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authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-20 10:29:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-20 10:29:15 -0700
commit9c2b957db1772ebf942ae7a9346b14eba6c8ca66 (patch)
tree0dbb83e57260ea7fc0dc421f214d5f1b26262005 /tools/perf/Documentation/perf-record.txt
parent0bbfcaff9b2a69c71a95e6902253487ab30cb498 (diff)
parentbea95c152dee1791dd02cbc708afbb115bb00f9a (diff)
Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf events changes for v3.4 from Ingo Molnar: - New "hardware based branch profiling" feature both on the kernel and the tooling side, on CPUs that support it. (modern x86 Intel CPUs with the 'LBR' hardware feature currently.) This new feature is basically a sophisticated 'magnifying glass' for branch execution - something that is pretty difficult to extract from regular, function histogram centric profiles. The simplest mode is activated via 'perf record -b', and the result looks like this in perf report: $ perf record -b any_call,u -e cycles:u branchy $ perf report -b --sort=symbol 52.34% [.] main [.] f1 24.04% [.] f1 [.] f3 23.60% [.] f1 [.] f2 0.01% [k] _IO_new_file_xsputn [k] _IO_file_overflow 0.01% [k] _IO_vfprintf_internal [k] _IO_new_file_xsputn 0.01% [k] _IO_vfprintf_internal [k] strchrnul 0.01% [k] __printf [k] _IO_vfprintf_internal 0.01% [k] main [k] __printf This output shows from/to branch columns and shows the highest percentage (from,to) jump combinations - i.e. the most likely taken branches in the system. "branches" can also include function calls and any other synchronous and asynchronous transitions of the instruction pointer that are not 'next instruction' - such as system calls, traps, interrupts, etc. This feature comes with (hopefully intuitive) flat ascii and TUI support in perf report. - Various 'perf annotate' visual improvements for us assembly junkies. It will now recognize function calls in the TUI and by hitting enter you can follow the call (recursively) and back, amongst other improvements. - Multiple threads/processes recording support in perf record, perf stat, perf top - which is activated via a comma-list of PIDs: perf top -p 21483,21485 perf stat -p 21483,21485 -ddd perf record -p 21483,21485 - Support for per UID views, via the --uid paramter to perf top, perf report, etc. For example 'perf top --uid mingo' will only show the tasks that I am running, excluding other users, root, etc. - Jump label restructurings and improvements - this includes the factoring out of the (hopefully much clearer) include/linux/static_key.h generic facility: struct static_key key = STATIC_KEY_INIT_FALSE; ... if (static_key_false(&key)) do unlikely code else do likely code ... static_key_slow_inc(); ... static_key_slow_inc(); ... The static_key_false() branch will be generated into the code with as little impact to the likely code path as possible. the static_key_slow_*() APIs flip the branch via live kernel code patching. This facility can now be used more widely within the kernel to micro-optimize hot branches whose likelihood matches the static-key usage and fast/slow cost patterns. - SW function tracer improvements: perf support and filtering support. - Various hardenings of the perf.data ABI, to make older perf.data's smoother on newer tool versions, to make new features integrate more smoothly, to support cross-endian recording/analyzing workflows better, etc. - Restructuring of the kprobes code, the splitting out of 'optprobes', and a corner case bugfix. - Allow the tracing of kernel console output (printk). - Improvements/fixes to user-space RDPMC support, allowing user-space self-profiling code to extract PMU counts without performing any system calls, while playing nice with the kernel side. - 'perf bench' improvements - ... and lots of internal restructurings, cleanups and fixes that made these features possible. And, as usual this list is incomplete as there were also lots of other improvements * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (120 commits) perf report: Fix annotate double quit issue in branch view mode perf report: Remove duplicate annotate choice in branch view mode perf/x86: Prettify pmu config literals perf report: Enable TUI in branch view mode perf report: Auto-detect branch stack sampling mode perf record: Add HEADER_BRANCH_STACK tag perf record: Provide default branch stack sampling mode option perf tools: Make perf able to read files from older ABIs perf tools: Fix ABI compatibility bug in print_event_desc() perf tools: Enable reading of perf.data files from different ABI rev perf: Add ABI reference sizes perf report: Add support for taken branch sampling perf record: Add support for sampling taken branch perf tools: Add code to support PERF_SAMPLE_BRANCH_STACK x86/kprobes: Split out optprobe related code to kprobes-opt.c x86/kprobes: Fix a bug which can modify kernel code permanently x86/kprobes: Fix instruction recovery on optimized path perf: Add callback to flush branch_stack on context switch perf: Disable PERF_SAMPLE_BRANCH_* when not supported perf/x86: Add LBR software filter support for Intel CPUs ...
Diffstat (limited to 'tools/perf/Documentation/perf-record.txt')
-rw-r--r--tools/perf/Documentation/perf-record.txt38
1 files changed, 36 insertions, 2 deletions
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 2937f7e14bb7..a1386b2fff00 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -52,11 +52,15 @@ OPTIONS
-p::
--pid=::
- Record events on existing process ID.
+ Record events on existing process ID (comma separated list).
-t::
--tid=::
- Record events on existing thread ID.
+ Record events on existing thread ID (comma separated list).
+
+-u::
+--uid=::
+ Record events in threads owned by uid. Name or number.
-r::
--realtime=::
@@ -148,6 +152,36 @@ an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must ha
corresponding events, i.e., they always refer to events defined earlier on the command
line.
+-b::
+--branch-any::
+Enable taken branch stack sampling. Any type of taken branch may be sampled.
+This is a shortcut for --branch-filter any. See --branch-filter for more infos.
+
+-j::
+--branch-filter::
+Enable taken branch stack sampling. Each sample captures a series of consecutive
+taken branches. The number of branches captured with each sample depends on the
+underlying hardware, the type of branches of interest, and the executed code.
+It is possible to select the types of branches captured by enabling filters. The
+following filters are defined:
+
+ - any: any type of branches
+ - any_call: any function call or system call
+ - any_ret: any function return or system call return
+ - any_ind: any indirect branch
+ - u: only when the branch target is at the user level
+ - k: only when the branch target is in the kernel
+ - hv: only when the target is at the hypervisor level
+
++
+The option requires at least one branch type among any, any_call, any_ret, ind_call.
+The privilege levels may be ommitted, in which case, the privilege levels of the associated
+event are applied to the branch filter. Both kernel (k) and hypervisor (hv) privilege
+levels are subject to permissions. When sampling on multiple events, branch stack sampling
+is enabled for all the sampling events. The sampled branch type is the same for all events.
+The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k
+Note that this feature may not be available on all processors.
+
SEE ALSO
--------
linkperf:perf-stat[1], linkperf:perf-list[1]