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perf stat: Support old kernels for bperf cgroup counting

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The recent change in the cgroup will break the backward compatiblity in
the BPF program.  It should support both old and new kernels using BPF
CO-RE technique.

Like the task_struct->__state handling in the offcpu analysis, we can
check the field name in the cgroup struct.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: bpf@vger.kernel.org
Cc: cgroups@vger.kernel.org
Cc: zefan li <lizefan.x@bytedance.com>
Link: http://lore.kernel.org/lkml/20221011052808.282394-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Namhyung Kim 2022-10-10 22:28:08 -07:00 committed by Arnaldo Carvalho de Melo
parent 9c9155a350
commit f21cb52036
1 changed files with 28 additions and 1 deletions
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29
tools/perf/util/bpf_skel/bperf_cgroup.bpf.c
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@ -43,6 +43,18 @@ struct {
__uint(value_size, sizeof(struct bpf_perf_event_value));
} cgrp_readings SEC(".maps");
/* new kernel cgroup definition */
struct cgroup___new {
int level;
struct cgroup *ancestors[];
} __attribute__((preserve_access_index));
/* old kernel cgroup definition */
struct cgroup___old {
int level;
u64 ancestor_ids[];
} __attribute__((preserve_access_index));
const volatile __u32 num_events = 1;
const volatile __u32 num_cpus = 1;
@ -50,6 +62,21 @@ int enabled = 0;
int use_cgroup_v2 = 0;
int perf_subsys_id = -1;
static inline __u64 get_cgroup_v1_ancestor_id(struct cgroup *cgrp, int level)
{
/* recast pointer to capture new type for compiler */
struct cgroup___new *cgrp_new = (void *)cgrp;
if (bpf_core_field_exists(cgrp_new->ancestors)) {
return BPF_CORE_READ(cgrp_new, ancestors[level], kn, id);
} else {
/* recast pointer to capture old type for compiler */
struct cgroup___old *cgrp_old = (void *)cgrp;
return BPF_CORE_READ(cgrp_old, ancestor_ids[level]);
}
}
static inline int get_cgroup_v1_idx(__u32 *cgrps, int size)
{
struct task_struct *p = (void *)bpf_get_current_task();
@ -77,7 +104,7 @@ static inline int get_cgroup_v1_idx(__u32 *cgrps, int size)
break;
// convert cgroup-id to a map index
cgrp_id = BPF_CORE_READ(cgrp, ancestors[i], kn, id);
cgrp_id = get_cgroup_v1_ancestor_id(cgrp, i);
elem = bpf_map_lookup_elem(&cgrp_idx, &cgrp_id);
if (!elem)
continue;