On Tue, Apr 07, 2015 at 05:34:58PM -0700, Sukadev Bhattiprolu wrote:
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 1ac99d1..a001582 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -3644,6 +3644,33 @@ static void orphans_remove_work(struct work_struct
> *work)
> put_ctx(ctx);
> }
>
> +/*
> + * Use the transaction interface to read the group of events in @leader.
> + * PMUs like the 24x7 counters in Power, can use this to queue the events
> + * in the ->read() operation and perform the actual read in ->commit_txn.
> + *
> + * Other PMUs can ignore the ->start_txn and ->commit_txn and read each
> + * PMU directly in the ->read() operation.
> + */
> +static int perf_event_read_txn(struct perf_event *leader)
perf_event_read_group() might be a better name. Ah, I see that's already
taken. Bugger.
See the below patch.
> +{
> + int ret;
> + struct perf_event *sub;
> + struct pmu *pmu;
> +
> + pmu = leader->pmu;
> +
> + pmu->start_txn(pmu, PERF_PMU_TXN_READ);
> +
> + perf_event_read(leader);
> + list_for_each_entry(sub, &leader->sibling_list, group_entry)
> + perf_event_read(sub);
> +
> + ret = pmu->commit_txn(pmu, PERF_PMU_TXN_READ);
> +
> + return ret;
> +}
And while were here, should we change the NOP txn implementation to not
call perf_pmu_disable for TXN_READ ?
That seems entirely unneeded in this case.
---
Subject: perf: Rename perf_event_read_{one,group}, perf_read_hw
In order to free up the perf_event_read_group() name:
s/perf_event_read_\(one\|group\)/perf_read_\1/g
s/perf_read_hw/__perf_read/g
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
kernel/events/core.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 06917d537302..869f6accb4f4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3677,7 +3677,7 @@ static void put_event(struct perf_event *event)
* see the comment there.
*
* 2) there is a lock-inversion with mmap_sem through
- * perf_event_read_group(), which takes faults while
+ * perf_read_group(), which takes faults while
* holding ctx->mutex, however this is called after
* the last filedesc died, so there is no possibility
* to trigger the AB-BA case.
@@ -3765,7 +3765,7 @@ u64 perf_event_read_value(struct perf_event *event, u64
*enabled, u64 *running)
}
EXPORT_SYMBOL_GPL(perf_event_read_value);
-static int perf_event_read_group(struct perf_event *event,
+static int perf_read_group(struct perf_event *event,
u64 read_format, char __user *buf)
{
struct perf_event *leader = event->group_leader, *sub;
@@ -3813,7 +3813,7 @@ static int perf_event_read_group(struct perf_event *event,
return ret;
}
-static int perf_event_read_one(struct perf_event *event,
+static int perf_read_one(struct perf_event *event,
u64 read_format, char __user *buf)
{
u64 enabled, running;
@@ -3851,7 +3851,7 @@ static bool is_event_hup(struct perf_event *event)
* Read the performance event - simple non blocking version for now
*/
static ssize_t
-perf_read_hw(struct perf_event *event, char __user *buf, size_t count)
+__perf_read(struct perf_event *event, char __user *buf, size_t count)
{
u64 read_format = event->attr.read_format;
int ret;
@@ -3869,9 +3869,9 @@ perf_read_hw(struct perf_event *event, char __user *buf,
size_t count)
WARN_ON_ONCE(event->ctx->parent_ctx);
if (read_format & PERF_FORMAT_GROUP)
- ret = perf_event_read_group(event, read_format, buf);
+ ret = perf_read_group(event, read_format, buf);
else
- ret = perf_event_read_one(event, read_format, buf);
+ ret = perf_read_one(event, read_format, buf);
return ret;
}
@@ -3884,7 +3884,7 @@ perf_read(struct file *file, char __user *buf, size_t
count, loff_t *ppos)
int ret;
ctx = perf_event_ctx_lock(event);
- ret = perf_read_hw(event, buf, count);
+ ret = __perf_read(event, buf, count);
perf_event_ctx_unlock(event, ctx);
return ret;
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