kernel/linux.git/tools/perf/util/thread.h, branch v6.1.168

perf tools: Add guest_cpu to hypervisor threads

2022-07-20T14:08:04+00:00

It is possible to know which guest machine was running at a point in time based on the PID of the currently running host thread. That is, perf identifies guest machines by the PID of the hypervisor. To determine the guest CPU, put it on the hypervisor (QEMU) thread for that VCPU. This is done when processing the id_index which provides the necessary information. Signed-off-by: Adrian Hunter Cc: Andi Kleen Cc: Ian Rogers Cc: Jiri Olsa Cc: Namhyung Kim Cc: kvm@vger.kernel.org Link: https://lore.kernel.org/r/20220711093218.10967-13-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf callchain: Stitch LBR call stack

2020-04-18T12:05:01+00:00

In LBR call stack mode, the depth of reconstructed LBR call stack limits to the number of LBR registers. For example, on skylake, the depth of reconstructed LBR call stack is always <= 32. # To display the perf.data header info, please use # --header/--header-only options. # # # Total Lost Samples: 0 # # Samples: 6K of event 'cycles' # Event count (approx.): 6487119731 # # Children Self Command Shared Object Symbol # ........ ........ ............... .................. # ................................ 99.97% 99.97% tchain_edit tchain_edit [.] f43 | --99.64%--f11 f12 f13 f14 f15 f16 f17 f18 f19 f20 f21 f22 f23 f24 f25 f26 f27 f28 f29 f30 f31 f32 f33 f34 f35 f36 f37 f38 f39 f40 f41 f42 f43 For a call stack which is deeper than LBR limit, HW will overwrite the LBR register with oldest branch. Only partial call stacks can be reconstructed. However, the overwritten LBRs may still be retrieved from previous sample. At that moment, HW hasn't overwritten the LBR registers yet. Perf tools can stitch those overwritten LBRs on current call stacks to get a more complete call stack. To determine if LBRs can be stitched, perf tools need to compare current sample with previous sample. - They should have identical LBR records (Same from, to and flags values, and the same physical index of LBR registers). - The searching starts from the base-of-stack of current sample. Once perf determines to stitch the previous LBRs, the corresponding LBR cursor nodes will be copied to 'lists'. The 'lists' is to track the LBR cursor nodes which are going to be stitched. When the stitching is over, the nodes will not be freed immediately. They will be moved to 'free_lists'. Next stitching may reuse the space. Both 'lists' and 'free_lists' will be freed when all samples are processed. Committer notes: Fix the intel-pt.c initialization of the union with 'struct branch_flags', that breaks the build with its unnamed union on older gcc versions. Uninline thread__free_stitch_list(), as it grew big and started dragging includes to thread.h, so move it to thread.c where what it needs in terms of headers are already there. This fixes the build in several systems such as debian:experimental when cross building to the MIPS32 architecture, i.e. in the other cases what was needed was being included by sheer luck. In file included from builtin-sched.c:11: util/thread.h: In function 'thread__free_stitch_list': util/thread.h:169:3: error: implicit declaration of function 'free' [-Werror=implicit-function-declaration] 169 | free(pos); | ^~~~ util/thread.h:169:3: error: incompatible implicit declaration of built-in function 'free' [-Werror] util/thread.h:19:1: note: include '' or provide a declaration of 'free' 18 | #include "callchain.h" +++ |+#include 19 | util/thread.h:174:3: error: incompatible implicit declaration of built-in function 'free' [-Werror] 174 | free(pos); | ^~~~ util/thread.h:174:3: note: include '' or provide a declaration of 'free' Signed-off-by: Kan Liang Reviewed-by: Andi Kleen Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Alexey Budankov Cc: Mathieu Poirier Cc: Michael Ellerman Cc: Namhyung Kim Cc: Pavel Gerasimov Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Stephane Eranian Cc: Vitaly Slobodskoy Link: http://lore.kernel.org/lkml/20200319202517.23423-13-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf callchain: Save previous cursor nodes for LBR stitching approach

2020-04-18T12:05:01+00:00

The cursor nodes which generates from sample are eventually added into callchain. To avoid generating cursor nodes from previous samples again, the previous cursor nodes are also saved for LBR stitching approach. Some option, e.g. hide-unresolved, may hide some LBRs. Add a variable 'valid' in struct callchain_cursor_node to indicate this case. The LBR stitching approach will only append the valid cursor nodes from previous samples later. Signed-off-by: Kan Liang Reviewed-by: Andi Kleen Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Alexey Budankov Cc: Mathieu Poirier Cc: Michael Ellerman Cc: Namhyung Kim Cc: Pavel Gerasimov Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Stephane Eranian Cc: Vitaly Slobodskoy Link: http://lore.kernel.org/lkml/20200319202517.23423-12-kan.liang@linux.intel.com [ Use zfree() instead of open coded equivalent, and use it when freeing members of structs ] Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Save previous sample for LBR stitching approach

2020-04-18T12:05:01+00:00

To retrieve the overwritten LBRs from previous sample for LBR stitching approach, perf has to save the previous sample. Only allocate the struct lbr_stitch once, when LBR stitching approach is enabled and kernel supports hw_idx. Signed-off-by: Kan Liang Reviewed-by: Andi Kleen Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Alexey Budankov Cc: Mathieu Poirier Cc: Michael Ellerman Cc: Namhyung Kim Cc: Pavel Gerasimov Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Stephane Eranian Cc: Vitaly Slobodskoy Link: http://lore.kernel.org/lkml/20200319202517.23423-11-kan.liang@linux.intel.com [ Use zalloc()/zfree() for thread->lbr_stitch ] Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Add a knob for LBR stitch approach

2020-04-18T12:05:01+00:00

The LBR stitch approach should be disabled by default. Because - The stitching approach base on LBR call stack technology. The known limitations of LBR call stack technology still apply to the approach, e.g. Exception handing such as setjmp/longjmp will have calls/returns not match. - This approach is not foolproof. There can be cases where it creates incorrect call stacks from incorrect matches. There is no attempt to validate any matches in another way. The 'lbr_stitch_enable' is used to indicate whether enable LBR stitch approach, which is disabled by default. The following patch will introduce a new option for each tools to enable the LBR stitch approach. Signed-off-by: Kan Liang Reviewed-by: Andi Kleen Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Alexey Budankov Cc: Mathieu Poirier Cc: Michael Ellerman Cc: Namhyung Kim Cc: Pavel Gerasimov Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Stephane Eranian Cc: Vitaly Slobodskoy Link: http://lore.kernel.org/lkml/20200319202517.23423-10-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Rename thread->mg to thread->maps

2019-11-26T14:07:46+00:00

One more step on the merge of 'struct maps' with 'struct map_groups'. Cc: Adrian Hunter Cc: Andi Kleen Cc: Jiri Olsa Cc: Namhyung Kim Link: https://lkml.kernel.org/n/tip-69vcr8pubpym90skxhmbwhiw@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf maps: Merge 'struct maps' with 'struct map_groups'

2019-11-26T14:07:46+00:00

And pick the shortest name: 'struct maps'. The split existed because we used to have two groups of maps, one for functions and one for variables, but that only complicated things, sometimes we needed to figure out what was at some address and then had to first try it on the functions group and if that failed, fall back to the variables one. That split is long gone, so for quite a while we had only one struct maps per struct map_groups, simplify things by combining those structs. First patch is the minimum needed to merge both, follow up patches will rename 'thread->mg' to 'thread->maps', etc. Cc: Adrian Hunter Cc: Andi Kleen Cc: Jiri Olsa Cc: Namhyung Kim Link: https://lkml.kernel.org/n/tip-hom6639ro7020o708trhxh59@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

libperf: Rename the PERF_RECORD_ structs to have a "perf" suffix

2019-08-26T22:39:11+00:00

Even more, to have a "perf_record_" prefix, so that they match the PERF_RECORD_ enum they map to. Cc: Adrian Hunter Cc: Jiri Olsa Cc: Namhyung Kim Link: https://lkml.kernel.org/n/tip-qbabmcz2a0pkzt72liyuz3p8@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf unwind: Fix libunwind when tid != pid

2019-08-16T15:25:57+00:00

Commit e5adfc3e7e77 ("perf map: Synthesize maps only for thread group leader") changed the recording side so that we no longer get mmap events for threads other than the thread group leader (when synthesising these events for threads which exist before perf is started). When a file recorded after this change is loaded, the lack of mmap records mean that unwinding is not set up for any other threads. This can be seen in a simple record/report scenario: perf record --call-graph=dwarf -t $TID perf report If $TID is a process ID then the report will show call graphs, but if $TID is a secondary thread the output is as if --call-graph=none was specified. Following the rationale in that commit, move the libunwind fields into struct map_groups and update the libunwind functions to take this instead of the struct thread. This is only required for unwind__finish_access which must now be called from map_groups__delete and the others are changed for symmetry. Note that unwind__get_entries keeps the thread argument since it is required for symbol lookup and the libdw unwind provider uses the thread ID. Signed-off-by: John Keeping Reviewed-by: Jiri Olsa Cc: Alexander Shishkin Cc: Konstantin Khlebnikov Cc: Namhyung Kim Cc: Peter Zijlstra Fixes: e5adfc3e7e77 ("perf map: Synthesize maps only for thread group leader") Link: http://lkml.kernel.org/r/20190815100146.28842-2-john@metanate.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Remove const from thread read accessors

2019-05-28T21:37:43+00:00

The namespaces and comm fields of a thread are protected by rwsem and require write access for it. So it ended up using a cast to remove the const qualifier. Let's get rid of the const then. Signed-off-by: Namhyung Kim Suggested-by: Arnaldo Carvalho de Melo Cc: Hari Bathini Cc: Jiri Olsa Cc: Krister Johansen Link: http://lkml.kernel.org/r/20190527061149.168640-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo