| Message ID | 20240904123103.732507-2-wutengda@huaweicloud.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | perf stat: Support inherit events for bperf | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
Hello, On Wed, Sep 04, 2024 at 12:31:02PM +0000, Tengda Wu wrote: > bperf has a nice ability to share PMUs, but it still does not support > inherit events during fork(), resulting in some deviations in its stat > results compared with perf. > > perf stat result: > $ ./perf stat -e cycles,instructions -- ./perf test -w sqrtloop > > Performance counter stats for './perf test -w sqrtloop': > > 2,316,038,116 cycles > 2,859,350,725 instructions # 1.23 insn per cycle > > 1.009603637 seconds time elapsed > > 1.004196000 seconds user > 0.003950000 seconds sys > > bperf stat result: > $ ./perf stat --bpf-counters -e cycles,instructions -- ./perf test -w sqrtloop > > Performance counter stats for './perf test -w sqrtloop': > > 18,762,093 cycles > 23,487,766 instructions # 1.25 insn per cycle > > 1.008913769 seconds time elapsed > > 1.003248000 seconds user > 0.004069000 seconds sys > > In order to support event inheritance, two new bpf programs are added > to monitor the fork and exit of tasks respectively. When a task is > created, add it to the filter map to enable counting, and reuse the > `accum_key` of its parent task to count together with the parent task. > When a task exits, remove it from the filter map to disable counting. Right, I think we may need this for other BPF programs. > > After support: > $ ./perf stat --bpf-counters -e cycles,instructions -- ./perf test -w sqrtloop > > Performance counter stats for './perf test -w sqrtloop': > > 2,316,543,537 cycles > 2,859,677,779 instructions # 1.23 insn per cycle > > 1.009566332 seconds time elapsed > > 1.004414000 seconds user > 0.003545000 seconds sys > > Signed-off-by: Tengda Wu <wutengda@huaweicloud.com> > --- > tools/perf/util/bpf_counter.c | 9 +-- > tools/perf/util/bpf_skel/bperf_follower.bpf.c | 75 +++++++++++++++++-- > tools/perf/util/bpf_skel/bperf_u.h | 5 ++ > 3 files changed, 78 insertions(+), 11 deletions(-) > > diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c > index 7a8af60e0f51..e07ff04b934f 100644 > --- a/tools/perf/util/bpf_counter.c > +++ b/tools/perf/util/bpf_counter.c > @@ -529,9 +529,6 @@ static int bperf__load(struct evsel *evsel, struct target *target) > /* set up reading map */ > bpf_map__set_max_entries(evsel->follower_skel->maps.accum_readings, > filter_entry_cnt); > - /* set up follower filter based on target */ > - bpf_map__set_max_entries(evsel->follower_skel->maps.filter, > - filter_entry_cnt); > err = bperf_follower_bpf__load(evsel->follower_skel); > if (err) { > pr_err("Failed to load follower skeleton\n"); > @@ -543,6 +540,7 @@ static int bperf__load(struct evsel *evsel, struct target *target) > for (i = 0; i < filter_entry_cnt; i++) { > int filter_map_fd; > __u32 key; > + struct bperf_filter_value fval = { i, 0 }; > > if (filter_type == BPERF_FILTER_PID || > filter_type == BPERF_FILTER_TGID) > @@ -553,10 +551,11 @@ static int bperf__load(struct evsel *evsel, struct target *target) > break; > > filter_map_fd = bpf_map__fd(evsel->follower_skel->maps.filter); > - bpf_map_update_elem(filter_map_fd, &key, &i, BPF_ANY); > + bpf_map_update_elem(filter_map_fd, &key, &fval, BPF_ANY); > } > > evsel->follower_skel->bss->type = filter_type; > + evsel->follower_skel->bss->init_filter_entries = filter_entry_cnt; Do you need this in the BPF program? > > err = bperf_follower_bpf__attach(evsel->follower_skel); > > @@ -623,7 +622,7 @@ static int bperf__read(struct evsel *evsel) > bperf_sync_counters(evsel); > reading_map_fd = bpf_map__fd(skel->maps.accum_readings); > > - for (i = 0; i < bpf_map__max_entries(skel->maps.accum_readings); i++) { > + for (i = 0; i < skel->bss->init_filter_entries; i++) { > struct perf_cpu entry; > __u32 cpu; > > diff --git a/tools/perf/util/bpf_skel/bperf_follower.bpf.c b/tools/perf/util/bpf_skel/bperf_follower.bpf.c > index f193998530d4..59fab421526a 100644 > --- a/tools/perf/util/bpf_skel/bperf_follower.bpf.c > +++ b/tools/perf/util/bpf_skel/bperf_follower.bpf.c > @@ -5,6 +5,8 @@ > #include <bpf/bpf_tracing.h> > #include "bperf_u.h" > > +#define MAX_ENTRIES 102400 > + > struct { > __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); > __uint(key_size, sizeof(__u32)); > @@ -22,25 +24,29 @@ struct { > struct { > __uint(type, BPF_MAP_TYPE_HASH); > __uint(key_size, sizeof(__u32)); > - __uint(value_size, sizeof(__u32)); > + __uint(value_size, sizeof(struct bperf_filter_value)); > + __uint(max_entries, MAX_ENTRIES); > + __uint(map_flags, BPF_F_NO_PREALLOC); > } filter SEC(".maps"); > > enum bperf_filter_type type = 0; > int enabled = 0; > +__u32 init_filter_entries = 0; > > SEC("fexit/XXX") > int BPF_PROG(fexit_XXX) > { > struct bpf_perf_event_value *diff_val, *accum_val; > __u32 filter_key, zero = 0; > - __u32 *accum_key; > + __u32 accum_key; > + struct bperf_filter_value *fval; > > if (!enabled) > return 0; > > switch (type) { > case BPERF_FILTER_GLOBAL: > - accum_key = &zero; > + accum_key = zero; > goto do_add; > case BPERF_FILTER_CPU: > filter_key = bpf_get_smp_processor_id(); > @@ -55,16 +61,20 @@ int BPF_PROG(fexit_XXX) > return 0; > } > > - accum_key = bpf_map_lookup_elem(&filter, &filter_key); > - if (!accum_key) > + fval = bpf_map_lookup_elem(&filter, &filter_key); > + if (!fval) > return 0; > > + accum_key = fval->accum_key; > + if (fval->exited) > + bpf_map_delete_elem(&filter, &filter_key); > + > do_add: > diff_val = bpf_map_lookup_elem(&diff_readings, &zero); > if (!diff_val) > return 0; > > - accum_val = bpf_map_lookup_elem(&accum_readings, accum_key); > + accum_val = bpf_map_lookup_elem(&accum_readings, &accum_key); > if (!accum_val) > return 0; > > @@ -75,4 +85,57 @@ int BPF_PROG(fexit_XXX) > return 0; > } > > +SEC("tp_btf/task_newtask") > +int BPF_PROG(on_newtask, struct task_struct *task, __u64 clone_flags) > +{ > + __u32 parent_pid, child_pid; > + struct bperf_filter_value *parent_fval; > + struct bperf_filter_value child_fval = { 0 }; > + > + if (!enabled) > + return 0; > + > + if (type != BPERF_FILTER_PID && type != BPERF_FILTER_TGID) > + return 0; I think you can load/attach this program only if the type is either PID or TGID. Then it'd reduce the overhead. > + > + parent_pid = bpf_get_current_pid_tgid() >> 32; > + child_pid = task->pid; > + > + /* Check if the current task is one of the target tasks to be counted */ > + parent_fval = bpf_map_lookup_elem(&filter, &parent_pid); > + if (!parent_fval) > + return 0; > + > + /* Start counting for the new task by adding it into filter map, > + * inherit the accum key of its parent task so that they can be > + * counted together. > + */ > + child_fval.accum_key = parent_fval->accum_key; > + child_fval.exited = 0; > + bpf_map_update_elem(&filter, &child_pid, &child_fval, BPF_NOEXIST); > + > + return 0; > +} > + > +SEC("tp_btf/sched_process_exit") > +int BPF_PROG(on_exittask, struct task_struct *task) > +{ > + __u32 pid; > + struct bperf_filter_value *fval; > + > + if (!enabled) > + return 0; > + > + if (type != BPERF_FILTER_PID && type != BPERF_FILTER_TGID) > + return 0; Ditto. Thanks, Namhyung > + > + /* Stop counting for this task by removing it from filter map */ > + pid = task->pid; > + fval = bpf_map_lookup_elem(&filter, &pid); > + if (fval) > + fval->exited = 1; > + > + return 0; > +} > + > char LICENSE[] SEC("license") = "Dual BSD/GPL"; > diff --git a/tools/perf/util/bpf_skel/bperf_u.h b/tools/perf/util/bpf_skel/bperf_u.h > index 1ce0c2c905c1..4a4a753980be 100644 > --- a/tools/perf/util/bpf_skel/bperf_u.h > +++ b/tools/perf/util/bpf_skel/bperf_u.h > @@ -11,4 +11,9 @@ enum bperf_filter_type { > BPERF_FILTER_TGID, > }; > > +struct bperf_filter_value { > + __u32 accum_key; > + __u8 exited; > +}; > + > #endif /* __BPERF_STAT_U_H */ > -- > 2.34.1 >
On 2024/9/5 12:01, Namhyung Kim wrote: > Hello, > > On Wed, Sep 04, 2024 at 12:31:02PM +0000, Tengda Wu wrote: >> bperf has a nice ability to share PMUs, but it still does not support >> inherit events during fork(), resulting in some deviations in its stat >> results compared with perf. >> >> perf stat result: >> $ ./perf stat -e cycles,instructions -- ./perf test -w sqrtloop >> >> Performance counter stats for './perf test -w sqrtloop': >> >> 2,316,038,116 cycles >> 2,859,350,725 instructions # 1.23 insn per cycle >> >> 1.009603637 seconds time elapsed >> >> 1.004196000 seconds user >> 0.003950000 seconds sys >> >> bperf stat result: >> $ ./perf stat --bpf-counters -e cycles,instructions -- ./perf test -w sqrtloop >> >> Performance counter stats for './perf test -w sqrtloop': >> >> 18,762,093 cycles >> 23,487,766 instructions # 1.25 insn per cycle >> >> 1.008913769 seconds time elapsed >> >> 1.003248000 seconds user >> 0.004069000 seconds sys >> >> In order to support event inheritance, two new bpf programs are added >> to monitor the fork and exit of tasks respectively. When a task is >> created, add it to the filter map to enable counting, and reuse the >> `accum_key` of its parent task to count together with the parent task. >> When a task exits, remove it from the filter map to disable counting. > > Right, I think we may need this for other BPF programs. > >> >> After support: >> $ ./perf stat --bpf-counters -e cycles,instructions -- ./perf test -w sqrtloop >> >> Performance counter stats for './perf test -w sqrtloop': >> >> 2,316,543,537 cycles >> 2,859,677,779 instructions # 1.23 insn per cycle >> >> 1.009566332 seconds time elapsed >> >> 1.004414000 seconds user >> 0.003545000 seconds sys >> >> Signed-off-by: Tengda Wu <wutengda@huaweicloud.com> >> --- >> tools/perf/util/bpf_counter.c | 9 +-- >> tools/perf/util/bpf_skel/bperf_follower.bpf.c | 75 +++++++++++++++++-- >> tools/perf/util/bpf_skel/bperf_u.h | 5 ++ >> 3 files changed, 78 insertions(+), 11 deletions(-) >> >> diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c >> index 7a8af60e0f51..e07ff04b934f 100644 >> --- a/tools/perf/util/bpf_counter.c >> +++ b/tools/perf/util/bpf_counter.c >> @@ -529,9 +529,6 @@ static int bperf__load(struct evsel *evsel, struct target *target) >> /* set up reading map */ >> bpf_map__set_max_entries(evsel->follower_skel->maps.accum_readings, >> filter_entry_cnt); >> - /* set up follower filter based on target */ >> - bpf_map__set_max_entries(evsel->follower_skel->maps.filter, >> - filter_entry_cnt); >> err = bperf_follower_bpf__load(evsel->follower_skel); >> if (err) { >> pr_err("Failed to load follower skeleton\n"); >> @@ -543,6 +540,7 @@ static int bperf__load(struct evsel *evsel, struct target *target) >> for (i = 0; i < filter_entry_cnt; i++) { >> int filter_map_fd; >> __u32 key; >> + struct bperf_filter_value fval = { i, 0 }; >> >> if (filter_type == BPERF_FILTER_PID || >> filter_type == BPERF_FILTER_TGID) >> @@ -553,10 +551,11 @@ static int bperf__load(struct evsel *evsel, struct target *target) >> break; >> >> filter_map_fd = bpf_map__fd(evsel->follower_skel->maps.filter); >> - bpf_map_update_elem(filter_map_fd, &key, &i, BPF_ANY); >> + bpf_map_update_elem(filter_map_fd, &key, &fval, BPF_ANY); >> } >> >> evsel->follower_skel->bss->type = filter_type; >> + evsel->follower_skel->bss->init_filter_entries = filter_entry_cnt; > > Do you need this in the BPF program? No need. Actually, this variable is only used in bperf__read(). Since bperf__read() does not have a `struct target` parameter, it is not possible to check the filter_entry_cnt value again through bperf_check_target(). We can only put it in a global scope, one way is the current implementation, and another way is to declare a global variable in bpf_counter. Maybe the second way is more appropriate? If so, I will modify it. > >> >> err = bperf_follower_bpf__attach(evsel->follower_skel); >> >> @@ -623,7 +622,7 @@ static int bperf__read(struct evsel *evsel) >> bperf_sync_counters(evsel); >> reading_map_fd = bpf_map__fd(skel->maps.accum_readings); >> >> - for (i = 0; i < bpf_map__max_entries(skel->maps.accum_readings); i++) { >> + for (i = 0; i < skel->bss->init_filter_entries; i++) { >> struct perf_cpu entry; >> __u32 cpu; >> >> diff --git a/tools/perf/util/bpf_skel/bperf_follower.bpf.c b/tools/perf/util/bpf_skel/bperf_follower.bpf.c >> index f193998530d4..59fab421526a 100644 >> --- a/tools/perf/util/bpf_skel/bperf_follower.bpf.c >> +++ b/tools/perf/util/bpf_skel/bperf_follower.bpf.c >> @@ -5,6 +5,8 @@ >> #include <bpf/bpf_tracing.h> >> #include "bperf_u.h" >> >> +#define MAX_ENTRIES 102400 >> + >> struct { >> __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); >> __uint(key_size, sizeof(__u32)); >> @@ -22,25 +24,29 @@ struct { >> struct { >> __uint(type, BPF_MAP_TYPE_HASH); >> __uint(key_size, sizeof(__u32)); >> - __uint(value_size, sizeof(__u32)); >> + __uint(value_size, sizeof(struct bperf_filter_value)); >> + __uint(max_entries, MAX_ENTRIES); >> + __uint(map_flags, BPF_F_NO_PREALLOC); >> } filter SEC(".maps"); >> >> enum bperf_filter_type type = 0; >> int enabled = 0; >> +__u32 init_filter_entries = 0; >> >> SEC("fexit/XXX") >> int BPF_PROG(fexit_XXX) >> { >> struct bpf_perf_event_value *diff_val, *accum_val; >> __u32 filter_key, zero = 0; >> - __u32 *accum_key; >> + __u32 accum_key; >> + struct bperf_filter_value *fval; >> >> if (!enabled) >> return 0; >> >> switch (type) { >> case BPERF_FILTER_GLOBAL: >> - accum_key = &zero; >> + accum_key = zero; >> goto do_add; >> case BPERF_FILTER_CPU: >> filter_key = bpf_get_smp_processor_id(); >> @@ -55,16 +61,20 @@ int BPF_PROG(fexit_XXX) >> return 0; >> } >> >> - accum_key = bpf_map_lookup_elem(&filter, &filter_key); >> - if (!accum_key) >> + fval = bpf_map_lookup_elem(&filter, &filter_key); >> + if (!fval) >> return 0; >> >> + accum_key = fval->accum_key; >> + if (fval->exited) >> + bpf_map_delete_elem(&filter, &filter_key); >> + >> do_add: >> diff_val = bpf_map_lookup_elem(&diff_readings, &zero); >> if (!diff_val) >> return 0; >> >> - accum_val = bpf_map_lookup_elem(&accum_readings, accum_key); >> + accum_val = bpf_map_lookup_elem(&accum_readings, &accum_key); >> if (!accum_val) >> return 0; >> >> @@ -75,4 +85,57 @@ int BPF_PROG(fexit_XXX) >> return 0; >> } >> >> +SEC("tp_btf/task_newtask") >> +int BPF_PROG(on_newtask, struct task_struct *task, __u64 clone_flags) >> +{ >> + __u32 parent_pid, child_pid; >> + struct bperf_filter_value *parent_fval; >> + struct bperf_filter_value child_fval = { 0 }; >> + >> + if (!enabled) >> + return 0; >> + >> + if (type != BPERF_FILTER_PID && type != BPERF_FILTER_TGID) >> + return 0; > > I think you can load/attach this program only if the type is either > PID or TGID. Then it'd reduce the overhead. Great suggestion, I'll give it a try. > >> + >> + parent_pid = bpf_get_current_pid_tgid() >> 32; >> + child_pid = task->pid; >> + >> + /* Check if the current task is one of the target tasks to be counted */ >> + parent_fval = bpf_map_lookup_elem(&filter, &parent_pid); >> + if (!parent_fval) >> + return 0; >> + >> + /* Start counting for the new task by adding it into filter map, >> + * inherit the accum key of its parent task so that they can be >> + * counted together. >> + */ >> + child_fval.accum_key = parent_fval->accum_key; >> + child_fval.exited = 0; >> + bpf_map_update_elem(&filter, &child_pid, &child_fval, BPF_NOEXIST); >> + >> + return 0; >> +} >> + >> +SEC("tp_btf/sched_process_exit") >> +int BPF_PROG(on_exittask, struct task_struct *task) >> +{ >> + __u32 pid; >> + struct bperf_filter_value *fval; >> + >> + if (!enabled) >> + return 0; >> + >> + if (type != BPERF_FILTER_PID && type != BPERF_FILTER_TGID) >> + return 0; > > Ditto. > > Thanks, > Namhyung > >> + >> + /* Stop counting for this task by removing it from filter map */ >> + pid = task->pid; >> + fval = bpf_map_lookup_elem(&filter, &pid); >> + if (fval) >> + fval->exited = 1; >> + >> + return 0; >> +} >> + >> char LICENSE[] SEC("license") = "Dual BSD/GPL"; >> diff --git a/tools/perf/util/bpf_skel/bperf_u.h b/tools/perf/util/bpf_skel/bperf_u.h >> index 1ce0c2c905c1..4a4a753980be 100644 >> --- a/tools/perf/util/bpf_skel/bperf_u.h >> +++ b/tools/perf/util/bpf_skel/bperf_u.h >> @@ -11,4 +11,9 @@ enum bperf_filter_type { >> BPERF_FILTER_TGID, >> }; >> >> +struct bperf_filter_value { >> + __u32 accum_key; >> + __u8 exited; >> +}; >> + >> #endif /* __BPERF_STAT_U_H */ >> -- >> 2.34.1 >>
diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c index 7a8af60e0f51..e07ff04b934f 100644 --- a/tools/perf/util/bpf_counter.c +++ b/tools/perf/util/bpf_counter.c @@ -529,9 +529,6 @@ static int bperf__load(struct evsel *evsel, struct target *target) /* set up reading map */ bpf_map__set_max_entries(evsel->follower_skel->maps.accum_readings, filter_entry_cnt); - /* set up follower filter based on target */ - bpf_map__set_max_entries(evsel->follower_skel->maps.filter, - filter_entry_cnt); err = bperf_follower_bpf__load(evsel->follower_skel); if (err) { pr_err("Failed to load follower skeleton\n"); @@ -543,6 +540,7 @@ static int bperf__load(struct evsel *evsel, struct target *target) for (i = 0; i < filter_entry_cnt; i++) { int filter_map_fd; __u32 key; + struct bperf_filter_value fval = { i, 0 }; if (filter_type == BPERF_FILTER_PID || filter_type == BPERF_FILTER_TGID) @@ -553,10 +551,11 @@ static int bperf__load(struct evsel *evsel, struct target *target) break; filter_map_fd = bpf_map__fd(evsel->follower_skel->maps.filter); - bpf_map_update_elem(filter_map_fd, &key, &i, BPF_ANY); + bpf_map_update_elem(filter_map_fd, &key, &fval, BPF_ANY); } evsel->follower_skel->bss->type = filter_type; + evsel->follower_skel->bss->init_filter_entries = filter_entry_cnt; err = bperf_follower_bpf__attach(evsel->follower_skel); @@ -623,7 +622,7 @@ static int bperf__read(struct evsel *evsel) bperf_sync_counters(evsel); reading_map_fd = bpf_map__fd(skel->maps.accum_readings); - for (i = 0; i < bpf_map__max_entries(skel->maps.accum_readings); i++) { + for (i = 0; i < skel->bss->init_filter_entries; i++) { struct perf_cpu entry; __u32 cpu; diff --git a/tools/perf/util/bpf_skel/bperf_follower.bpf.c b/tools/perf/util/bpf_skel/bperf_follower.bpf.c index f193998530d4..59fab421526a 100644 --- a/tools/perf/util/bpf_skel/bperf_follower.bpf.c +++ b/tools/perf/util/bpf_skel/bperf_follower.bpf.c @@ -5,6 +5,8 @@ #include <bpf/bpf_tracing.h> #include "bperf_u.h" +#define MAX_ENTRIES 102400 + struct { __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); __uint(key_size, sizeof(__u32)); @@ -22,25 +24,29 @@ struct { struct { __uint(type, BPF_MAP_TYPE_HASH); __uint(key_size, sizeof(__u32)); - __uint(value_size, sizeof(__u32)); + __uint(value_size, sizeof(struct bperf_filter_value)); + __uint(max_entries, MAX_ENTRIES); + __uint(map_flags, BPF_F_NO_PREALLOC); } filter SEC(".maps"); enum bperf_filter_type type = 0; int enabled = 0; +__u32 init_filter_entries = 0; SEC("fexit/XXX") int BPF_PROG(fexit_XXX) { struct bpf_perf_event_value *diff_val, *accum_val; __u32 filter_key, zero = 0; - __u32 *accum_key; + __u32 accum_key; + struct bperf_filter_value *fval; if (!enabled) return 0; switch (type) { case BPERF_FILTER_GLOBAL: - accum_key = &zero; + accum_key = zero; goto do_add; case BPERF_FILTER_CPU: filter_key = bpf_get_smp_processor_id(); @@ -55,16 +61,20 @@ int BPF_PROG(fexit_XXX) return 0; } - accum_key = bpf_map_lookup_elem(&filter, &filter_key); - if (!accum_key) + fval = bpf_map_lookup_elem(&filter, &filter_key); + if (!fval) return 0; + accum_key = fval->accum_key; + if (fval->exited) + bpf_map_delete_elem(&filter, &filter_key); + do_add: diff_val = bpf_map_lookup_elem(&diff_readings, &zero); if (!diff_val) return 0; - accum_val = bpf_map_lookup_elem(&accum_readings, accum_key); + accum_val = bpf_map_lookup_elem(&accum_readings, &accum_key); if (!accum_val) return 0; @@ -75,4 +85,57 @@ int BPF_PROG(fexit_XXX) return 0; } +SEC("tp_btf/task_newtask") +int BPF_PROG(on_newtask, struct task_struct *task, __u64 clone_flags) +{ + __u32 parent_pid, child_pid; + struct bperf_filter_value *parent_fval; + struct bperf_filter_value child_fval = { 0 }; + + if (!enabled) + return 0; + + if (type != BPERF_FILTER_PID && type != BPERF_FILTER_TGID) + return 0; + + parent_pid = bpf_get_current_pid_tgid() >> 32; + child_pid = task->pid; + + /* Check if the current task is one of the target tasks to be counted */ + parent_fval = bpf_map_lookup_elem(&filter, &parent_pid); + if (!parent_fval) + return 0; + + /* Start counting for the new task by adding it into filter map, + * inherit the accum key of its parent task so that they can be + * counted together. + */ + child_fval.accum_key = parent_fval->accum_key; + child_fval.exited = 0; + bpf_map_update_elem(&filter, &child_pid, &child_fval, BPF_NOEXIST); + + return 0; +} + +SEC("tp_btf/sched_process_exit") +int BPF_PROG(on_exittask, struct task_struct *task) +{ + __u32 pid; + struct bperf_filter_value *fval; + + if (!enabled) + return 0; + + if (type != BPERF_FILTER_PID && type != BPERF_FILTER_TGID) + return 0; + + /* Stop counting for this task by removing it from filter map */ + pid = task->pid; + fval = bpf_map_lookup_elem(&filter, &pid); + if (fval) + fval->exited = 1; + + return 0; +} + char LICENSE[] SEC("license") = "Dual BSD/GPL"; diff --git a/tools/perf/util/bpf_skel/bperf_u.h b/tools/perf/util/bpf_skel/bperf_u.h index 1ce0c2c905c1..4a4a753980be 100644 --- a/tools/perf/util/bpf_skel/bperf_u.h +++ b/tools/perf/util/bpf_skel/bperf_u.h @@ -11,4 +11,9 @@ enum bperf_filter_type { BPERF_FILTER_TGID, }; +struct bperf_filter_value { + __u32 accum_key; + __u8 exited; +}; + #endif /* __BPERF_STAT_U_H */
bperf has a nice ability to share PMUs, but it still does not support inherit events during fork(), resulting in some deviations in its stat results compared with perf. perf stat result: $ ./perf stat -e cycles,instructions -- ./perf test -w sqrtloop Performance counter stats for './perf test -w sqrtloop': 2,316,038,116 cycles 2,859,350,725 instructions # 1.23 insn per cycle 1.009603637 seconds time elapsed 1.004196000 seconds user 0.003950000 seconds sys bperf stat result: $ ./perf stat --bpf-counters -e cycles,instructions -- ./perf test -w sqrtloop Performance counter stats for './perf test -w sqrtloop': 18,762,093 cycles 23,487,766 instructions # 1.25 insn per cycle 1.008913769 seconds time elapsed 1.003248000 seconds user 0.004069000 seconds sys In order to support event inheritance, two new bpf programs are added to monitor the fork and exit of tasks respectively. When a task is created, add it to the filter map to enable counting, and reuse the `accum_key` of its parent task to count together with the parent task. When a task exits, remove it from the filter map to disable counting. After support: $ ./perf stat --bpf-counters -e cycles,instructions -- ./perf test -w sqrtloop Performance counter stats for './perf test -w sqrtloop': 2,316,543,537 cycles 2,859,677,779 instructions # 1.23 insn per cycle 1.009566332 seconds time elapsed 1.004414000 seconds user 0.003545000 seconds sys Signed-off-by: Tengda Wu <wutengda@huaweicloud.com> --- tools/perf/util/bpf_counter.c | 9 +-- tools/perf/util/bpf_skel/bperf_follower.bpf.c | 75 +++++++++++++++++-- tools/perf/util/bpf_skel/bperf_u.h | 5 ++ 3 files changed, 78 insertions(+), 11 deletions(-)