From: Hao Luo <haoluo@google.com>
To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
cgroups@vger.kernel.org, netdev@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
KP Singh <kpsingh@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Jiri Olsa <jolsa@kernel.org>, Michal Koutny <mkoutny@suse.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
David Rientjes <rientjes@google.com>,
Stanislav Fomichev <sdf@google.com>,
Shakeel Butt <shakeelb@google.com>,
Yosry Ahmed <yosryahmed@google.com>, Hao Luo <haoluo@google.com>
Subject: [RESEND PATCH bpf-next v9 3/5] cgroup: bpf: enable bpf programs to integrate with rstat
Date: Wed, 24 Aug 2022 16:31:15 -0700 [thread overview]
Message-ID: <20220824233117.1312810-4-haoluo@google.com> (raw)
In-Reply-To: <20220824233117.1312810-1-haoluo@google.com>
From: Yosry Ahmed <yosryahmed@google.com>
Enable bpf programs to make use of rstat to collect cgroup hierarchical
stats efficiently:
- Add cgroup_rstat_updated() kfunc, for bpf progs that collect stats.
- Add cgroup_rstat_flush() sleepable kfunc, for bpf progs that read stats.
- Add an empty bpf_rstat_flush() hook that is called during rstat
flushing, for bpf progs that flush stats to attach to. Attaching a bpf
prog to this hook effectively registers it as a flush callback.
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hao Luo <haoluo@google.com>
---
kernel/cgroup/rstat.c | 48 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index feb59380c896..793ecff29038 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -3,6 +3,10 @@
#include <linux/sched/cputime.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
+
static DEFINE_SPINLOCK(cgroup_rstat_lock);
static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
@@ -141,6 +145,31 @@ static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
return pos;
}
+/*
+ * A hook for bpf stat collectors to attach to and flush their stats.
+ * Together with providing bpf kfuncs for cgroup_rstat_updated() and
+ * cgroup_rstat_flush(), this enables a complete workflow where bpf progs that
+ * collect cgroup stats can integrate with rstat for efficient flushing.
+ *
+ * A static noinline declaration here could cause the compiler to optimize away
+ * the function. A global noinline declaration will keep the definition, but may
+ * optimize away the callsite. Therefore, __weak is needed to ensure that the
+ * call is still emitted, by telling the compiler that we don't know what the
+ * function might eventually be.
+ *
+ * __diag_* below are needed to dismiss the missing prototype warning.
+ */
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+ "kfuncs which will be used in BPF programs");
+
+__weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
+ struct cgroup *parent, int cpu)
+{
+}
+
+__diag_pop();
+
/* see cgroup_rstat_flush() */
static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
__releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
@@ -168,6 +197,7 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
struct cgroup_subsys_state *css;
cgroup_base_stat_flush(pos, cpu);
+ bpf_rstat_flush(pos, cgroup_parent(pos), cpu);
rcu_read_lock();
list_for_each_entry_rcu(css, &pos->rstat_css_list,
@@ -501,3 +531,21 @@ void cgroup_base_stat_cputime_show(struct seq_file *seq)
seq_printf(seq, "core_sched.force_idle_usec %llu\n", forceidle_time);
#endif
}
+
+/* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
+BTF_SET8_START(bpf_rstat_kfunc_ids)
+BTF_ID_FLAGS(func, cgroup_rstat_updated)
+BTF_ID_FLAGS(func, cgroup_rstat_flush, KF_SLEEPABLE)
+BTF_SET8_END(bpf_rstat_kfunc_ids)
+
+static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
+ .owner = THIS_MODULE,
+ .set = &bpf_rstat_kfunc_ids,
+};
+
+static int __init bpf_rstat_kfunc_init(void)
+{
+ return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
+ &bpf_rstat_kfunc_set);
+}
+late_initcall(bpf_rstat_kfunc_init);
--
2.37.1.595.g718a3a8f04-goog
next prev parent reply other threads:[~2022-08-24 23:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-24 23:31 [RESEND PATCH bpf-next v9 0/5] bpf: rstat: cgroup hierarchical Hao Luo
2022-08-24 23:31 ` [RESEND PATCH bpf-next v9 1/5] bpf: Introduce cgroup iter Hao Luo
2022-08-25 23:00 ` Yonghong Song
2022-08-29 18:07 ` Hao Luo
2022-08-24 23:31 ` [RESEND PATCH bpf-next v9 2/5] selftests/bpf: Test cgroup_iter Hao Luo
2022-08-24 23:31 ` Hao Luo [this message]
2022-08-24 23:31 ` [RESEND PATCH bpf-next v9 4/5] selftests/bpf: extend cgroup helpers Hao Luo
2022-08-24 23:31 ` [RESEND PATCH bpf-next v9 5/5] selftests/bpf: add a selftest for cgroup hierarchical stats collection Hao Luo
2022-08-25 2:09 ` Alexei Starovoitov
2022-08-25 2:41 ` Yosry Ahmed
2022-08-25 18:43 ` Alexei Starovoitov
2022-08-25 18:45 ` Yosry Ahmed
2022-08-25 18:52 ` Hao Luo
2022-08-25 0:29 ` [RESEND PATCH bpf-next v9 0/5] bpf: rstat: cgroup hierarchical Alexei Starovoitov
2022-08-25 0:42 ` Hao Luo
2022-08-25 0:47 ` Alexei Starovoitov
2022-08-25 0:48 ` Hao Luo
2022-08-25 18:40 ` patchwork-bot+netdevbpf
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