From 54cc54decd79b2c92f4db06001b4b245f38181b7 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Thu, 14 Jul 2016 08:34:42 +0000 Subject: [PATCH] perf evlist: Setup backward mmap state machine Introduce a bkw_mmap_state state machine to evlist: .________________(forbid)_____________. | V NOTREADY --(0)--> RUNNING --(1)--> DATA_PENDING --(2)--> EMPTY ^ ^ | ^ | | |__(forbid)____/ |___(forbid)___/| | | \_________________(3)_______________/ NOTREADY : Backward ring buffers are not ready RUNNING : Backward ring buffers are recording DATA_PENDING : We are required to collect data from backward ring buffers EMPTY : We have collected data from backward ring buffers. (0): Setup backward ring buffer (1): Pause ring buffers for reading (2): Read from ring buffers (3): Resume ring buffers for recording We can't avoid this complexity. Since we deliberately drop records from overwritable ring buffer, there's no way for us to check remaining from ring buffer itself (by checking head and old pointers). Therefore, we need DATA_PENDING and EMPTY state to help us recording what we have done to the ring buffer. In record__mmap_read_evlist(), drive this state machine from DATA_PENDING to EMPTY. In perf_evlist__mmap_per_evsel(), drive this state machine from NOTREADY to RUNNING when creating backward mmap. Signed-off-by: Wang Nan Acked-by: Jiri Olsa Cc: He Kuang Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Nilay Vaish Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1468485287-33422-11-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-record.c | 5 +++ tools/perf/util/evlist.c | 62 +++++++++++++++++++++++++++++++++++++ tools/perf/util/evlist.h | 31 +++++++++++++++++++ 3 files changed, 98 insertions(+) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index dbcb22304398..d4f15e76c98a 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -513,6 +513,9 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli if (!maps) return 0; + if (backward && evlist->bkw_mmap_state != BKW_MMAP_DATA_PENDING) + return 0; + for (i = 0; i < evlist->nr_mmaps; i++) { struct auxtrace_mmap *mm = &maps[i].auxtrace_mmap; @@ -538,6 +541,8 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli if (bytes_written != rec->bytes_written) rc = record__write(rec, &finished_round_event, sizeof(finished_round_event)); + if (backward) + perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_EMPTY); out: return rc; } diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 5beb44faa71d..93ab66415f51 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -15,6 +15,7 @@ #include "evlist.h" #include "evsel.h" #include "debug.h" +#include "asm/bug.h" #include #include "parse-events.h" @@ -44,6 +45,7 @@ void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus, perf_evlist__set_maps(evlist, cpus, threads); fdarray__init(&evlist->pollfd, 64); evlist->workload.pid = -1; + evlist->bkw_mmap_state = BKW_MMAP_NOTREADY; } struct perf_evlist *perf_evlist__new(void) @@ -1068,6 +1070,8 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx, if (!maps) return -1; evlist->backward_mmap = maps; + if (evlist->bkw_mmap_state == BKW_MMAP_NOTREADY) + perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_RUNNING); } } @@ -1972,3 +1976,61 @@ perf_evlist__find_evsel_by_str(struct perf_evlist *evlist, return NULL; } + +void perf_evlist__toggle_bkw_mmap(struct perf_evlist *evlist, + enum bkw_mmap_state state) +{ + enum bkw_mmap_state old_state = evlist->bkw_mmap_state; + enum action { + NONE, + PAUSE, + RESUME, + } action = NONE; + + if (!evlist->backward_mmap) + return; + + switch (old_state) { + case BKW_MMAP_NOTREADY: { + if (state != BKW_MMAP_RUNNING) + goto state_err;; + break; + } + case BKW_MMAP_RUNNING: { + if (state != BKW_MMAP_DATA_PENDING) + goto state_err; + action = PAUSE; + break; + } + case BKW_MMAP_DATA_PENDING: { + if (state != BKW_MMAP_EMPTY) + goto state_err; + break; + } + case BKW_MMAP_EMPTY: { + if (state != BKW_MMAP_RUNNING) + goto state_err; + action = RESUME; + break; + } + default: + WARN_ONCE(1, "Shouldn't get there\n"); + } + + evlist->bkw_mmap_state = state; + + switch (action) { + case PAUSE: + perf_evlist__pause(evlist); + break; + case RESUME: + perf_evlist__resume(evlist); + break; + case NONE: + default: + break; + } + +state_err: + return; +} diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index 6a3d9bdda4bb..20faaab1941c 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -41,6 +41,34 @@ perf_mmap__mmap_len(struct perf_mmap *map) return map->mask + 1 + page_size; } +/* + * State machine of bkw_mmap_state: + * + * .________________(forbid)_____________. + * | V + * NOTREADY --(0)--> RUNNING --(1)--> DATA_PENDING --(2)--> EMPTY + * ^ ^ | ^ | + * | |__(forbid)____/ |___(forbid)___/| + * | | + * \_________________(3)_______________/ + * + * NOTREADY : Backward ring buffers are not ready + * RUNNING : Backward ring buffers are recording + * DATA_PENDING : We are required to collect data from backward ring buffers + * EMPTY : We have collected data from backward ring buffers. + * + * (0): Setup backward ring buffer + * (1): Pause ring buffers for reading + * (2): Read from ring buffers + * (3): Resume ring buffers for recording + */ +enum bkw_mmap_state { + BKW_MMAP_NOTREADY, + BKW_MMAP_RUNNING, + BKW_MMAP_DATA_PENDING, + BKW_MMAP_EMPTY, +}; + struct perf_evlist { struct list_head entries; struct hlist_head heads[PERF_EVLIST__HLIST_SIZE]; @@ -54,6 +82,7 @@ struct perf_evlist { int id_pos; int is_pos; u64 combined_sample_type; + enum bkw_mmap_state bkw_mmap_state; struct { int cork_fd; pid_t pid; @@ -135,6 +164,8 @@ struct perf_evsel *perf_evlist__id2evsel_strict(struct perf_evlist *evlist, struct perf_sample_id *perf_evlist__id2sid(struct perf_evlist *evlist, u64 id); +void perf_evlist__toggle_bkw_mmap(struct perf_evlist *evlist, enum bkw_mmap_state state); + union perf_event *perf_mmap__read_forward(struct perf_mmap *map, bool check_messup); union perf_event *perf_mmap__read_backward(struct perf_mmap *map); -- GitLab