumerations are used to indicate specific error
cases on perf target operations. It'd help libperf being a more generic
library.
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com> Suggested-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Reviewed-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1336367344-28071-4-git-send-email-namhyung.kim@lge.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Check if neither of --pid, --tid or --uid was specified and if so, set
system_wide appropriately.
Namhyung's patch would make using any of the above target specifiers
emit a warning in perf_target__validate, since it would see
target.system_wide set and one of the others as well.
So set system_wide after validation.
Suggested-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-6e4zrji1uw0rinfyoitl0wi4@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Jiri Olsa [Mon, 16 Apr 2012 18:42:51 +0000 (20:42 +0200)]
perf session: Fail on processing event with unknown size
Currently if we cannot decide the size of the event, we guess next
event possition by:
"... check alignment, and increment a single u64 in the hope
to catch on again 'soon'"
This usually ends up with segfault or endless loop. It's better
to admit the failure right away, then pretend nothing happened.
It makes the life easier ;)
Signed-off-by: Jiri Olsa <jolsa@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120416184251.GA11503@m.brq.redhat.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Namhyung Kim [Thu, 26 Apr 2012 05:15:22 +0000 (14:15 +0900)]
perf target: Split out perf_target handling code
For further work on perf_target, it'd be better off splitting the code
into a separate file.
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com> Reviewed-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1335417327-11796-9-git-send-email-namhyung.kim@lge.com
[ committer note: Fixed perl build by using stdbool and types.h in target.h ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The perf_target__validate function is used to check given PID/TID/UID/CPU
target options and warn if some combination is impossible. Also this can
make some arguments of parse_target_uid() function useless as it is checked
before the call via our new helper.
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com> Reviewed-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1335417327-11796-5-git-send-email-namhyung.kim@lge.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Namhyung Kim [Thu, 26 Apr 2012 05:15:15 +0000 (14:15 +0900)]
perf tools: Introduce struct perf_target
The perf_target struct will be used for taking care of cpu/thread maps
based on user's input. Since it is used on various subcommands it'd
better factoring it out.
Thanks to Arnaldo for suggesting the better name.
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com> Reviewed-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1335417327-11796-2-git-send-email-namhyung.kim@lge.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Steven Rostedt [Tue, 24 Apr 2012 20:31:07 +0000 (16:31 -0400)]
ftrace/x86: Remove the complex ftrace NMI handling code
As ftrace function tracing would require modifying code that could
be executed in NMI context, which is not stopped with stop_machine(),
ftrace had to do a complex algorithm with various stages of setup
and memory barriers to make it work.
With the new breakpoint method, this is no longer required. The changes
to the code can be done without any problem in NMI context, as well as
without stop machine altogether. Remove the complex code as it is
no longer needed.
Also, a lot of the notrace annotations could be removed from the
NMI code as it is now safe to trace them. With the exception of
do_nmi itself, which does some special work to handle running in
the debug stack. The breakpoint method can cause NMIs to double
nest the debug stack if it's not setup properly, and that is done
in do_nmi(), thus that function must not be traced.
(Note the arch sh may want to do the same)
Cc: Paul Mundt <lethal@linux-sh.org> Cc: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Tue, 16 Aug 2011 13:57:10 +0000 (09:57 -0400)]
ftrace/x86: Have arch x86_64 use breakpoints instead of stop machine
This method changes x86 to add a breakpoint to the mcount locations
instead of calling stop machine.
Now that iret can be handled by NMIs, we perform the following to
update code:
1) Add a breakpoint to all locations that will be modified
2) Sync all cores
3) Update all locations to be either a nop or call (except breakpoint
op)
4) Sync all cores
5) Remove the breakpoint with the new code.
6) Sync all cores
[
Added updates that Masami suggested:
Use unlikely(modifying_ftrace_code) in int3 trap to keep kprobes efficient.
Don't use NOTIFY_* in ftrace handler in int3 as it is not a notifier.
]
Cc: H. Peter Anvin <hpa@zytor.com> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
perf annotate browser: Show current jump, back or forward
Instead of trying to show the current loop by naively looking for the
next backward jump, just use 'j' to toggle showing arrows connecting
jump with its target.
And do it for forward jumps as well.
Loop detection requires more code to follow the flow control, etc.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-soahcn1lz2u4wxj31ch0594j@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The infrastructure is there to provide formatters for any instruction,
like the one I'll do for call functions to elide the address.
Further fixes on top of the first iteration:
- Sometimes a jump points to an offset with no instructions, make the
mark jump targets function handle that, for now just ignoring such
jump targets, more investigation is needed to figure out how to cope
with that.
- Handle jump targets that are outside the function, for now just don't
try to draw the connector arrow, right thing seems to be to mark this
jump with a -> (right arrow) and handle it like a callq.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Robert Richter [Thu, 5 Apr 2012 16:24:42 +0000 (18:24 +0200)]
perf/x86: Fix cmpxchg() usage in amd_put_event_constraints()
Now the return value of cmpxchg() is used to match an event. The
change removes the duplicate event comparison and traverses the list
until an event was removed. This also fixes the following warning:
arch/x86/kernel/cpu/perf_event_amd.c:170: warning: value computed is not used
perf annotate browser: Don't draw jump connectors for out of function jumps
As described in the previous patch. Next step is to properly label those
jumps by using a -> arrow, i.e. not backwards/forwards, and allow the
user to navigate to this other function when enter or -> is pressed.
Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-ax2sss463eu88wgl9ee8a6b6@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
A function name represents the pointer to it - no need to take the
address of it. (Fixing this helps us introduce some macro magic
around register_nmi_handler() in the future.)
Cc: Robert Richter <robert.richter@amd.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
ring-buffer: Add per_cpu ring buffer control files
Add a debugfs entry under per_cpu/ folder for each cpu called
buffer_size_kb to control the ring buffer size for each CPU
independently.
If the global file buffer_size_kb is used to set size, the individual
ring buffers will be adjusted to the given size. The buffer_size_kb will
report the common size to maintain backward compatibility.
If the buffer_size_kb file under the per_cpu/ directory is used to
change buffer size for a specific CPU, only the size of the respective
ring buffer is updated. When tracing/buffer_size_kb is read, it reports
'X' to indicate that sizes of per_cpu ring buffers are not equivalent.
Link: http://lkml.kernel.org/r/1328212844-11889-1-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Michael Rubin <mrubin@google.com> Cc: David Sharp <dhsharp@google.com> Cc: Justin Teravest <teravest@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Dan Carpenter [Fri, 20 Apr 2012 06:31:45 +0000 (09:31 +0300)]
tracing: Remove an unneeded check in trace_seq_buffer()
memcpy() returns a pointer to "bug". Hopefully, it's not NULL here or
we would already have Oopsed.
Link: http://lkml.kernel.org/r/20120420063145.GA22649@elgon.mountain Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt [Thu, 22 Sep 2011 18:01:55 +0000 (14:01 -0400)]
tracing: Add percpu buffers for trace_printk()
Currently, trace_printk() uses a single buffer to write into
to calculate the size and format needed to save the trace. To
do this safely in an SMP environment, a spin_lock() is taken
to only allow one writer at a time to the buffer. But this could
also affect what is being traced, and add synchronization that
would not be there otherwise.
Ideally, using percpu buffers would be useful, but since trace_printk()
is only used in development, having per cpu buffers for something
never used is a waste of space. Thus, the use of the trace_bprintk()
format section is changed to be used for static fmts as well as dynamic ones.
Then at boot up, we can check if the section that holds the trace_printk
formats is non-empty, and if it does contain something, then we
know a trace_printk() has been added to the kernel. At this time
the trace_printk per cpu buffers are allocated. A check is also
done at module load time in case a module is added that contains a
trace_printk().
Once the buffers are allocated, they are never freed. If you use
a trace_printk() then you should know what you are doing.
A buffer is made for each type of context:
normal
softirq
irq
nmi
The context is checked and the appropriate buffer is used.
This allows for totally lockless usage of trace_printk(),
and they no longer even disable interrupts.
Requested-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Otherwise cpu_active_mask will not set, which lead to other issue.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Konrad Eisele <konrad@gaisler.com> Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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