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perf: Reveal PMU type in fdinfo

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It gives useful info on knowing which PMUs are reserved by this process.
Also add config which would be useful.
Testing cycles:

  $ ./perf stat -e cycles &
  $ cat /proc/`pidof perf`/fdinfo/3
  pos:    0
  flags:  02000002
  mnt_id: 16
  ino:    3081
  perf_event_attr.type:   0
  perf_event_attr.config: 0x0
  perf_event_attr.config1:        0x0
  perf_event_attr.config2:        0x0
  perf_event_attr.config3:        0x0
  perf_event_attr.config4:        0x0

Testing L1-dcache-load-misses:

  $ ./perf stat -e L1-dcache-load-misses &
  $ cat /proc/`pidof perf`/fdinfo/3
  pos:    0
  flags:  02000002
  mnt_id: 16
  ino:    1072
  perf_event_attr.type:   3
  perf_event_attr.config: 0x10000
  perf_event_attr.config1:        0x0
  perf_event_attr.config2:        0x0
  perf_event_attr.config3:        0x0
  perf_event_attr.config4:        0x0

Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://patch.msgid.link/20260602181349.3969429-1-ctshao@google.com
This commit is contained in:
Chun-Tse Shao 2026-06-02 11:13:48 -07:00 committed by Peter Zijlstra
parent 1a308a168c
commit 2369ce0f16
1 changed files with 29 additions and 0 deletions
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29
kernel/events/core.c
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@ -58,6 +58,7 @@
#include <linux/percpu-rwsem.h>
#include <linux/unwind_deferred.h>
#include <linux/kvm_types.h>
#include <linux/seq_file.h>
#include "internal.h"
@ -7546,6 +7547,33 @@ static int perf_fasync(int fd, struct file *filp, int on)
return 0;
}
static void perf_show_fdinfo(struct seq_file *m, struct file *f)
{
struct perf_event *event = f->private_data;
struct perf_event_context *ctx;
struct mutex *child_mutex;
ctx = perf_event_ctx_lock(event);
child_mutex = event->parent ? &event->parent->child_mutex : &event->child_mutex;
mutex_lock(child_mutex);
seq_printf(m, "perf_event_attr.type:\t%u\n", event->orig_type);
if (event->pmu)
seq_printf(m, "pmu_type:\t%u\n", event->pmu->type);
seq_printf(m, "perf_event_attr.config:\t0x%llx\n", (unsigned long long)event->attr.config);
seq_printf(m, "perf_event_attr.config1:\t0x%llx\n",
(unsigned long long)event->attr.config1);
seq_printf(m, "perf_event_attr.config2:\t0x%llx\n",
(unsigned long long)event->attr.config2);
seq_printf(m, "perf_event_attr.config3:\t0x%llx\n",
(unsigned long long)event->attr.config3);
seq_printf(m, "perf_event_attr.config4:\t0x%llx\n",
(unsigned long long)event->attr.config4);
mutex_unlock(child_mutex);
perf_event_ctx_unlock(event, ctx);
}
static const struct file_operations perf_fops = {
.release = perf_release,
.read = perf_read,
@ -7554,6 +7582,7 @@ static const struct file_operations perf_fops = {
.compat_ioctl = perf_compat_ioctl,
.mmap = perf_mmap,
.fasync = perf_fasync,
.show_fdinfo = perf_show_fdinfo,
};
/*