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Date: Wed, 21 Apr 2010 17:42:54 +0800
From: Lin Ming <ming.m.lin@...el.com>
To: "eranian@...il.com" <eranian@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
"Gary.Mohr@...l.com" <Gary.Mohr@...l.com>,
Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC] perf_events: support for uncore a.k.a. nest units
On Wed, 2010-04-21 at 16:44 +0800, stephane eranian wrote:
> On Wed, Apr 21, 2010 at 10:39 AM, Lin Ming <ming.m.lin@...el.com> wrote:
> > On Wed, 2010-04-21 at 16:32 +0800, stephane eranian wrote:
> >> Seems to me that struct pmu is a shared resource across all CPUs.
> >> I don't understand why scheduling on one CPU would have to impact
> >> all the other CPUs, unless I am missing something here.
> >
> > Do you mean the pmu->flag?
>
> Yes.
Thanks for the review.
Changes log:
v2.
pmu->flag should be per cpu (Stephane Eranian)
change definition of "const struct pmu" to "struct pmu" since it's not
read only now.
v1.
remove hw_perf_group_sched_in() based on Peter's idea.
---
arch/x86/kernel/cpu/perf_event.c | 183 ++++++++++++++------------------------
include/linux/perf_event.h | 16 +++-
kernel/perf_event.c | 55 ++++++------
3 files changed, 106 insertions(+), 148 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 626154a..1113fd5 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -598,7 +598,7 @@ static void x86_pmu_enable_all(int added)
}
}
-static const struct pmu pmu;
+static struct pmu pmu;
static inline int is_x86_event(struct perf_event *event)
{
@@ -935,6 +935,7 @@ static int x86_pmu_enable(struct perf_event *event)
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
struct hw_perf_event *hwc;
int assign[X86_PMC_IDX_MAX];
+ u8 *flag;
int n, n0, ret;
hwc = &event->hw;
@@ -944,6 +945,10 @@ static int x86_pmu_enable(struct perf_event *event)
if (n < 0)
return n;
+ flag = perf_pmu_flag((struct pmu *)event->pmu);
+ if (!(*flag & PERF_EVENT_TRAN_STARTED))
+ goto out;
+
ret = x86_pmu.schedule_events(cpuc, n, assign);
if (ret)
return ret;
@@ -953,6 +958,7 @@ static int x86_pmu_enable(struct perf_event *event)
*/
memcpy(cpuc->assign, assign, n*sizeof(int));
+out:
cpuc->n_events = n;
cpuc->n_added += n - n0;
@@ -1210,119 +1216,6 @@ x86_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
return &unconstrained;
}
-static int x86_event_sched_in(struct perf_event *event,
- struct perf_cpu_context *cpuctx)
-{
- int ret = 0;
-
- event->state = PERF_EVENT_STATE_ACTIVE;
- event->oncpu = smp_processor_id();
- event->tstamp_running += event->ctx->time - event->tstamp_stopped;
-
- if (!is_x86_event(event))
- ret = event->pmu->enable(event);
-
- if (!ret && !is_software_event(event))
- cpuctx->active_oncpu++;
-
- if (!ret && event->attr.exclusive)
- cpuctx->exclusive = 1;
-
- return ret;
-}
-
-static void x86_event_sched_out(struct perf_event *event,
- struct perf_cpu_context *cpuctx)
-{
- event->state = PERF_EVENT_STATE_INACTIVE;
- event->oncpu = -1;
-
- if (!is_x86_event(event))
- event->pmu->disable(event);
-
- event->tstamp_running -= event->ctx->time - event->tstamp_stopped;
-
- if (!is_software_event(event))
- cpuctx->active_oncpu--;
-
- if (event->attr.exclusive || !cpuctx->active_oncpu)
- cpuctx->exclusive = 0;
-}
-
-/*
- * Called to enable a whole group of events.
- * Returns 1 if the group was enabled, or -EAGAIN if it could not be.
- * Assumes the caller has disabled interrupts and has
- * frozen the PMU with hw_perf_save_disable.
- *
- * called with PMU disabled. If successful and return value 1,
- * then guaranteed to call perf_enable() and hw_perf_enable()
- */
-int hw_perf_group_sched_in(struct perf_event *leader,
- struct perf_cpu_context *cpuctx,
- struct perf_event_context *ctx)
-{
- struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
- struct perf_event *sub;
- int assign[X86_PMC_IDX_MAX];
- int n0, n1, ret;
-
- if (!x86_pmu_initialized())
- return 0;
-
- /* n0 = total number of events */
- n0 = collect_events(cpuc, leader, true);
- if (n0 < 0)
- return n0;
-
- ret = x86_pmu.schedule_events(cpuc, n0, assign);
- if (ret)
- return ret;
-
- ret = x86_event_sched_in(leader, cpuctx);
- if (ret)
- return ret;
-
- n1 = 1;
- list_for_each_entry(sub, &leader->sibling_list, group_entry) {
- if (sub->state > PERF_EVENT_STATE_OFF) {
- ret = x86_event_sched_in(sub, cpuctx);
- if (ret)
- goto undo;
- ++n1;
- }
- }
- /*
- * copy new assignment, now we know it is possible
- * will be used by hw_perf_enable()
- */
- memcpy(cpuc->assign, assign, n0*sizeof(int));
-
- cpuc->n_events = n0;
- cpuc->n_added += n1;
- ctx->nr_active += n1;
-
- /*
- * 1 means successful and events are active
- * This is not quite true because we defer
- * actual activation until hw_perf_enable() but
- * this way we* ensure caller won't try to enable
- * individual events
- */
- return 1;
-undo:
- x86_event_sched_out(leader, cpuctx);
- n0 = 1;
- list_for_each_entry(sub, &leader->sibling_list, group_entry) {
- if (sub->state == PERF_EVENT_STATE_ACTIVE) {
- x86_event_sched_out(sub, cpuctx);
- if (++n0 == n1)
- break;
- }
- }
- return ret;
-}
-
#include "perf_event_amd.c"
#include "perf_event_p6.c"
#include "perf_event_p4.c"
@@ -1397,6 +1290,14 @@ void __init init_hw_perf_events(void)
return;
}
+ /*
+ * TBD: will move this to pmu register function
+ * when multiple hw pmu support is added
+ */
+ pmu.flag = alloc_percpu(u8);
+ if (!pmu.flag)
+ return;
+
pmu_check_apic();
pr_cont("%s PMU driver.\n", x86_pmu.name);
@@ -1454,13 +1355,61 @@ static inline void x86_pmu_read(struct perf_event *event)
x86_perf_event_update(event);
}
-static const struct pmu pmu = {
+/*
+ * Set the flag to make pmu::enable() not perform the
+ * schedulablilty test.
+ */
+static void x86_pmu_start_txn(struct pmu *pmu)
+{
+ u8 *flag = perf_pmu_flag(pmu);
+
+ *flag |= PERF_EVENT_TRAN_STARTED;
+}
+
+static void x86_pmu_stop_txn(struct pmu *pmu)
+{
+ u8 *flag = perf_pmu_flag(pmu);
+
+ *flag &= ~PERF_EVENT_TRAN_STARTED;
+}
+
+/*
+ * Return 0 if commit transaction success
+ */
+static int x86_pmu_commit_txn(struct pmu *pmu)
+{
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ int assign[X86_PMC_IDX_MAX];
+ int n, ret;
+
+ n = cpuc->n_events;
+
+ if (!x86_pmu_initialized())
+ return -EAGAIN;
+
+ ret = x86_pmu.schedule_events(cpuc, n, assign);
+ if (ret)
+ return ret;
+
+ /*
+ * copy new assignment, now we know it is possible
+ * will be used by hw_perf_enable()
+ */
+ memcpy(cpuc->assign, assign, n*sizeof(int));
+
+ return 0;
+}
+
+static struct pmu pmu = {
.enable = x86_pmu_enable,
.disable = x86_pmu_disable,
.start = x86_pmu_start,
.stop = x86_pmu_stop,
.read = x86_pmu_read,
.unthrottle = x86_pmu_unthrottle,
+ .start_txn = x86_pmu_start_txn,
+ .stop_txn = x86_pmu_stop_txn,
+ .commit_txn = x86_pmu_commit_txn,
};
/*
@@ -1537,9 +1486,9 @@ out:
return ret;
}
-const struct pmu *hw_perf_event_init(struct perf_event *event)
+struct pmu *hw_perf_event_init(struct perf_event *event)
{
- const struct pmu *tmp;
+ struct pmu *tmp;
int err;
err = __hw_perf_event_init(event);
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index bf896d0..9fa3f46 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -524,6 +524,8 @@ struct hw_perf_event {
struct perf_event;
+#define PERF_EVENT_TRAN_STARTED 1
+
/**
* struct pmu - generic performance monitoring unit
*/
@@ -534,6 +536,12 @@ struct pmu {
void (*stop) (struct perf_event *event);
void (*read) (struct perf_event *event);
void (*unthrottle) (struct perf_event *event);
+ void (*start_txn) (struct pmu *pmu);
+ void (*stop_txn) (struct pmu *pmu);
+ int (*commit_txn) (struct pmu *pmu);
+
+ /* percpu flag */
+ u8 *flag;
};
/**
@@ -610,7 +618,7 @@ struct perf_event {
int group_flags;
struct perf_event *group_leader;
struct perf_event *output;
- const struct pmu *pmu;
+ struct pmu *pmu;
enum perf_event_active_state state;
atomic64_t count;
@@ -782,7 +790,7 @@ struct perf_output_handle {
*/
extern int perf_max_events;
-extern const struct pmu *hw_perf_event_init(struct perf_event *event);
+extern struct pmu *hw_perf_event_init(struct perf_event *event);
extern void perf_event_task_sched_in(struct task_struct *task);
extern void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next);
@@ -799,9 +807,6 @@ extern void perf_disable(void);
extern void perf_enable(void);
extern int perf_event_task_disable(void);
extern int perf_event_task_enable(void);
-extern int hw_perf_group_sched_in(struct perf_event *group_leader,
- struct perf_cpu_context *cpuctx,
- struct perf_event_context *ctx);
extern void perf_event_update_userpage(struct perf_event *event);
extern int perf_event_release_kernel(struct perf_event *event);
extern struct perf_event *
@@ -811,6 +816,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr,
perf_overflow_handler_t callback);
extern u64 perf_event_read_value(struct perf_event *event,
u64 *enabled, u64 *running);
+extern u8 *perf_pmu_flag(struct pmu *pmu);
struct perf_sample_data {
u64 type;
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 07b7a43..4820090 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -75,7 +75,7 @@ static DEFINE_SPINLOCK(perf_resource_lock);
/*
* Architecture provided APIs - weak aliases:
*/
-extern __weak const struct pmu *hw_perf_event_init(struct perf_event *event)
+extern __weak struct pmu *hw_perf_event_init(struct perf_event *event)
{
return NULL;
}
@@ -83,15 +83,14 @@ extern __weak const struct pmu *hw_perf_event_init(struct perf_event *event)
void __weak hw_perf_disable(void) { barrier(); }
void __weak hw_perf_enable(void) { barrier(); }
-int __weak
-hw_perf_group_sched_in(struct perf_event *group_leader,
- struct perf_cpu_context *cpuctx,
- struct perf_event_context *ctx)
+void __weak perf_event_print_debug(void) { }
+
+u8 *perf_pmu_flag(struct pmu *pmu)
{
- return 0;
-}
+ int cpu = smp_processor_id();
-void __weak perf_event_print_debug(void) { }
+ return per_cpu_ptr(pmu->flag, cpu);
+}
static DEFINE_PER_CPU(int, perf_disable_count);
@@ -642,14 +641,13 @@ group_sched_in(struct perf_event *group_event,
struct perf_event_context *ctx)
{
struct perf_event *event, *partial_group;
+ struct pmu *pmu = group_event->pmu;
int ret;
if (group_event->state == PERF_EVENT_STATE_OFF)
return 0;
- ret = hw_perf_group_sched_in(group_event, cpuctx, ctx);
- if (ret)
- return ret < 0 ? ret : 0;
+ pmu->start_txn(pmu);
if (event_sched_in(group_event, cpuctx, ctx))
return -EAGAIN;
@@ -664,16 +662,21 @@ group_sched_in(struct perf_event *group_event,
}
}
- return 0;
+ ret = pmu->commit_txn(pmu);
+ if (!ret) {
+ pmu->stop_txn(pmu);
+ return 0;
+ }
group_error:
+ pmu->stop_txn(pmu);
+
/*
- * Groups can be scheduled in as one unit only, so undo any
- * partial group before returning:
+ * Commit transaction fails, rollback
+ * Groups can be scheduled in as one unit only, so undo
+ * whole group before returning:
*/
list_for_each_entry(event, &group_event->sibling_list, group_entry) {
- if (event == partial_group)
- break;
event_sched_out(event, cpuctx, ctx);
}
event_sched_out(group_event, cpuctx, ctx);
@@ -4139,7 +4142,7 @@ static void perf_swevent_disable(struct perf_event *event)
hlist_del_rcu(&event->hlist_entry);
}
-static const struct pmu perf_ops_generic = {
+static struct pmu perf_ops_generic = {
.enable = perf_swevent_enable,
.disable = perf_swevent_disable,
.read = perf_swevent_read,
@@ -4250,7 +4253,7 @@ static void cpu_clock_perf_event_read(struct perf_event *event)
cpu_clock_perf_event_update(event);
}
-static const struct pmu perf_ops_cpu_clock = {
+static struct pmu perf_ops_cpu_clock = {
.enable = cpu_clock_perf_event_enable,
.disable = cpu_clock_perf_event_disable,
.read = cpu_clock_perf_event_read,
@@ -4307,7 +4310,7 @@ static void task_clock_perf_event_read(struct perf_event *event)
task_clock_perf_event_update(event, time);
}
-static const struct pmu perf_ops_task_clock = {
+static struct pmu perf_ops_task_clock = {
.enable = task_clock_perf_event_enable,
.disable = task_clock_perf_event_disable,
.read = task_clock_perf_event_read,
@@ -4448,7 +4451,7 @@ static void tp_perf_event_destroy(struct perf_event *event)
swevent_hlist_put(event);
}
-static const struct pmu *tp_perf_event_init(struct perf_event *event)
+static struct pmu *tp_perf_event_init(struct perf_event *event)
{
int err;
@@ -4505,7 +4508,7 @@ static int perf_tp_event_match(struct perf_event *event,
return 1;
}
-static const struct pmu *tp_perf_event_init(struct perf_event *event)
+static struct pmu *tp_perf_event_init(struct perf_event *event)
{
return NULL;
}
@@ -4527,7 +4530,7 @@ static void bp_perf_event_destroy(struct perf_event *event)
release_bp_slot(event);
}
-static const struct pmu *bp_perf_event_init(struct perf_event *bp)
+static struct pmu *bp_perf_event_init(struct perf_event *bp)
{
int err;
@@ -4551,7 +4554,7 @@ void perf_bp_event(struct perf_event *bp, void *data)
perf_swevent_add(bp, 1, 1, &sample, regs);
}
#else
-static const struct pmu *bp_perf_event_init(struct perf_event *bp)
+static struct pmu *bp_perf_event_init(struct perf_event *bp)
{
return NULL;
}
@@ -4573,9 +4576,9 @@ static void sw_perf_event_destroy(struct perf_event *event)
swevent_hlist_put(event);
}
-static const struct pmu *sw_perf_event_init(struct perf_event *event)
+static struct pmu *sw_perf_event_init(struct perf_event *event)
{
- const struct pmu *pmu = NULL;
+ struct pmu *pmu = NULL;
u64 event_id = event->attr.config;
/*
@@ -4637,7 +4640,7 @@ perf_event_alloc(struct perf_event_attr *attr,
perf_overflow_handler_t overflow_handler,
gfp_t gfpflags)
{
- const struct pmu *pmu;
+ struct pmu *pmu;
struct perf_event *event;
struct hw_perf_event *hwc;
long err;
>
> > You are right, pmu->flag should be per cpu data.
> >
> > Will update the patch.
> >
> > Thanks,
> > Lin Ming
> >
> >>
--
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