tjh.dev
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
Linux kernel mirror (for testing)
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Sync the following tooling headers with the latest kernel version:
tools/arch/powerpc/include/uapi/asm/kvm.h
tools/arch/x86/include/asm/cpufeatures.h
tools/include/uapi/drm/i915_drm.h
tools/include/uapi/linux/if_link.h
tools/include/uapi/linux/kvm.h
All the changes are new ABI additions which don't impact their use
in existing tooling.
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On Intel test case trace+probe_libc_inet_pton.sh succeeds and the
output is:
[root@f27 perf]# ./perf trace --no-syscalls
-e probe_libc:inet_pton/max-stack=3/ ping -6 -c 1 ::1
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.037 ms
--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.037/0.037/0.037/0.000 ms
0.000 probe_libc:inet_pton:(7fa40ac618a0))
__GI___inet_pton (/usr/lib64/libc-2.26.so)
getaddrinfo (/usr/lib64/libc-2.26.so)
main (/usr/bin/ping)
The kernel stack unwinder is used, it is specified implicitly
as call-graph=fp (frame pointer).
On s390x only dwarf is available for stack unwinding. It is also
done in user space. This requires different parameter setup
and result checking for s390x and Intel.
This patch adds separate perf trace setup and result checking
for Intel and s390x. On s390x specify this command line to
get a call-graph and handle the different call graph result
checking:
[root@s35lp76 perf]# ./perf trace --no-syscalls
-e probe_libc:inet_pton/call-graph=dwarf/ ping -6 -c 1 ::1
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.041 ms
--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.041/0.041/0.041/0.000 ms
0.000 probe_libc:inet_pton:(3ffb9942060))
__GI___inet_pton (/usr/lib64/libc-2.26.so)
gaih_inet (inlined)
__GI_getaddrinfo (inlined)
main (/usr/bin/ping)
__libc_start_main (/usr/lib64/libc-2.26.so)
_start (/usr/bin/ping)
[root@s35lp76 perf]#
Before:
[root@s8360047 perf]# ./perf test -vv 58
58: probe libc's inet_pton & backtrace it with ping :
--- start ---
test child forked, pid 26349
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.079 ms
--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.079/0.079/0.079/0.000 ms
0.000 probe_libc:inet_pton:(3ff925c2060))
test child finished with -1
---- end ----
probe libc's inet_pton & backtrace it with ping: FAILED!
[root@s8360047 perf]#
After:
[root@s35lp76 perf]# ./perf test -vv 57
57: probe libc's inet_pton & backtrace it with ping :
--- start ---
test child forked, pid 38708
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.038 ms
--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.038/0.038/0.038/0.000 ms
0.000 probe_libc:inet_pton:(3ff87342060))
__GI___inet_pton (/usr/lib64/libc-2.26.so)
gaih_inet (inlined)
__GI_getaddrinfo (inlined)
main (/usr/bin/ping)
__libc_start_main (/usr/lib64/libc-2.26.so)
_start (/usr/bin/ping)
test child finished with 0
---- end ----
probe libc's inet_pton & backtrace it with ping: Ok
[root@s35lp76 perf]#
On Intel the test case runs unchanged and succeeds.
Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180117083831.101001-1-tmricht@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add the --force option to the man page.
Signed-off-by: Sangwon Hong <qpakzk@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Taeung Song <treeze.taeung@gmail.com>
Link: http://lkml.kernel.org/r/1517831315-31490-1-git-send-email-qpakzk@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Instead of home grown function let's use what library provides us.
Signed-off-by: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20180129130359.1490-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The latency of perf_top__mmap_read() should be lower than refresh time.
If not, give some hints to reduce the latency.
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-18-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
perf_top__mmap_read() has a severe performance issue in the Knights
Landing/Mill platform, when monitoring heavy load systems. It costs
several minutes to finish, which is unacceptable.
Currently, 'perf top' uses the non overwrite mode. For non overwrite
mode, it tries to read everything in the ringbuffer and doesn't pause
it. Once there are lots of samples delivered persistently, the
processing time could be very long. Also, the latest samples could be
lost when the ringbuffer is full.
For overwrite mode, it takes a snapshot for the system by pausing the
ringbuffer, which could significantly reduce the processing time. Also,
the overwrite mode always keep the latest samples. Considering the real
time requirement for 'perf top', the overwrite mode is more suitable for
it.
Actually, 'perf top' was overwrite mode. It is changed to non overwrite
mode since commit 93fc64f14472 ("perf top: Switch to non overwrite
mode"). It's better to change it back to overwrite mode by default.
For the kernel which doesn't support overwrite mode, it will fall back
to non overwrite mode.
There would be some records lost in overwrite mode because of pausing
the ringbuffer. It has little impact for the accuracy of the snapshot
and can be tolerated.
For overwrite mode, unconditionally wait 100 ms before each snapshot. It
also reduces the overhead caused by pausing ringbuffer, especially on
light load system.
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-17-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
There would be some records lost in overwrite mode because of pausing
the ringbuffer. It has little impact for the accuracy of the snapshot
and could be tolerated by 'perf top'.
Remove the lost events checking.
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-16-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
For overwrite mode, the ringbuffer will be paused. The event lost is
expected. It needs a way to notify the browser not print the warning.
It will be used later for perf top to disable lost event warning in
overwrite mode. There is no behavior change for now.
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-15-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Switch to non-overwrite mode if kernel doesnot support overwrite
ringbuffer.
It's only effect when overwrite mode is supported. No change to current
behavior.
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-14-git-send-email-kan.liang@intel.com
[ Use perf_missing_features.write_backward instead of the non merged is_write_backward_fail() ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
As tools may need to adjust to missing features, as 'perf top' will, in
the next csets, to cope with a missing 'write_backward' feature.
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-jelngl9q1ooaizvkcput9tic@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Per-event overwrite term is not forbidden in 'perf top', which can bring
problems. Because 'perf top' only support non-overwrite mode now.
Add new rules and check regarding to overwrite term for 'perf top'.
- All events either have same per-event term or don't have per-event
mode setting. Otherwise, it will error out.
- Per-event overwrite term should be consistent as opts->overwrite.
If not, updating the opts->overwrite according to per-event term.
Make it possible to support either non-overwrite or overwrite mode.
The overwrite mode is forbidden now, which will be removed when the
overwrite mode is supported later.
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-12-git-send-email-kan.liang@intel.com
[ Renamed perf_top_overwrite_check to perf_top__overwrite_check, to follow existing convention ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Discards perf_mmap__read_backward() and perf_mmap__read_catchup(). No
tools use them.
There are tools still use perf_mmap__read_forward(). Keep it, but add
comments to point to the new interface for future use.
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-11-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Use the new perf_mmap__read_* interfaces for overwrite ringbuffer test.
Commiter notes:
Testing:
[root@seventh ~]# perf test -v backward
48: Read backward ring buffer :
--- start ---
test child forked, pid 8309
Using CPUID GenuineIntel-6-9E
mmap size 1052672B
mmap size 8192B
Finished reading overwrite ring buffer: rewind
test child finished with 0
---- end ----
Read backward ring buffer: Ok
[root@seventh ~]#
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-10-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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