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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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236a3bbd5c
Occassionally events (e.g., context-switch, sched tracepoints) are losing
the conversion of sample data associated with a thread. For example:
$ perf record -e sched:sched_switch -c 1 -a -- sleep 5
$ perf script
<selected events shown>
ls 30482 [000] 1379727.583037: sched:sched_switch: prev_comm=ls prev_pid=30482 ...
ls 30482 [000] 1379727.586339: sched:sched_switch: prev_comm=ls prev_pid=30482 ...
:30482 30482 [000] 1379727.589462: sched:sched_switch: prev_comm=ls prev_pid=30482 ...
The last line lost the conversion from tid to comm. If you look at the events
(perf script -D) you see why - a SAMPLE event is generated after the EXIT:
0 1379727589449774 0x1540b0 [0x38]: PERF_RECORD_EXIT(30482:30482):(30482:30482)
0 1379727589462497 0x1540e8 [0x80]: PERF_RECORD_SAMPLE(IP, 1): 30482/30482: 0xffffffff816416f1 period: 1 addr: 0
... thread: :30482:30482
When perf processes the EXIT event the thread is moved to the dead_threads
list. When the SAMPLE event is processed no thread exists for the pid so a new
one is created by machine__findnew_thread.
This patch address the problem by delaying the move to the dead_threads list
until the tid is re-used (per Adrian's suggestion).
With this patch we get the previous example shows:
ls 30482 [000] 1379727.583037: sched:sched_switch: prev_comm=ls prev_pid=30482 ...
ls 30482 [000] 1379727.586339: sched:sched_switch: prev_comm=ls prev_pid=30482 ...
ls 30482 [000] 1379727.589462: sched:sched_switch: prev_comm=ls prev_pid=30482 ...
and
0 1379727589449774 0x1540b0 [0x38]: PERF_RECORD_EXIT(30482:30482):(30482:30482)
0 1379727589462497 0x1540e8 [0x80]: PERF_RECORD_SAMPLE(IP, 1): 30482/30482: 0xffffffff816416f1 period: 1 addr: 0
... thread: ls:30482
v4: per Arnaldo's request add dead flag to thread struct and set when task exits
v3: re-do from a time based check to a delayed move to dead_threads list
v2: Rebased to latest perf/core branch. Changed time comparison to use
a macro which explicitly shows the time basis
Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1376491767-84171-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
65 lines
1.5 KiB
C
65 lines
1.5 KiB
C
#ifndef __PERF_THREAD_H
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#define __PERF_THREAD_H
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#include <linux/rbtree.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include "symbol.h"
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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 map_groups mg;
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pid_t tid;
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pid_t ppid;
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char shortname[3];
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bool comm_set;
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bool dead; /* if set thread has exited */
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char *comm;
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int comm_len;
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void *priv;
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};
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struct machine;
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struct thread *thread__new(pid_t tid);
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void thread__delete(struct thread *self);
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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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int thread__set_comm(struct thread *self, const char *comm);
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int thread__comm_len(struct thread *self);
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void thread__insert_map(struct thread *self, struct map *map);
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int thread__fork(struct thread *self, struct thread *parent);
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size_t thread__fprintf(struct thread *thread, FILE *fp);
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static inline struct map *thread__find_map(struct thread *self,
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enum map_type type, u64 addr)
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{
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return self ? map_groups__find(&self->mg, type, addr) : NULL;
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}
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void thread__find_addr_map(struct thread *thread, struct machine *machine,
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u8 cpumode, enum map_type type, u64 addr,
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struct addr_location *al);
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void thread__find_addr_location(struct thread *thread, struct machine *machine,
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u8 cpumode, enum map_type type, u64 addr,
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struct addr_location *al);
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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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#endif /* __PERF_THREAD_H */
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