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Message-ID: <20231009210425.GC6307@noisy.programming.kicks-ass.net>
Date: Mon, 9 Oct 2023 23:04:25 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
Stephane Eranian <eranian@...gle.com>,
Kan Liang <kan.liang@...ux.intel.com>,
Ravi Bangoria <ravi.bangoria@....com>, stable@...r.kernel.org
Subject: Re: [PATCH] perf/core: Introduce cpuctx->cgrp_ctx_list
On Wed, Oct 04, 2023 at 09:32:24AM -0700, Namhyung Kim wrote:
> Yeah, I know.. but I couldn't come up with a better solution.
Not been near a compiler, and haven't fully thought it through, but
could something like the work work?
---
include/linux/perf_event.h | 1 +
kernel/events/core.c | 115 +++++++++++++++++++++++----------------------
2 files changed, 61 insertions(+), 55 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f31f962a6445..0367d748fae0 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -878,6 +878,7 @@ struct perf_event_pmu_context {
unsigned int embedded : 1;
unsigned int nr_events;
+ unsigned int nr_cgroups;
atomic_t refcount; /* event <-> epc */
struct rcu_head rcu_head;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 708d474c2ede..f3d5d47ecdfc 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -375,6 +375,7 @@ enum event_type_t {
EVENT_TIME = 0x4,
/* see ctx_resched() for details */
EVENT_CPU = 0x8,
+ EVENT_CGROUP = 0x10,
EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
};
@@ -684,20 +685,26 @@ do { \
___p; \
})
-static void perf_ctx_disable(struct perf_event_context *ctx)
+static void perf_ctx_disable(struct perf_event_context *ctx, bool cgroup)
{
struct perf_event_pmu_context *pmu_ctx;
- list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry)
+ list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
+ if (cgroup && !pmu_ctx->nr_cgroups)
+ continue;
perf_pmu_disable(pmu_ctx->pmu);
+ }
}
-static void perf_ctx_enable(struct perf_event_context *ctx)
+static void perf_ctx_enable(struct perf_event_context *ctx. bool cgroup)
{
struct perf_event_pmu_context *pmu_ctx;
- list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry)
+ list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
+ if (cgroup && !pmu_ctx->nr_cgroups)
+ continue;
perf_pmu_enable(pmu_ctx->pmu);
+ }
}
static void ctx_sched_out(struct perf_event_context *ctx, enum event_type_t event_type);
@@ -856,9 +863,9 @@ static void perf_cgroup_switch(struct task_struct *task)
return;
perf_ctx_lock(cpuctx, cpuctx->task_ctx);
- perf_ctx_disable(&cpuctx->ctx);
+ perf_ctx_disable(&cpuctx->ctx, true);
- ctx_sched_out(&cpuctx->ctx, EVENT_ALL);
+ ctx_sched_out(&cpuctx->ctx, EVENT_ALL|EVENT_CGROUP);
/*
* must not be done before ctxswout due
* to update_cgrp_time_from_cpuctx() in
@@ -870,9 +877,9 @@ static void perf_cgroup_switch(struct task_struct *task)
* perf_cgroup_set_timestamp() in ctx_sched_in()
* to not have to pass task around
*/
- ctx_sched_in(&cpuctx->ctx, EVENT_ALL);
+ ctx_sched_in(&cpuctx->ctx, EVENT_ALL|EVENT_CGROUP);
- perf_ctx_enable(&cpuctx->ctx);
+ perf_ctx_enable(&cpuctx->ctx, true);
perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
}
@@ -965,6 +972,8 @@ perf_cgroup_event_enable(struct perf_event *event, struct perf_event_context *ct
if (!is_cgroup_event(event))
return;
+ event->pmu_ctx->nr_cgroups++;
+
/*
* Because cgroup events are always per-cpu events,
* @ctx == &cpuctx->ctx.
@@ -985,6 +994,8 @@ perf_cgroup_event_disable(struct perf_event *event, struct perf_event_context *c
if (!is_cgroup_event(event))
return;
+ event->pmu_ctx->nr_cgroups--;
+
/*
* Because cgroup events are always per-cpu events,
* @ctx == &cpuctx->ctx.
@@ -2677,9 +2688,9 @@ static void ctx_resched(struct perf_cpu_context *cpuctx,
event_type &= EVENT_ALL;
- perf_ctx_disable(&cpuctx->ctx);
+ perf_ctx_disable(&cpuctx->ctx, false);
if (task_ctx) {
- perf_ctx_disable(task_ctx);
+ perf_ctx_disable(task_ctx, false);
task_ctx_sched_out(task_ctx, event_type);
}
@@ -2697,9 +2708,9 @@ static void ctx_resched(struct perf_cpu_context *cpuctx,
perf_event_sched_in(cpuctx, task_ctx);
- perf_ctx_enable(&cpuctx->ctx);
+ perf_ctx_enable(&cpuctx->ctx, false);
if (task_ctx)
- perf_ctx_enable(task_ctx);
+ perf_ctx_enable(task_ctx, false);
}
void perf_pmu_resched(struct pmu *pmu)
@@ -3244,6 +3255,9 @@ ctx_sched_out(struct perf_event_context *ctx, enum event_type_t event_type)
struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
struct perf_event_pmu_context *pmu_ctx;
int is_active = ctx->is_active;
+ bool cgroup = event_type & EVENT_CGROUP;
+
+ event_type &= ~EVENT_CGROUP;
lockdep_assert_held(&ctx->lock);
@@ -3290,8 +3304,11 @@ ctx_sched_out(struct perf_event_context *ctx, enum event_type_t event_type)
is_active ^= ctx->is_active; /* changed bits */
- list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry)
+ list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
+ if (cgroup && !pmu_ctx->nr_cgroups)
+ continue;
__pmu_ctx_sched_out(pmu_ctx, is_active);
+ }
}
/*
@@ -3482,7 +3499,7 @@ perf_event_context_sched_out(struct task_struct *task, struct task_struct *next)
raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
if (context_equiv(ctx, next_ctx)) {
- perf_ctx_disable(ctx);
+ perf_ctx_disable(ctx, false);
/* PMIs are disabled; ctx->nr_pending is stable. */
if (local_read(&ctx->nr_pending) ||
@@ -3502,7 +3519,7 @@ perf_event_context_sched_out(struct task_struct *task, struct task_struct *next)
perf_ctx_sched_task_cb(ctx, false);
perf_event_swap_task_ctx_data(ctx, next_ctx);
- perf_ctx_enable(ctx);
+ perf_ctx_enable(ctx, false);
/*
* RCU_INIT_POINTER here is safe because we've not
@@ -3526,13 +3543,13 @@ perf_event_context_sched_out(struct task_struct *task, struct task_struct *next)
if (do_switch) {
raw_spin_lock(&ctx->lock);
- perf_ctx_disable(ctx);
+ perf_ctx_disable(ctx, false);
inside_switch:
perf_ctx_sched_task_cb(ctx, false);
task_ctx_sched_out(ctx, EVENT_ALL);
- perf_ctx_enable(ctx);
+ perf_ctx_enable(ctx, false);
raw_spin_unlock(&ctx->lock);
}
}
@@ -3818,47 +3835,32 @@ static int merge_sched_in(struct perf_event *event, void *data)
return 0;
}
-static void ctx_pinned_sched_in(struct perf_event_context *ctx, struct pmu *pmu)
+static void pmu_groups_sched_in(struct perf_event_context *ctx,
+ struct perf_event_groups *groups,
+ struct pmu *pmu)
{
- struct perf_event_pmu_context *pmu_ctx;
int can_add_hw = 1;
-
- if (pmu) {
- visit_groups_merge(ctx, &ctx->pinned_groups,
- smp_processor_id(), pmu,
- merge_sched_in, &can_add_hw);
- } else {
- list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
- can_add_hw = 1;
- visit_groups_merge(ctx, &ctx->pinned_groups,
- smp_processor_id(), pmu_ctx->pmu,
- merge_sched_in, &can_add_hw);
- }
- }
+ visit_groups_merge(ctx, groups, smp_processor_id(), pmu,
+ merge_sched_in, &can_add_hw);
}
-static void ctx_flexible_sched_in(struct perf_event_context *ctx, struct pmu *pmu)
+static void ctx_groups_sched_in(struct perf_event_context *ctx,
+ struct perf_event_groups *groups,
+ bool cgroup)
{
struct perf_event_pmu_context *pmu_ctx;
- int can_add_hw = 1;
- if (pmu) {
- visit_groups_merge(ctx, &ctx->flexible_groups,
- smp_processor_id(), pmu,
- merge_sched_in, &can_add_hw);
- } else {
- list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
- can_add_hw = 1;
- visit_groups_merge(ctx, &ctx->flexible_groups,
- smp_processor_id(), pmu_ctx->pmu,
- merge_sched_in, &can_add_hw);
- }
+ list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
+ if (cgroup && !pmu_ctx->nr_cgroups)
+ continue;
+ pmu_groups_sched_in(ctx, groups, pmu_ctx->pmu);
}
}
-static void __pmu_ctx_sched_in(struct perf_event_context *ctx, struct pmu *pmu)
+static void __pmu_ctx_sched_in(struct perf_event_context *ctx,
+ struct pmu *pmu)
{
- ctx_flexible_sched_in(ctx, pmu);
+ pmu_groups_sched_in(ctx, &ctx->flexible_groups, pmu);
}
static void
@@ -3866,6 +3868,9 @@ ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type)
{
struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
int is_active = ctx->is_active;
+ bool cgroup = event_type & EVENT_CGROUP;
+
+ event_type &= ~EVENT_CGROUP;
lockdep_assert_held(&ctx->lock);
@@ -3898,11 +3903,11 @@ ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type)
* in order to give them the best chance of going on.
*/
if (is_active & EVENT_PINNED)
- ctx_pinned_sched_in(ctx, NULL);
+ ctx_groups_sched_in(ctx, &ctx->pinned_groups, cgroup);
/* Then walk through the lower prio flexible groups */
if (is_active & EVENT_FLEXIBLE)
- ctx_flexible_sched_in(ctx, NULL);
+ ctx_groups_sched_in(ctx, &ctx->flexible_groups, cgroup);
}
static void perf_event_context_sched_in(struct task_struct *task)
@@ -3917,11 +3922,11 @@ static void perf_event_context_sched_in(struct task_struct *task)
if (cpuctx->task_ctx == ctx) {
perf_ctx_lock(cpuctx, ctx);
- perf_ctx_disable(ctx);
+ perf_ctx_disable(ctx, false);
perf_ctx_sched_task_cb(ctx, true);
- perf_ctx_enable(ctx);
+ perf_ctx_enable(ctx, false);
perf_ctx_unlock(cpuctx, ctx);
goto rcu_unlock;
}
@@ -3934,7 +3939,7 @@ static void perf_event_context_sched_in(struct task_struct *task)
if (!ctx->nr_events)
goto unlock;
- perf_ctx_disable(ctx);
+ perf_ctx_disable(ctx, false);
/*
* We want to keep the following priority order:
* cpu pinned (that don't need to move), task pinned,
@@ -3944,7 +3949,7 @@ static void perf_event_context_sched_in(struct task_struct *task)
* events, no need to flip the cpuctx's events around.
*/
if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree)) {
- perf_ctx_disable(&cpuctx->ctx);
+ perf_ctx_disable(&cpuctx->ctx, false);
ctx_sched_out(&cpuctx->ctx, EVENT_FLEXIBLE);
}
@@ -3953,9 +3958,9 @@ static void perf_event_context_sched_in(struct task_struct *task)
perf_ctx_sched_task_cb(cpuctx->task_ctx, true);
if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree))
- perf_ctx_enable(&cpuctx->ctx);
+ perf_ctx_enable(&cpuctx->ctx, false);
- perf_ctx_enable(ctx);
+ perf_ctx_enable(ctx, false);
unlock:
perf_ctx_unlock(cpuctx, ctx);
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