Commit Graph

6845 Commits

Author SHA1 Message Date
Arnaldo Carvalho de Melo 5cb725a972 perf annotate: Rename symbol__annotate() to symbol__disassemble()
This function will not annotate anything, it will just disassembly the
given map->dso and symbol.

It currently does this by parsing the output of 'objdump --disassemble',
but this could conceivably be done using a library or an offshot of
the kernel's instruction decoder (arch/x86/lib/inat.c), etc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-2xpfl4bfnrd6x584b390qok7@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-08-01 17:06:46 -03:00
Arnaldo Carvalho de Melo ce92834407 perf target: str_error_r() always returns the buffer it receives
So no need for checking if it uses the strerror_r() GNU variant error
reporting mechanism, i.e. if it returns a pointer to a immutable string
internal to glibc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: c8b5f2c96d ("tools: Introduce str_error_r()")
Link: http://lkml.kernel.org/n/tip-xr83cd4y4r3cn6tq6w4f59jb@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-29 11:54:35 -03:00
Arnaldo Carvalho de Melo 9955d0be16 perf annotate: Use pipe + fork instead of popen
We will need to redirect the stderr as well, so open code popen as
a starting point.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-k0zt9svg4bswiglem7ornts4@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-29 11:12:39 -03:00
Arnaldo Carvalho de Melo 7c48dcfd32 perf evsel: Introduce constructor for cycles event
That is the default used when no events is specified in tools, separate
it so that simpler tools that need no evlist can use it directly.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-67mwuthscwroz88x9pswcqyv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-28 18:33:20 -03:00
Arnaldo Carvalho de Melo 4e3ba8af21 Revert "perf tools: event.h needs asm/perf_regs.h"
This reverts commit e083a21fca.

Not needed at all, tools/perf/util/perf_regs.h, included via:

  #include "perf_regs.h"

Should have a definition for PERF_REGS_MAX, and since this is dependent
on HAVE_PERF_REGS_SUPPORT, fixes the build on powerpc, noticed by trying
to cross compile this from ubuntu16.04 with a locally build libz &
elfutils pair, since those are not available in multilib packages.

Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-0bv204s71t4wuw1l53b6fz79@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-25 11:58:56 -03:00
Arnaldo Carvalho de Melo e5e6312b5b perf tests kmod-path: Fix build on ubuntu:16.04-x-armhf
Cross building it on Ubuntu 16.04 to ARM ends up showing we get
the free() prototype by luck in other environments, fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-0ktfgmmyhcfw8ondka2013f3@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-22 16:25:44 -03:00
Adrian Hunter 6c4d0b41ce perf tools: Add AVX-512 instructions to the new instructions test
Previous patches added support for Intel's AVX-512 instructions to the
kernel and perf tools instruction decoders.

AVX-512 instructions are documented in Intel Architecture Instruction
Set Extensions Programming Reference (February 2016).

Add a representative set of instructions to perf's "new instructions"
test. e.g.

	perf test "new instructions"

Or to view a particular instruction:

	perf test -v "new instructions" 2>&1 | grep vbroadcasti64x4

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: X86 ML <x86@kernel.org>
Link: http://lkml.kernel.org/r/1469003437-32706-5-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-21 09:37:26 -03:00
Adrian Hunter c61f4d5eba perf tools: Add AVX-512 support to the instruction decoder used by Intel PT
Add support for Intel's AVX-512 instructions to perf tools instruction
decoder used by Intel PT.  The kernel's instruction decoder was updated in
a previous patch.

AVX-512 instructions are documented in Intel Architecture Instruction Set
Extensions Programming Reference (February 2016).

AVX-512 instructions are identified by a EVEX prefix which, for the purpose
of instruction decoding, can be treated as though it were a 4-byte VEX
prefix.

Existing instructions which can now accept an EVEX prefix need not be
further annotated in the op code map (x86-opcode-map.txt). In the case of
new instructions, the op code map is updated accordingly.

Also add associated Mask Instructions that are used to manipulate mask
registers used in AVX-512 instructions.

A representative set of instructions is added to the perf tools new
instructions test in a subsequent patch.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: X86 ML <x86@kernel.org>
Link: http://lkml.kernel.org/r/1469003437-32706-4-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-21 09:37:18 -03:00
Adrian Hunter 6f6ef07f41 x86/insn: perf tools: Fix vcvtph2ps instruction decoding
vcvtph2ps does not have an immediate operand, so remove the erroneous
'Ib' from its opcode map entry. Add vcvtph2ps to the perf tools new
instructions test to verify it.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: X86 ML <x86@kernel.org>
Link: http://lkml.kernel.org/r/1469003437-32706-2-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-20 09:57:46 -03:00
Jiri Olsa 988dd774dc perf tests: Add is_printable_array test
Add automated test for is_printable_array function.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Pirko <jiri@mellanox.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1468685480-18951-4-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 19:50:35 -03:00
Jiri Olsa accaed2659 perf tools: Make is_printable_array global
It's used from 2 objects in perf, so it's better to keep just one copy.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Pirko <jiri@mellanox.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1468685480-18951-3-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 19:49:47 -03:00
Jiri Olsa 249de6e074 perf script python: Fix string vs byte array resolving
Jirka reported that python code returns all arrays as strings.  This
makes impossible to get all items for byte array tracepoint field
containing 0x00 value item.

Fixing this by scanning full length of the array and returning it as
PyByteArray object in case non printable byte is found.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Reported-and-Tested-by: Jiri Pirko <jiri@mellanox.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1468685480-18951-2-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 19:48:04 -03:00
Masami Hiramatsu e70493429b perf probe: Warn unmatched function filter correctly
Warn unmatched function filter correctly instead of warning
"symbol-loading error", since that can be a filter issue.

From the technical point of view, this adds a filter chech in map__load
and if there is a filter, it returns -2 (filter-out), instead of -1
(error), and perf-probe checks it and change message.

E.g. without this fix:

  # perf probe -F rt_sp*
  no symbols found in [kernel.kallsyms], maybe install a debug package?
  Failed to load symbols in kernel

With this fix:

  # perf probe -F rt_sp*
  no symbols passed the given filter.
  Failed to find symbols matched to "rt_sp*"
    Error: Failed to show functions.

Reported-and-Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/146885835596.16106.2293540792775552481.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 19:46:34 -03:00
Mark Rutland 9a6c582d57 perf cpu_map: Add more helpers
In some cases it's necessry to figure out the map-local index of a given
Linux logical CPU ID. Add a new helper, cpu_map__idx, to acquire this.
As the logic is largely the same as the existing cpu_map__has, this is
rewritten in terms of the new helper.

At the same time, add the inverse operation, cpu_map__cpu, which yields
the logical CPU id for a map-local index. While this can be performed
manually, wrapping this in a helper can make code more legible.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1468577293-19667-3-git-send-email-mark.rutland@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 19:42:47 -03:00
Mark Rutland 00e727bb38 perf stat: Balance opening and reading events
In create_perf_stat_counter, when a target CPU has not been provided, we
call __perf_evsel__open with empty_cpu_map, and open a single FD per
thread. However, in read_counter we assume that we opened events for the
product of threads and CPUs described in the evsel's cpu_map.

Thus, if an evsel has a cpu_map with more than one entry, we will
attempt to access FDs that we didn't open. This could result in a number
of problems (e.g. blocking while reading from STDIN if the fd memory
happened to be initialised to zero).

This is problematic for systems were a logical CPU PMU covers some
arbitrary subset of CPUs. The cpu_map of any evsel for that PMU will be
initialised based on the cpumask exposed through sysfs, even if the user
requests per-thread events.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1468577293-19667-2-git-send-email-mark.rutland@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 19:41:14 -03:00
Arnaldo Carvalho de Melo ae3c14a028 tools: Copy linux/{hash,poison}.h and check for drift
We were also using this directly from the kernel sources, the two last
cases, fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-7o14xvacqcjc5llc7gvjjyl8@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 18:41:50 -03:00
Arnaldo Carvalho de Melo 3aa0042769 perf tools: Remove include/linux/list.h from perf's MANIFEST
It hasn't been used since we made tools/ self sufficiente wrt list.h.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: d1b39d41eb ("tools: Make list.h self-sufficient")
Link: http://lkml.kernel.org/n/tip-w20ueqlf22kh7ctjqo0zjpig@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 18:35:11 -03:00
Arnaldo Carvalho de Melo de1e17b1d0 tools: Copy the bitops files accessed from the kernel and check for drift
copy some more kernel files accessed from tools/, check for drift.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-omz8xdyvvxgjiuqzwj6ecm6j@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 18:33:41 -03:00
Arnaldo Carvalho de Melo ad430729ae Remove: kernel unistd*h files from perf's MANIFEST, not used
No need to copy it to a detached tarball as they aren't used anymore

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-lopmaqi439ke10g1j9cxrxwt@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 18:14:44 -03:00
Arnaldo Carvalho de Melo e0643c4e9f perf tools: Remove tools/perf/util/include/linux/const.h
Not used anymore, remove one more file referencing kernel sources, i.e.
outside of tools/

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ykfjt3t8l0npxfwmekiwwyu6@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 17:53:22 -03:00
Arnaldo Carvalho de Melo 7e3f364113 perf tools: Remove tools/perf/util/include/asm/byteorder.h
Not used anymore. This also stops include linux/swab.h directly
from the kernel sources, remove that reference from the MANIFEST.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 17:52:42 -03:00
Arnaldo Carvalho de Melo 14f0652b4f perf tools: Add missing linux/compiler.h include to perf-sys.h
It uses the likely/unlikely macros, so need to include
<linux/compiler.h>.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-p0xrhgbkicsii9ohmhhprqpi@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 17:40:49 -03:00
Dan Carpenter 9fcfcdf3c7 perf jit: Remove some no-op error handling
The 'info.e_machine' struct member is an uint16_t so 'm' is never less
than zero.  It looks like this was maybe left over code from earlier
versions so I've just removed it.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: kernel-janitors@vger.kernel.org
Link: http://lkml.kernel.org/r/20160715210836.GB19522@mwanda
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 12:20:00 -03:00
Dan Carpenter e03141db36 perf jit: Add missing curly braces
It doesn't change the runtime behavior, but my static checker complains
that curly braces were intended.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: kernel-janitors@vger.kernel.org
Link: http://lkml.kernel.org/r/20160715210712.GA19522@mwanda
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-18 12:20:00 -03:00
Wang Nan 4ea648aec0 perf record: Add --tail-synthesize option
When working with overwritable ring buffer there's a inconvenience
problem: if perf dumps data after a long period after it starts,
non-sample events may lost, which makes following 'perf report' unable
to identify proc name and mmap layout. For example:

 # perf record -m 4 -e raw_syscalls:* -g --overwrite --switch-output \
        dd if=/dev/zero of=/dev/null

send SIGUSR2 after dd runs long enough. The resuling perf.data lost
correct comm and mmap events:

 # perf script -i perf.data.2016061522374354
 perf 24478 [004] 2581325.601789:  raw_syscalls:sys_exit: NR 0 = 512
 ^^^^
 Should be 'dd'
                   27b2e8 syscall_slow_exit_work+0xfe2000e3 (/lib/modules/4.6.0-rc3+/build/vmlinux)
                   203cc7 do_syscall_64+0xfe200117 (/lib/modules/4.6.0-rc3+/build/vmlinux)
                   b18d83 return_from_SYSCALL_64+0xfe200000 (/lib/modules/4.6.0-rc3+/build/vmlinux)
             7f47c417edf0 [unknown] ([unknown])
             ^^^^^^^^^^^^
             Fail to unwind

This patch provides a '--tail-synthesize' option, allows perf to collect
system status when finalizing output file. In resuling output file, the
non-sample events reflect system status when dumping data.

After this patch:
 # perf record -m 4 -e raw_syscalls:* -g --overwrite --switch-output --tail-synthesize \
        dd if=/dev/zero of=/dev/null

 # perf script -i perf.data.2016061600544998
 dd 27364 [004] 2583244.994464: raw_syscalls:sys_enter: NR 1 (1, ...
 ^^
 Correct comm
                   203a18 syscall_trace_enter_phase2+0xfe2001a8 ([kernel.kallsyms])
                   203aa5 syscall_trace_enter+0xfe200055 ([kernel.kallsyms])
                   203caa do_syscall_64+0xfe2000fa ([kernel.kallsyms])
                   b18d83 return_from_SYSCALL_64+0xfe200000 ([kernel.kallsyms])
                    d8e50 __GI___libc_write+0xffff01d9639f4010 (/tmp/oxygen_root-w00229757/lib64/libc-2.18.so)
                    ^^^^^
                    Correct unwind

This option doesn't aim to solve this problem completely. If a process
terminates before SIGUSR2, we still lost its COMM and MMAP events. For
example, we can't unwind correctly from the final perf.data we get from
the previous example, because when perf collects the final output file
(when we press C-c), 'dd' has been terminated so its '/proc/<pid>/mmap'
becomes empty.

However, this is a cheaper choice. To completely solve this problem we
need to continously output non-sample events. To satisify the
requirement of daemonization, we need to merge them periodically. It is
possible but requires much more code and cycles.

Automatically select --tail-synthesize when --overwrite is provided.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1468485287-33422-16-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-15 17:27:52 -03:00