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Message-ID: <20210916162451.709260-3-guro@fb.com>
Date: Thu, 16 Sep 2021 09:24:47 -0700
From: Roman Gushchin <guro@...com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>
CC: Mel Gorman <mgorman@...hsingularity.net>, <bpf@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, Roman Gushchin <guro@...com>
Subject: [PATCH rfc 2/6] bpf: sched: add convenient helpers to identify sched entities
This patch adds 3 helpers useful for dealing with sched entities:
u64 bpf_sched_entity_to_tgidpid(struct sched_entity *se);
u64 bpf_sched_entity_to_cgrpid(struct sched_entity *se);
long bpf_sched_entity_belongs_to_cgrp(struct sched_entity *se, u64 cgrpid);
Sched entity is a basic structure used by the scheduler to represent
schedulable objects: tasks and cgroups (if CONFIG_FAIR_GROUP_SCHED
is enabled). It will be passed as an argument to many bpf hooks, so
scheduler bpf programs need a convenient way to deal with it.
bpf_sched_entity_to_tgidpid() and bpf_sched_entity_to_cgrpid() are
useful to identify a sched entity in userspace terms (pid, tgid and
cgroup id). bpf_sched_entity_belongs_to_cgrp() allows to check whether
a sched entity belongs to sub-tree of a cgroup. It allows to write
cgroup-specific scheduler policies even without enabling the cgroup
cpu controller.
Signed-off-by: Roman Gushchin <guro@...com>
---
include/uapi/linux/bpf.h | 23 +++++++++++
kernel/sched/bpf_sched.c | 74 ++++++++++++++++++++++++++++++++++
scripts/bpf_doc.py | 2 +
tools/include/uapi/linux/bpf.h | 23 +++++++++++
4 files changed, 122 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 6dfbebb8fc8f..199e4a92820d 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4900,6 +4900,26 @@ union bpf_attr {
* **-EINVAL** if *flags* is not zero.
*
* **-ENOENT** if architecture does not support branch records.
+ *
+ * u64 bpf_sched_entity_to_tgidpid(struct sched_entity *se)
+ * Description
+ * Return task's encoded tgid and pid if the sched entity is a task.
+ * Return
+ * Tgid and pid encoded as tgid << 32 \| pid, if *se* is a task. (u64)-1 otherwise.
+ *
+ * u64 bpf_sched_entity_to_cgrpid(struct sched_entity *se)
+ * Description
+ * Return cgroup id if the given sched entity is a cgroup.
+ * Return
+ * Cgroup id, if *se* is a cgroup. (u64)-1 otherwise.
+ *
+ * long bpf_sched_entity_belongs_to_cgrp(struct sched_entity *se, u64 cgrpid)
+ * Description
+ * Checks whether the sched entity belongs to a cgroup or
+ * it's sub-tree. It doesn't require a cgroup CPU controller
+ * to be enabled.
+ * Return
+ * 1 if the sched entity belongs to a cgroup, 0 otherwise.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5079,6 +5099,9 @@ union bpf_attr {
FN(get_attach_cookie), \
FN(task_pt_regs), \
FN(get_branch_snapshot), \
+ FN(sched_entity_to_tgidpid), \
+ FN(sched_entity_to_cgrpid), \
+ FN(sched_entity_belongs_to_cgrp), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/sched/bpf_sched.c b/kernel/sched/bpf_sched.c
index 2f05c186cfd0..ead691dc6e85 100644
--- a/kernel/sched/bpf_sched.c
+++ b/kernel/sched/bpf_sched.c
@@ -42,12 +42,86 @@ int bpf_sched_verify_prog(struct bpf_verifier_log *vlog,
return 0;
}
+BPF_CALL_1(bpf_sched_entity_to_tgidpid, struct sched_entity *, se)
+{
+ if (entity_is_task(se)) {
+ struct task_struct *task = task_of(se);
+
+ return (u64) task->tgid << 32 | task->pid;
+ } else {
+ return (u64) -1;
+ }
+}
+
+BPF_CALL_1(bpf_sched_entity_to_cgrpid, struct sched_entity *, se)
+{
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ if (!entity_is_task(se))
+ return cgroup_id(se->cfs_rq->tg->css.cgroup);
+#endif
+ return (u64) -1;
+}
+
+BPF_CALL_2(bpf_sched_entity_belongs_to_cgrp, struct sched_entity *, se,
+ u64, cgrpid)
+{
+#ifdef CONFIG_CGROUPS
+ struct cgroup *cgrp;
+ int level;
+
+ if (entity_is_task(se))
+ cgrp = task_dfl_cgroup(task_of(se));
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ else
+ cgrp = se->cfs_rq->tg->css.cgroup;
+#endif
+
+ for (level = cgrp->level; level; level--)
+ if (cgrp->ancestor_ids[level] == cgrpid)
+ return 1;
+#endif
+ return 0;
+}
+
+BTF_ID_LIST_SINGLE(btf_sched_entity_ids, struct, sched_entity)
+
+static const struct bpf_func_proto bpf_sched_entity_to_tgidpid_proto = {
+ .func = bpf_sched_entity_to_tgidpid,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_BTF_ID,
+ .arg1_btf_id = &btf_sched_entity_ids[0],
+};
+
+static const struct bpf_func_proto bpf_sched_entity_to_cgrpid_proto = {
+ .func = bpf_sched_entity_to_cgrpid,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_BTF_ID,
+ .arg1_btf_id = &btf_sched_entity_ids[0],
+};
+
+static const struct bpf_func_proto bpf_sched_entity_belongs_to_cgrp_proto = {
+ .func = bpf_sched_entity_belongs_to_cgrp,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_BTF_ID,
+ .arg1_btf_id = &btf_sched_entity_ids[0],
+ .arg2_type = ARG_ANYTHING,
+};
+
static const struct bpf_func_proto *
bpf_sched_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_trace_printk:
return bpf_get_trace_printk_proto();
+ case BPF_FUNC_sched_entity_to_tgidpid:
+ return &bpf_sched_entity_to_tgidpid_proto;
+ case BPF_FUNC_sched_entity_to_cgrpid:
+ return &bpf_sched_entity_to_cgrpid_proto;
+ case BPF_FUNC_sched_entity_belongs_to_cgrp:
+ return &bpf_sched_entity_belongs_to_cgrp_proto;
default:
return NULL;
}
diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
index 00ac7b79cddb..84019ba5b67b 100755
--- a/scripts/bpf_doc.py
+++ b/scripts/bpf_doc.py
@@ -548,6 +548,7 @@ class PrinterHelpers(Printer):
'struct socket',
'struct file',
'struct bpf_timer',
+ 'struct sched_entity',
]
known_types = {
'...',
@@ -596,6 +597,7 @@ class PrinterHelpers(Printer):
'struct socket',
'struct file',
'struct bpf_timer',
+ 'struct sched_entity',
}
mapped_types = {
'u8': '__u8',
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 6dfbebb8fc8f..199e4a92820d 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4900,6 +4900,26 @@ union bpf_attr {
* **-EINVAL** if *flags* is not zero.
*
* **-ENOENT** if architecture does not support branch records.
+ *
+ * u64 bpf_sched_entity_to_tgidpid(struct sched_entity *se)
+ * Description
+ * Return task's encoded tgid and pid if the sched entity is a task.
+ * Return
+ * Tgid and pid encoded as tgid << 32 \| pid, if *se* is a task. (u64)-1 otherwise.
+ *
+ * u64 bpf_sched_entity_to_cgrpid(struct sched_entity *se)
+ * Description
+ * Return cgroup id if the given sched entity is a cgroup.
+ * Return
+ * Cgroup id, if *se* is a cgroup. (u64)-1 otherwise.
+ *
+ * long bpf_sched_entity_belongs_to_cgrp(struct sched_entity *se, u64 cgrpid)
+ * Description
+ * Checks whether the sched entity belongs to a cgroup or
+ * it's sub-tree. It doesn't require a cgroup CPU controller
+ * to be enabled.
+ * Return
+ * 1 if the sched entity belongs to a cgroup, 0 otherwise.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5079,6 +5099,9 @@ union bpf_attr {
FN(get_attach_cookie), \
FN(task_pt_regs), \
FN(get_branch_snapshot), \
+ FN(sched_entity_to_tgidpid), \
+ FN(sched_entity_to_cgrpid), \
+ FN(sched_entity_belongs_to_cgrp), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.31.1
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