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Subject[tip:perfcounters/urgent] perf: Rework/fix the whole read vs group stuff
Commit-ID:  3dab77fb1bf89664bb1c9544607159dcab6f7d57
Gitweb: http://git.kernel.org/tip/3dab77fb1bf89664bb1c9544607159dcab6f7d57
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 13 Aug 2009 11:47:53 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 13 Aug 2009 12:58:04 +0200

perf: Rework/fix the whole read vs group stuff

Replace PERF_SAMPLE_GROUP with PERF_SAMPLE_READ and introduce
PERF_FORMAT_GROUP to deal with group reads in a more generic
way.

This allows you to get group reads out of read() as well.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey J Ashford <cjashfor@us.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
LKML-Reference: <20090813103655.117411814@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
include/linux/perf_counter.h | 47 ++++++--
kernel/perf_counter.c | 274 +++++++++++++++++++++++++++++++-----------
2 files changed, 238 insertions(+), 83 deletions(-)
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 2b36afe..b53f700 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -115,7 +115,7 @@ enum perf_counter_sample_format {
PERF_SAMPLE_TID = 1U << 1,
PERF_SAMPLE_TIME = 1U << 2,
PERF_SAMPLE_ADDR = 1U << 3,
- PERF_SAMPLE_GROUP = 1U << 4,
+ PERF_SAMPLE_READ = 1U << 4,
PERF_SAMPLE_CALLCHAIN = 1U << 5,
PERF_SAMPLE_ID = 1U << 6,
PERF_SAMPLE_CPU = 1U << 7,
@@ -127,16 +127,32 @@ enum perf_counter_sample_format {
};

/*
- * Bits that can be set in attr.read_format to request that
- * reads on the counter should return the indicated quantities,
- * in increasing order of bit value, after the counter value.
+ * The format of the data returned by read() on a perf counter fd,
+ * as specified by attr.read_format:
+ *
+ * struct read_format {
+ * { u64 value;
+ * { u64 time_enabled; } && PERF_FORMAT_ENABLED
+ * { u64 time_running; } && PERF_FORMAT_RUNNING
+ * { u64 id; } && PERF_FORMAT_ID
+ * } && !PERF_FORMAT_GROUP
+ *
+ * { u64 nr;
+ * { u64 time_enabled; } && PERF_FORMAT_ENABLED
+ * { u64 time_running; } && PERF_FORMAT_RUNNING
+ * { u64 value;
+ * { u64 id; } && PERF_FORMAT_ID
+ * } cntr[nr];
+ * } && PERF_FORMAT_GROUP
+ * };
*/
enum perf_counter_read_format {
PERF_FORMAT_TOTAL_TIME_ENABLED = 1U << 0,
PERF_FORMAT_TOTAL_TIME_RUNNING = 1U << 1,
PERF_FORMAT_ID = 1U << 2,
+ PERF_FORMAT_GROUP = 1U << 3,

- PERF_FORMAT_MAX = 1U << 3, /* non-ABI */
+ PERF_FORMAT_MAX = 1U << 4, /* non-ABI */
};

#define PERF_ATTR_SIZE_VER0 64 /* sizeof first published struct */
@@ -343,10 +359,8 @@ enum perf_event_type {
* struct {
* struct perf_event_header header;
* u32 pid, tid;
- * u64 value;
- * { u64 time_enabled; } && PERF_FORMAT_ENABLED
- * { u64 time_running; } && PERF_FORMAT_RUNNING
- * { u64 parent_id; } && PERF_FORMAT_ID
+ *
+ * struct read_format values;
* };
*/
PERF_EVENT_READ = 8,
@@ -364,11 +378,22 @@ enum perf_event_type {
* { u32 cpu, res; } && PERF_SAMPLE_CPU
* { u64 period; } && PERF_SAMPLE_PERIOD
*
- * { u64 nr;
- * { u64 id, val; } cnt[nr]; } && PERF_SAMPLE_GROUP
+ * { struct read_format values; } && PERF_SAMPLE_READ
*
* { u64 nr,
* u64 ips[nr]; } && PERF_SAMPLE_CALLCHAIN
+ *
+ * #
+ * # The RAW record below is opaque data wrt the ABI
+ * #
+ * # That is, the ABI doesn't make any promises wrt to
+ * # the stability of its content, it may vary depending
+ * # on event, hardware, kernel version and phase of
+ * # the moon.
+ * #
+ * # In other words, PERF_SAMPLE_RAW contents are not an ABI.
+ * #
+ *
* { u32 size;
* char data[size];}&& PERF_SAMPLE_RAW
* };
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 3dd4339..b8c6b97 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1692,7 +1692,32 @@ static int perf_release(struct inode *inode, struct file *file)
return 0;
}

-static u64 perf_counter_read_tree(struct perf_counter *counter)
+static int perf_counter_read_size(struct perf_counter *counter)
+{
+ int entry = sizeof(u64); /* value */
+ int size = 0;
+ int nr = 1;
+
+ if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+ size += sizeof(u64);
+
+ if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+ size += sizeof(u64);
+
+ if (counter->attr.read_format & PERF_FORMAT_ID)
+ entry += sizeof(u64);
+
+ if (counter->attr.read_format & PERF_FORMAT_GROUP) {
+ nr += counter->group_leader->nr_siblings;
+ size += sizeof(u64);
+ }
+
+ size += entry * nr;
+
+ return size;
+}
+
+static u64 perf_counter_read_value(struct perf_counter *counter)
{
struct perf_counter *child;
u64 total = 0;
@@ -1704,14 +1729,96 @@ static u64 perf_counter_read_tree(struct perf_counter *counter)
return total;
}

+static int perf_counter_read_entry(struct perf_counter *counter,
+ u64 read_format, char __user *buf)
+{
+ int n = 0, count = 0;
+ u64 values[2];
+
+ values[n++] = perf_counter_read_value(counter);
+ if (read_format & PERF_FORMAT_ID)
+ values[n++] = primary_counter_id(counter);
+
+ count = n * sizeof(u64);
+
+ if (copy_to_user(buf, values, count))
+ return -EFAULT;
+
+ return count;
+}
+
+static int perf_counter_read_group(struct perf_counter *counter,
+ u64 read_format, char __user *buf)
+{
+ struct perf_counter *leader = counter->group_leader, *sub;
+ int n = 0, size = 0, err = -EFAULT;
+ u64 values[3];
+
+ values[n++] = 1 + leader->nr_siblings;
+ if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+ values[n++] = leader->total_time_enabled +
+ atomic64_read(&leader->child_total_time_enabled);
+ }
+ if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+ values[n++] = leader->total_time_running +
+ atomic64_read(&leader->child_total_time_running);
+ }
+
+ size = n * sizeof(u64);
+
+ if (copy_to_user(buf, values, size))
+ return -EFAULT;
+
+ err = perf_counter_read_entry(leader, read_format, buf + size);
+ if (err < 0)
+ return err;
+
+ size += err;
+
+ list_for_each_entry(sub, &leader->sibling_list, list_entry) {
+ err = perf_counter_read_entry(counter, read_format,
+ buf + size);
+ if (err < 0)
+ return err;
+
+ size += err;
+ }
+
+ return size;
+}
+
+static int perf_counter_read_one(struct perf_counter *counter,
+ u64 read_format, char __user *buf)
+{
+ u64 values[4];
+ int n = 0;
+
+ values[n++] = perf_counter_read_value(counter);
+ if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+ values[n++] = counter->total_time_enabled +
+ atomic64_read(&counter->child_total_time_enabled);
+ }
+ if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+ values[n++] = counter->total_time_running +
+ atomic64_read(&counter->child_total_time_running);
+ }
+ if (read_format & PERF_FORMAT_ID)
+ values[n++] = primary_counter_id(counter);
+
+ if (copy_to_user(buf, values, n * sizeof(u64)))
+ return -EFAULT;
+
+ return n * sizeof(u64);
+}
+
/*
* Read the performance counter - simple non blocking version for now
*/
static ssize_t
perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
{
- u64 values[4];
- int n;
+ u64 read_format = counter->attr.read_format;
+ int ret;

/*
* Return end-of-file for a read on a counter that is in
@@ -1721,28 +1828,18 @@ perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
if (counter->state == PERF_COUNTER_STATE_ERROR)
return 0;

+ if (count < perf_counter_read_size(counter))
+ return -ENOSPC;
+
WARN_ON_ONCE(counter->ctx->parent_ctx);
mutex_lock(&counter->child_mutex);
- values[0] = perf_counter_read_tree(counter);
- n = 1;
- if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
- values[n++] = counter->total_time_enabled +
- atomic64_read(&counter->child_total_time_enabled);
- if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
- values[n++] = counter->total_time_running +
- atomic64_read(&counter->child_total_time_running);
- if (counter->attr.read_format & PERF_FORMAT_ID)
- values[n++] = primary_counter_id(counter);
+ if (read_format & PERF_FORMAT_GROUP)
+ ret = perf_counter_read_group(counter, read_format, buf);
+ else
+ ret = perf_counter_read_one(counter, read_format, buf);
mutex_unlock(&counter->child_mutex);

- if (count < n * sizeof(u64))
- return -EINVAL;
- count = n * sizeof(u64);
-
- if (copy_to_user(buf, values, count))
- return -EFAULT;
-
- return count;
+ return ret;
}

static ssize_t
@@ -2631,6 +2728,79 @@ static u32 perf_counter_tid(struct perf_counter *counter, struct task_struct *p)
return task_pid_nr_ns(p, counter->ns);
}

+static void perf_output_read_one(struct perf_output_handle *handle,
+ struct perf_counter *counter)
+{
+ u64 read_format = counter->attr.read_format;
+ u64 values[4];
+ int n = 0;
+
+ values[n++] = atomic64_read(&counter->count);
+ if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+ values[n++] = counter->total_time_enabled +
+ atomic64_read(&counter->child_total_time_enabled);
+ }
+ if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+ values[n++] = counter->total_time_running +
+ atomic64_read(&counter->child_total_time_running);
+ }
+ if (read_format & PERF_FORMAT_ID)
+ values[n++] = primary_counter_id(counter);
+
+ perf_output_copy(handle, values, n * sizeof(u64));
+}
+
+/*
+ * XXX PERF_FORMAT_GROUP vs inherited counters seems difficult.
+ */
+static void perf_output_read_group(struct perf_output_handle *handle,
+ struct perf_counter *counter)
+{
+ struct perf_counter *leader = counter->group_leader, *sub;
+ u64 read_format = counter->attr.read_format;
+ u64 values[5];
+ int n = 0;
+
+ values[n++] = 1 + leader->nr_siblings;
+
+ if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+ values[n++] = leader->total_time_enabled;
+
+ if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+ values[n++] = leader->total_time_running;
+
+ if (leader != counter)
+ leader->pmu->read(leader);
+
+ values[n++] = atomic64_read(&leader->count);
+ if (read_format & PERF_FORMAT_ID)
+ values[n++] = primary_counter_id(leader);
+
+ perf_output_copy(handle, values, n * sizeof(u64));
+
+ list_for_each_entry(sub, &leader->sibling_list, list_entry) {
+ n = 0;
+
+ if (sub != counter)
+ sub->pmu->read(sub);
+
+ values[n++] = atomic64_read(&sub->count);
+ if (read_format & PERF_FORMAT_ID)
+ values[n++] = primary_counter_id(sub);
+
+ perf_output_copy(handle, values, n * sizeof(u64));
+ }
+}
+
+static void perf_output_read(struct perf_output_handle *handle,
+ struct perf_counter *counter)
+{
+ if (counter->attr.read_format & PERF_FORMAT_GROUP)
+ perf_output_read_group(handle, counter);
+ else
+ perf_output_read_one(handle, counter);
+}
+
void perf_counter_output(struct perf_counter *counter, int nmi,
struct perf_sample_data *data)
{
@@ -2642,10 +2812,6 @@ void perf_counter_output(struct perf_counter *counter, int nmi,
struct {
u32 pid, tid;
} tid_entry;
- struct {
- u64 id;
- u64 counter;
- } group_entry;
struct perf_callchain_entry *callchain = NULL;
int callchain_size = 0;
u64 time;
@@ -2700,10 +2866,8 @@ void perf_counter_output(struct perf_counter *counter, int nmi,
if (sample_type & PERF_SAMPLE_PERIOD)
header.size += sizeof(u64);

- if (sample_type & PERF_SAMPLE_GROUP) {
- header.size += sizeof(u64) +
- counter->nr_siblings * sizeof(group_entry);
- }
+ if (sample_type & PERF_SAMPLE_READ)
+ header.size += perf_counter_read_size(counter);

if (sample_type & PERF_SAMPLE_CALLCHAIN) {
callchain = perf_callchain(data->regs);
@@ -2760,26 +2924,8 @@ void perf_counter_output(struct perf_counter *counter, int nmi,
if (sample_type & PERF_SAMPLE_PERIOD)
perf_output_put(&handle, data->period);

- /*
- * XXX PERF_SAMPLE_GROUP vs inherited counters seems difficult.
- */
- if (sample_type & PERF_SAMPLE_GROUP) {
- struct perf_counter *leader, *sub;
- u64 nr = counter->nr_siblings;
-
- perf_output_put(&handle, nr);
-
- leader = counter->group_leader;
- list_for_each_entry(sub, &leader->sibling_list, list_entry) {
- if (sub != counter)
- sub->pmu->read(sub);
-
- group_entry.id = primary_counter_id(sub);
- group_entry.counter = atomic64_read(&sub->count);
-
- perf_output_put(&handle, group_entry);
- }
- }
+ if (sample_type & PERF_SAMPLE_READ)
+ perf_output_read(&handle, counter);

if (sample_type & PERF_SAMPLE_CALLCHAIN) {
if (callchain)
@@ -2818,8 +2964,6 @@ struct perf_read_event {

u32 pid;
u32 tid;
- u64 value;
- u64 format[3];
};

static void
@@ -2831,34 +2975,20 @@ perf_counter_read_event(struct perf_counter *counter,
.header = {
.type = PERF_EVENT_READ,
.misc = 0,
- .size = sizeof(event) - sizeof(event.format),
+ .size = sizeof(event) + perf_counter_read_size(counter),
},
.pid = perf_counter_pid(counter, task),
.tid = perf_counter_tid(counter, task),
- .value = atomic64_read(&counter->count),
};
- int ret, i = 0;
-
- if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
- event.header.size += sizeof(u64);
- event.format[i++] = counter->total_time_enabled;
- }
-
- if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
- event.header.size += sizeof(u64);
- event.format[i++] = counter->total_time_running;
- }
-
- if (counter->attr.read_format & PERF_FORMAT_ID) {
- event.header.size += sizeof(u64);
- event.format[i++] = primary_counter_id(counter);
- }
+ int ret;

ret = perf_output_begin(&handle, counter, event.header.size, 0, 0);
if (ret)
return;

- perf_output_copy(&handle, &event, event.header.size);
+ perf_output_put(&handle, event);
+ perf_output_read(&handle, counter);
+
perf_output_end(&handle);
}

@@ -3921,9 +4051,9 @@ perf_counter_alloc(struct perf_counter_attr *attr,
atomic64_set(&hwc->period_left, hwc->sample_period);

/*
- * we currently do not support PERF_SAMPLE_GROUP on inherited counters
+ * we currently do not support PERF_FORMAT_GROUP on inherited counters
*/
- if (attr->inherit && (attr->sample_type & PERF_SAMPLE_GROUP))
+ if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
goto done;

switch (attr->type) {

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