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![Kan Liang](/assets/img/avatar_default.png)
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 '<stdlib.h>' or provide a declaration of 'free' 18 | #include "callchain.h" +++ |+#include <stdlib.h> 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 '<stdlib.h>' or provide a declaration of 'free' Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Reviewed-by: Andi Kleen <ak@linux.intel.com> Acked-by: Jiri Olsa <jolsa@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexey Budankov <alexey.budankov@linux.intel.com> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Pavel Gerasimov <pavel.gerasimov@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Cc: Stephane Eranian <eranian@google.com> Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com> Link: http://lore.kernel.org/lkml/20200319202517.23423-13-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
160 lines
4.2 KiB
C
160 lines
4.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __PERF_THREAD_H
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#define __PERF_THREAD_H
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#include <linux/refcount.h>
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#include <linux/rbtree.h>
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#include <linux/list.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include "srccode.h"
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#include "symbol_conf.h"
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#include <strlist.h>
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#include <intlist.h>
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#include "rwsem.h"
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#include "event.h"
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#include "callchain.h"
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struct addr_location;
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struct map;
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struct perf_record_namespaces;
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struct thread_stack;
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struct unwind_libunwind_ops;
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struct lbr_stitch {
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struct list_head lists;
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struct list_head free_lists;
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struct perf_sample prev_sample;
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struct callchain_cursor_node *prev_lbr_cursor;
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};
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struct thread {
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union {
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struct rb_node rb_node;
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struct list_head node;
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};
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struct maps *maps;
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pid_t pid_; /* Not all tools update this */
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pid_t tid;
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pid_t ppid;
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int cpu;
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refcount_t refcnt;
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bool comm_set;
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int comm_len;
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bool dead; /* if set thread has exited */
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struct list_head namespaces_list;
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struct rw_semaphore namespaces_lock;
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struct list_head comm_list;
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struct rw_semaphore comm_lock;
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u64 db_id;
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void *priv;
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struct thread_stack *ts;
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struct nsinfo *nsinfo;
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struct srccode_state srccode_state;
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bool filter;
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int filter_entry_depth;
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/* LBR call stack stitch */
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bool lbr_stitch_enable;
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struct lbr_stitch *lbr_stitch;
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};
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struct machine;
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struct namespaces;
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struct comm;
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struct thread *thread__new(pid_t pid, pid_t tid);
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int thread__init_maps(struct thread *thread, struct machine *machine);
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void thread__delete(struct thread *thread);
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struct thread *thread__get(struct thread *thread);
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void thread__put(struct thread *thread);
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static inline void __thread__zput(struct thread **thread)
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{
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thread__put(*thread);
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*thread = NULL;
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}
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#define thread__zput(thread) __thread__zput(&thread)
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static inline void thread__exited(struct thread *thread)
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{
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thread->dead = true;
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}
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struct namespaces *thread__namespaces(struct thread *thread);
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int thread__set_namespaces(struct thread *thread, u64 timestamp,
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struct perf_record_namespaces *event);
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int __thread__set_comm(struct thread *thread, const char *comm, u64 timestamp,
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bool exec);
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static inline int thread__set_comm(struct thread *thread, const char *comm,
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u64 timestamp)
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{
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return __thread__set_comm(thread, comm, timestamp, false);
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}
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int thread__set_comm_from_proc(struct thread *thread);
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int thread__comm_len(struct thread *thread);
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struct comm *thread__comm(const struct thread *thread);
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struct comm *thread__exec_comm(const struct thread *thread);
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const char *thread__comm_str(struct thread *thread);
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int thread__insert_map(struct thread *thread, struct map *map);
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int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp, bool do_maps_clone);
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size_t thread__fprintf(struct thread *thread, FILE *fp);
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struct thread *thread__main_thread(struct machine *machine, struct thread *thread);
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struct map *thread__find_map(struct thread *thread, u8 cpumode, u64 addr,
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struct addr_location *al);
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struct map *thread__find_map_fb(struct thread *thread, u8 cpumode, u64 addr,
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struct addr_location *al);
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struct symbol *thread__find_symbol(struct thread *thread, u8 cpumode,
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u64 addr, struct addr_location *al);
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struct symbol *thread__find_symbol_fb(struct thread *thread, u8 cpumode,
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u64 addr, struct addr_location *al);
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void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
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struct addr_location *al);
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int thread__memcpy(struct thread *thread, struct machine *machine,
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void *buf, u64 ip, int len, bool *is64bit);
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static inline void *thread__priv(struct thread *thread)
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{
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return thread->priv;
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}
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static inline void thread__set_priv(struct thread *thread, void *p)
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{
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thread->priv = p;
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}
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static inline bool thread__is_filtered(struct thread *thread)
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{
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if (symbol_conf.comm_list &&
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!strlist__has_entry(symbol_conf.comm_list, thread__comm_str(thread))) {
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return true;
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}
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if (symbol_conf.pid_list &&
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!intlist__has_entry(symbol_conf.pid_list, thread->pid_)) {
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return true;
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}
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if (symbol_conf.tid_list &&
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!intlist__has_entry(symbol_conf.tid_list, thread->tid)) {
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return true;
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}
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return false;
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}
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void thread__free_stitch_list(struct thread *thread);
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#endif /* __PERF_THREAD_H */
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