We copy headers from include/, arch/ to allow tools/ use defines,
structs from newer kernels and still be able to build on older systems.
We then, as part of a build, check if those copies got out of sync, when
we emit a warning, so that we can check if something needs to be
reflected on the tools, e.g. a 'perf trace' syscall argument beautifier
needs tweaking.
But we don't have to be super strict with that, for instance, extra
spaces, tabs or blank lines aren't problematic, so change
check-headers.sh to have "--ignore-blank-lines --ignore-space-change" as
default "diff" arguments.
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-d8emqpdc3m2qtzt1ei8ra2tf@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
So that we can build on older systems where otherwise we would end up
with:
CC /tmp/build/perf/trace/beauty/ioctl.o
trace/beauty/ioctl.c: In function 'ioctl__scnprintf_tty_cmd':
trace/beauty/ioctl.c:25:17: error: 'TIOCGEXCL' undeclared (first use in this function)
trace/beauty/ioctl.c:25:17: note: each undeclared identifier is reported only once for each function it appears in
trace/beauty/ioctl.c:25:2: error: array index in initializer not of integer type
trace/beauty/ioctl.c:25:2: error: (near initialization for 'ioctl_tty_cmd')
This way we can build a tool on an older system and it will still be
capable of processing perf.data files generated on newer systems.
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-8qvkv6txwuzua6d0yvt65wl3@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull perf/core improvements and fixes for 4.14 from Arnaldo Carvalho de Melo:
New features:
- Add PERF_SAMPLE_CALLCHAIN and PERF_RECORD_MMAP[2] to 'perf data' CTF
conversion, allowing CTF trace visualization tools to show callchains
and to resolve symbols (Geneviève Bastien)
Improvements:
- Use group read for event groups in 'perf stat', reducing overhead when
groups are defined in the event specification, i.e. when using {} to
enclose a list of events, asking them to be read at the same time,
e.g.: "perf stat -e '{cycles,instructions}'" (Jiri Olsa)
Fixes:
- Do not overwrite perf_sample->weight in 'perf annotate' when
processing samples, use whatever came from the kernel when
perf_event_attr.sample_type has PERF_SAMPLE_WEIGHT set or just handle
its default value, 0, when that is not set and "weight" is one of the
sort orders chosen (Arnaldo Carvalho de Melo)
- 'perf annotate --show-total-period' fixes:
- TUI should show period, not nr_samples
- Set appropriate column width for period/percent
- Fix the column header to show "Period" when when that is what
is being asked for
(Taeung Song, Arnaldo Carvalho de Melo)
- Use default sort if evlist is empty, fixing pipe mode (David Carrillo-Cisneros)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This adds the mmap and mmap2 events to the CTF trace obtained from perf
data.
These events will allow CTF trace visualization tools like Trace Compass
to automatically resolve the symbols of the callchain to the
corresponding function or origin library.
To include those events, one needs to convert with the --all option.
Here follows an output of babeltrace:
$ sudo perf data convert --all --to-ctf myctftrace
$ babeltrace ./myctftrace
[19:00:00.000000000] (+0.000000000) perf_mmap2: { cpu_id = 0 },
{ pid = 638, tid = 638, start = 0x7F54AE39E000, filename =
"/usr/lib/ld-2.25.so" }
[19:00:00.000000000] (+0.000000000) perf_mmap2: { cpu_id = 0 }, { pid =
638, tid = 638, start = 0x7F54AE565000, filename =
"/usr/lib/libudev.so.1.6.6" }
[19:00:00.000000000] (+0.000000000) perf_mmap2: { cpu_id = 0 }, { pid =
638, tid = 638, start = 0x7FFC093EA000, filename = "[vdso]" }
Signed-off-by: Geneviève Bastien <gbastien@versatic.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Francis Deslauriers <francis.deslauriers@efficios.com>
Cc: Julien Desfossez <jdesfossez@efficios.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170727181205.24843-2-gbastien@versatic.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
In commit f8f4aaead5 ("perf annotate: Finally display IPC and cycle
accounting") the 'pcnt_width' variable was abused in a few places to
also include the optional width of the "IPC" and "cycles" columns, while
in other places we stopped using 'pcnt_width' and instead its previous
equation...
Now that we need to tap into annotate_browser__pcnt_width() to consider
if --show-total-period is being used and instead of that hardcoded 7
(strlen("Percent")) we need to use it or strlen("Event count") we need
this properly clarified to avoid having to touch all the (7 * nr_events)
places.
Clarify this by introducing a separate annotate_browser__cycles_width()
to leave the pcnt_width calculate just what its name implies.
Cc: Taeung Song <treeze.taeung@gmail.com>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-szgb07t4k5wtvks8nzwkg710@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Fixes bug noted by Jiri in https://lkml.org/lkml/2017/6/13/755 and
caused by commit d49dadea78 ("perf tools: Make 'trace' or
'trace_fields' sort key default for tracepoint events") not taking into
account that evlist is empty in pipe-mode.
Before this commit, pipe mode will only show bogus "100.00% N/A"
instead of correct output as follows:
$ perf record -o - sleep 1 | perf report -i -
# To display the perf.data header info, please use --header/--header-only options.
#
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.000 MB - ]
#
# Total Lost Samples: 0
#
# Samples: 8 of event 'cycles:ppH'
# Event count (approx.): 145658
#
# Overhead Trace output
# ........ ............
#
100.00% N/A
Correct output, after patch:
$ perf record -o - sleep 1 | perf report -i -
# To display the perf.data header info, please use --header/--header-only options.
#
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.000 MB - ]
#
# Total Lost Samples: 0
#
# Samples: 8 of event 'cycles:ppH'
# Event count (approx.): 191331
#
# Overhead Command Shared Object Symbol
# ........ ....... ................. .................................
#
81.63% sleep libc-2.19.so [.] _exit
13.58% sleep ld-2.19.so [.] do_lookup_x
2.34% sleep [kernel.kallsyms] [k] context_switch
2.34% sleep libc-2.19.so [.] __GI___libc_nanosleep
0.11% perf [kernel.kallsyms] [k] __intel_pmu_enable_a
Reported-by: Jiri Olsa <jolsa@kernel.org>
Report-Link: https://lkml.kernel.org/r/20170613185422.GA6092@krava
Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Turner <pjt@google.com>
Cc: Simon Que <sque@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: d49dadea78 ("perf tools: Make 'trace' or 'trace_fields' sort key default for tracepoint events")
Link: https://lkml.kernel.org/r/20170721051157.47331-1-davidcc@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Make perf stat use group read if there are groups defined. The group
read will get the values for all member of groups within a single
syscall instead of calling read syscall for every event.
We can see considerable less amount of kernel cycles spent on single
group read, than reading each event separately, like for following perf
stat command:
# perf stat -e {cycles,instructions} -I 10 -a sleep 1
Monitored with "perf stat -r 5 -e '{cycles:u,cycles:k}'"
Before:
24,325,676 cycles:u
297,040,775 cycles:k
1.038554134 seconds time elapsed
After:
25,034,418 cycles:u
158,256,395 cycles:k
1.036864497 seconds time elapsed
The perf_evsel__open fallback changes contributed by Andi Kleen.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20170726120206.9099-4-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This file was copied from the kernel so that we could build tools/perf/
on older systems where some newer defines, such as these are available:
CC trace/beauty/fcntl.o
trace/beauty/fcntl.c: In function ‘syscall_arg__scnprintf_fcntl_arg’:
trace/beauty/fcntl.c:93:13: error: ‘F_OFD_SETLK’ undeclared (first use in this function)
cmd == F_OFD_SETLK || cmd == F_OFD_SETLKW || cmd == F_OFD_GETLK ||
^
trace/beauty/fcntl.c:93:13: note: each undeclared identifier is reported only once for each function it appears in
trace/beauty/fcntl.c:93:35: error: ‘F_OFD_SETLKW’ undeclared (first use in this function)
cmd == F_OFD_SETLK || cmd == F_OFD_SETLKW || cmd == F_OFD_GETLK ||
^
trace/beauty/fcntl.c:93:58: error: ‘F_OFD_GETLK’ undeclared (first use in this function)
cmd == F_OFD_SETLK || cmd == F_OFD_SETLKW || cmd == F_OFD_GETLK ||
^
mv: cannot stat ‘trace/beauty/.fcntl.o.tmp’: No such file or directory
make[4]: *** [trace/beauty/fcntl.o] Error 1
make[3]: *** [trace/beauty] Error 2
make[3]: *** Waiting for unfinished jobs....
CC tests/llvm.o
But we need to make sure that it is also in the tools/perf/MANIFEST file, that
is used to build a tarball for detached (from the kernel sources) compilation,
which was failing, with the above message, on a RHEL7.4 system, 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>
Fixes: 84d1d8a12d ("tools include uapi asm-generic: Grab a copy of fcntl.h")
Link: http://lkml.kernel.org/n/tip-2d5px7aq5stbwi24pgirwtlm@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Today, when a JSON file fails parsing the build continues, but there are
no json files built in, which is difficult to debug later. Make the
build stop on a parse error instead.
v2: Add fixes from Sukadev. Now we handle architectures
with no JSON events correctly. And fix some stale comments.
Committer note:
Tested by running the cross build container tests, that were all failing
for v1.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20170725001638.19990-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Current --branch-history LBR annotation displays confused data. For
example, each cycles report is duplicated on both "from" and "to"
entries.
For example:
perf report --branch-history --no-children --stdio
--2.32%--main div.c:39 (COND_BWD CROSS_2M predicted:49.7% cycles:1)
main div.c:44 (predicted:49.7% cycles:1)
main div.c:42 (RET CROSS_2M cycles:2)
compute_flag div.c:28 (cycles:2)
compute_flag div.c:27 (RET CROSS_2M cycles:1)
rand rand.c:28 (cycles:1)
rand rand.c:28 (RET CROSS_2M cycles:1)
__random random.c:298 (cycles:1)
__random random.c:297 (COND_BWD CROSS_2M cycles:1)
__random random.c:295 (cycles:1)
__random random.c:295 (COND_BWD CROSS_2M cycles:1)
__random random.c:295 (cycles:1)
__random random.c:295 (RET CROSS_2M cycles:9)
The cycles should be tagged only on the "from". It's for the code block
that ends with "from", not for "to".
Another issue is the "predicted:49.7%" is duplicated too (tag on both
"from" and "to").
This patch tags the branch type/flag on "to" and tag the cycles on
"from".
For example:
--2.32%--main div.c:39 (COND_BWD CROSS_2M predicted:49.7%)
main div.c:44 (cycles:1)
main div.c:42 (RET CROSS_2M)
compute_flag div.c:28 (cycles:2)
compute_flag div.c:27 (RET CROSS_2M)
rand rand.c:28 (cycles:1)
rand rand.c:28 (RET CROSS_2M)
__random random.c:298 (cycles:1)
__random random.c:297 (COND_BWD CROSS_2M)
__random random.c:295 (cycles:1)
__random random.c:295 (COND_BWD CROSS_2M)
__random random.c:295 (cycles:1)
__random random.c:295 (RET CROSS_2M)
|
--2.23%--__random_r random_r.c:392 (cycles:9)
In this example, The "main div.c:39 (COND_BWD CROSS_2M predicted:49.7%)"
is "to" of branch and "main div.c:44 (cycles:1)" is "from" of branch.
It should be easier for understanding than before.
Signed-off-by: Yao Jin <yao.jin@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1500894547-18411-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
perf record -b -g <command>
perf report --branch-history
This merges the LBRs with the callgraphs.
However it would be nice if it also works without callgraphs (-g) set in
perf record, so that only the LBRs are displayed. But currently perf
report errors in this case. For example,
perf record -b <command>
perf report --branch-history
Error:
Selected -g or --branch-history but no callchain data. Did
you call 'perf record' without -g?
This patch displays the LBRs only even if callgraphs(-g) is not enabled
in perf record.
Change log:
v2: According to Milian Wolff's comment, change the obsolete error
message. Now the error message is:
┌─Error:─────────────────────────────────────┐
│Selected -g or --branch-history. │
│But no callchain or branch data. │
│Did you call 'perf record' without -g or -b?│
│ │
│ │
│Press any key... │
└────────────────────────────────────────────┘
When passing the last parameter to hists__fprintf,
changes "|" to "||".
hists__fprintf(hists, !quiet, 0, 0, rep->min_percent, stdout,
symbol_conf.use_callchain || symbol_conf.show_branchflag_count);
Signed-off-by: Yao Jin <yao.jin@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1494240182-28899-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When converting from atomic_t to refcount_t we didn't follow the usual
step of initializing it to one before taking any new reference, which
trips over checking if taking a reference for a freed refcount_t, fix
it.
Brendan's report:
---
It's 4.12-rc7, with node v4.4.1. I'm building 4.13-rc1 now, as I hit
what I think is another unrelated perf bug and I'm starting to wonder
what else is broken on that version:
(root) /mnt/src/linux-4.12-rc7/tools/perf # ./perf record -F 99 -a -e
cpu-clock --cgroup=docker/f9e9d5df065b14646e8a11edc837a13877fd90c171137b2ba3feb67a0201cb65
-g
perf: /mnt/src/linux-4.12-rc7/tools/include/linux/refcount.h:108:
refcount_inc: Assertion `!(!refcount_inc_not_zero(r))' failed.
Aborted
that used to work...
---
Testing it:
Before:
# perf stat -e cycles -C 0 --cgroup /
perf: /home/acme/git/linux/tools/include/linux/refcount.h:108: refcount_inc: Assertion `!(!refcount_inc_not_zero(r))' failed.
Aborted (core dumped)
#
After:
# perf stat -e cycles -C 0 --cgroup /
^C
Performance counter stats for 'CPU(s) 0':
132,081,393 cycles /
2.492942763 seconds time elapsed
#
Reported-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Acked-by: Elena Reshetova <elena.reshetova@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: David Carrillo-Cisneros <davidcc@google.com>
Cc: Kees Kook <keescook@chromium.org>
Cc: Krister Johansen <kjlx@templeofstupid.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sudeep Holla <Sudeep.Holla@arm.com>
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 79c5fe6db8 ("perf cgroup: Convert cgroup_sel.refcnt from atomic_t to refcount_t")
Link: http://lkml.kernel.org/n/tip-l7ovfblq14ip2i08m1g0fkhv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
On s390x the kernel text segment starts at address 0x0. When perf
report reads kernel symbols from vmlinux file it adds an offset of
0x1000.
For example see symbol set_reset_devices:
[root@s8360047 linux-devel]# nm -A vmlinux| fgrep set_reset_devices
vmlinux:0000000001379000 t set_reset_devices
[root@s8360047 linux-devel]#
[root@s8360047 linux-devel]# fgrep set_reset_devices /proc/kallsyms
0000000001379000 t set_reset_devices
[root@s8360047 linux-devel]#
The kernel symbol table and the vmlinux file have the same address for
symbol set_reset_devices namely 1379000.
When perf report reads this symbols it displays it with address
symbol__new: set_reset_devices 0x137a000-0x137a018
There is a difference between perf report and vmlinux of 0x1000.
The reason for the difference is at kernel symbol load time in function
dso__load_sym(). The vmlinux file is investigated with its ELF header.
Command readelf shows this:
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .text PROGBITS 0000000000000000 00001000
0000000000b0e0c2 0000000000000000 AX 0 0 128
This leads to an invalid calculation of the symbol start address, see
file utit/symbol-elf.c line 974:
/* Adjust symbol to map to file offset */
if (adjust_kernel_syms)
sym.st_value -= shdr.sh_addr - shdr.sh_offset;
With shdr.sh_addr set to 0x0 and shdr.sh_offset set to 0x1000 as read
from the ELF .text section 0x1000 is added to the symbol address.
I would like to fix this by introducing an archticture specific function
named elf__needs_adjust_symbols(). This is the same approach as done by
PowerPC. The function currently does not exist for s390x and the
default weak one is used. The s390x specific one returns false when
symsrc_init() is invoked for kernel symbols and results in variable
adjust_kernel_syms being false. This omits the adjustment and the
correct address is displayed (when symbol resolvement does not work).
The s390x specific function returns false for kernel symbol adjustment
and returns true for kernel modules, processes and shared libraries.
Signed-off-by: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
LPU-Reference: 20170713130252.6167-1-tmricht@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull perf fixes from Ingo Molnar:
"Two hw-enablement patches, two race fixes, three fixes for regressions
of semantics, plus a number of tooling fixes"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel: Add proper condition to run sched_task callbacks
perf/core: Fix locking for children siblings group read
perf/core: Fix scheduling regression of pinned groups
perf/x86/intel: Fix debug_store reset field for freq events
perf/x86/intel: Add Goldmont Plus CPU PMU support
perf/x86/intel: Enable C-state residency events for Apollo Lake
perf symbols: Accept zero as the kernel base address
Revert "perf/core: Drop kernel samples even though :u is specified"
perf annotate: Fix broken arrow at row 0 connecting jmp instruction to its target
perf evsel: State in the default event name if attr.exclude_kernel is set
perf evsel: Fix attr.exclude_kernel setting for default cycles:p
To make it more clear that it is the sum of all the nr_samples fields in the
addr[] entries, i.e.:
sym_hist->nr_samples = sum(sym_hist->addr[0 .. symbol__size(sym)]->nr_samples)
Committer notes:
Taeung had renamed it to total_samples, but using nr_samples, as in the
added explanation above, looks clearer and establishes the direct
connection, making clear it is about the _number_ of samples.
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1500500211-16599-1-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
struct sym_hist has addr[] but it should have not only number of samples
but also the sample period. So use new struct symhist_entry to pave the
way to have that.
Committer notes:
This initial patch will only introduce the struct sym_hist_entry and use
only the nr_samples member, which makes the code clearer and paves the
way to save the period as well.
Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1500500205-16553-1-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Avoiding a loop, so now its quite convenient to ssh to a machine and
then simply do:
# perf trace
To trace all syscalls without causing a loop.
This was possible using --filter-pids, i.e. once you noticed the loop,
get the sshd pid and add it to --filter-pids, restarting the 'perf
trace'.
Now to figure out how to do that in a X terminal, the other common
scenario, which is way more involved, as there are multiple processes
communicating to process terminal activity...
Using --filter-pids + '-e \!syscall,names,you,dont,need' may be a good
approximation when having to do syswide tracing on your workstation.
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-68rjeao9wnpylla41htk7xps@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
