On 27 Aug 2025, at 10:58 PM, Adrian Hunter [off-list ref] wrote:

On 15/08/2025 11:34, Athira Rajeev wrote:

quoted

Add vpa dtl pmu auxtrace process function for "perf report -D".
The auxtrace event processing functions are defined in file
"util/powerpc-vpadtl.c". Data structures used includes "struct
powerpc_vpadtl_queue", "struct powerpc_vpadtl" to store the auxtrace
buffers in queue. Different PERF_RECORD_XXX are generated
during recording. PERF_RECORD_AUXTRACE_INFO is processed first
since it is of type perf_user_event_type and perf session event
delivers perf_session__process_user_event() first. Define function
powerpc_vpadtl_process_auxtrace_info() to handle the processing of
PERF_RECORD_AUXTRACE_INFO records. In this function, initialize
the aux buffer queues using auxtrace_queues__init(). Setup the
required infrastructure for aux data processing. The data is collected
per CPU and auxtrace_queue is created for each CPU.

Define powerpc_vpadtl_process_event() function to process
PERF_RECORD_AUXTRACE records. In this, add the event to queue using
auxtrace_queues__add_event() and process the buffer in
powerpc_vpadtl_dump_event(). The first entry in the buffer with
timebase as zero has boot timebase and frequency. Remaining data is of
format for "struct dtl_entry". Define the translation for
dispatch_reasons and preempt_reasons, report this when dump trace is
invoked via powerpc_vpadtl_dump()

Sample output:

  ./perf record -a -e sched:*,vpa_dtl/dtl_all/ -c 1000000000 sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.300 MB perf.data ]

  ./perf report -D

  0 0 0x39b10 [0x30]: PERF_RECORD_AUXTRACE size: 0x690  offset: 0  ref: 0  idx: 0  tid: -1  cpu: 0
  .
  . ... VPA DTL PMU data: size 1680 bytes, entries is 35
  .  00000000: boot_tb: 21349649546353231, tb_freq: 512000000
  .  00000030: dispatch_reason:decrementer interrupt, preempt_reason:H_CEDE, enqueue_to_dispatch_time:7064, ready_to_enqueue_time:187, waiting_to_ready_time:6611773
  .  00000060: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:146, ready_to_enqueue_time:0, waiting_to_ready_time:15359437
  .  00000090: dispatch_reason:decrementer interrupt, preempt_reason:H_CEDE, enqueue_to_dispatch_time:4868, ready_to_enqueue_time:232, waiting_to_ready_time:5100709
  .  000000c0: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:179, ready_to_enqueue_time:0, waiting_to_ready_time:30714243
  .  000000f0: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:197, ready_to_enqueue_time:0, waiting_to_ready_time:15350648
  .  00000120: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:213, ready_to_enqueue_time:0, waiting_to_ready_time:15353446
  .  00000150: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:212, ready_to_enqueue_time:0, waiting_to_ready_time:15355126
  .  00000180: dispatch_reason:decrementer interrupt, preempt_reason:H_CEDE, enqueue_to_dispatch_time:6368, ready_to_enqueue_time:164, waiting_to_ready_time:5104665

Signed-off-by: Athira Rajeev <redacted>
---
tools/perf/util/Build            |   1 +
tools/perf/util/auxtrace.c       |   2 +
tools/perf/util/powerpc-vpadtl.c | 299 +++++++++++++++++++++++++++++++
3 files changed, 302 insertions(+)
create mode 100644 tools/perf/util/powerpc-vpadtl.c

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 4959e7a990e4..5ead46dc98e7 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build

@@ -136,6 +136,7 @@ perf-util-$(CONFIG_AUXTRACE) += arm-spe-decoder/

perf-util-$(CONFIG_AUXTRACE) += hisi-ptt.o
perf-util-$(CONFIG_AUXTRACE) += hisi-ptt-decoder/
perf-util-$(CONFIG_AUXTRACE) += s390-cpumsf.o
+perf-util-$(CONFIG_AUXTRACE) += powerpc-vpadtl.o

ifdef CONFIG_LIBOPENCSD
perf-util-$(CONFIG_AUXTRACE) += cs-etm.o

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index f587d386c5ef..bd1404f26bb7 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c

@@ -1395,6 +1395,8 @@ int perf_event__process_auxtrace_info(struct perf_session *session,

err = hisi_ptt_process_auxtrace_info(event, session);
break;
case PERF_AUXTRACE_VPA_PMU:
+ err = powerpc_vpadtl_process_auxtrace_info(event, session);
+ break;
case PERF_AUXTRACE_UNKNOWN:
default:
return -EINVAL;

diff --git a/tools/perf/util/powerpc-vpadtl.c b/tools/perf/util/powerpc-vpadtl.c
new file mode 100644
index 000000000000..ea7b59c45f4a
--- /dev/null
+++ b/tools/perf/util/powerpc-vpadtl.c

@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * VPA DTL PMU support
+ */
+
+#include <endian.h>
+#include <errno.h>
+#include <byteswap.h>
+#include <inttypes.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/log2.h>
+#include <elf.h>
+#include <limits.h>
+
+#include "cpumap.h"
+#include "color.h"
+#include "evsel.h"
+#include "evlist.h"
+#include "machine.h"
+#include "session.h"
+#include "util.h"
+#include "thread.h"
+#include "debug.h"
+#include "auxtrace.h"
+#include "powerpc-vpadtl.h"
+#include "map.h"
+#include "symbol_conf.h"
+#include "symbol.h"

Are all these #includes really needed

quoted

+
+/*
+ * The DTL entries are of below format
+ */
+struct dtl_entry {
+ u8      dispatch_reason;
+ u8      preempt_reason;
+ u16     processor_id;
+ u32     enqueue_to_dispatch_time;
+ u32     ready_to_enqueue_time;
+ u32     waiting_to_ready_time;
+ u64     timebase;
+ u64     fault_addr;
+ u64     srr0;
+ u64     srr1;
+};

struct dtl_entry is moved in a later patch.
Maybe call it vpadtl_entry or powerpc_vpadtl_entry and
put it in perf/util/event.h since it is eventually needed
in perf/builtin-script.c

Sure

quoted

+
+/*
+ * Structure to save the auxtrace queue
+ */
+struct powerpc_vpadtl {
+ struct auxtrace auxtrace;
+ struct auxtrace_queues queues;
+ struct auxtrace_heap heap;
+ u32 auxtrace_type;
+ struct perf_session *session;
+ struct machine *machine;
+ u32 pmu_type;
+};
+
+struct boottb_freq {
+ u64     boot_tb;
+ u64     tb_freq;
+ u64     timebase;
+ u64     padded[3];
+};
+
+struct powerpc_vpadtl_queue {
+ struct powerpc_vpadtl *vpa;
+ unsigned int queue_nr;
+ struct auxtrace_buffer *buffer;
+ struct thread *thread;
+ bool on_heap;
+ bool done;
+ pid_t pid;
+ pid_t tid;
+ int cpu;
+};
+
+const char *dispatch_reasons[11] = {
+ "external_interrupt",
+ "firmware_internal_event",
+ "H_PROD",
+ "decrementer_interrupt",
+ "system_reset",
+ "firmware_internal_event",
+ "conferred_cycles",
+ "time_slice",
+ "virtual_memory_page_fault",
+ "expropriated_adjunct",
+ "priv_doorbell"};
+
+const char *preempt_reasons[10] = {
+ "unused",
+ "firmware_internal_event",
+ "H_CEDE",
+ "H_CONFER",
+ "time_slice",
+ "migration_hibernation_page_fault",
+ "virtual_memory_page_fault",
+ "H_CONFER_ADJUNCT",
+ "hcall_adjunct",
+ "HDEC_adjunct"};
+
+#define dtl_entry_size 48

sizeof(struct dtl_entry) ?

quoted

+
+/*
+ * Function to dump the dispatch trace data when perf report
+ * is invoked with -D
+ */
+static void powerpc_vpadtl_dump(struct powerpc_vpadtl *vpa __maybe_unused,
+  unsigned char *buf, size_t len)
+{
+ struct dtl_entry *dtl;
+ int pkt_len, pos = 0;
+ const char *color = PERF_COLOR_BLUE;
+
+ color_fprintf(stdout, color,
+ ". ... VPA DTL PMU data: size %zu bytes, entries is %zu\n",
+ len, len/dtl_entry_size);
+
+ if (len % dtl_entry_size)
+ len = len - (len % dtl_entry_size);
+
+ while (len) {
+ pkt_len = 48;

dtl_entry_size ?

Yes, thanks for pointing out. Will change in V2

quoted

+ printf(".");
+ color_fprintf(stdout, color, "  %08x: ", pos);
+ dtl = (struct dtl_entry *)buf;
+ if (dtl->timebase != 0) {
+ printf("dispatch_reason:%s, preempt_reason:%s, enqueue_to_dispatch_time:%d, ready_to_enqueue_time:%d, waiting_to_ready_time:%d\n",
+ dispatch_reasons[dtl->dispatch_reason], preempt_reasons[dtl->preempt_reason], be32_to_cpu(dtl->enqueue_to_dispatch_time),
+ be32_to_cpu(dtl->ready_to_enqueue_time), be32_to_cpu(dtl->waiting_to_ready_time));

Lines are getting a bit long

Will split these.

quoted

+ } else {
+ struct boottb_freq *boot_tb = (struct boottb_freq *)buf;
+
+ printf("boot_tb: %" PRIu64 ", tb_freq: %" PRIu64 "\n", boot_tb->boot_tb, boot_tb->tb_freq);
+ }
+
+ pos += pkt_len;
+ buf += pkt_len;
+ len -= pkt_len;
+ }
+}
+
+static void powerpc_vpadtl_dump_event(struct powerpc_vpadtl *vpa, unsigned char *buf,
+        size_t len)
+{
+ printf(".\n");
+ powerpc_vpadtl_dump(vpa, buf, len);
+}
+
+static int powerpc_vpadtl_process_event(struct perf_session *session __maybe_unused,
+  union perf_event *event __maybe_unused,
+  struct perf_sample *sample __maybe_unused,
+  const struct perf_tool *tool __maybe_unused)
+{
+ return 0;
+}
+
+/*
+ * Process PERF_RECORD_AUXTRACE records
+ */
+static int powerpc_vpadtl_process_auxtrace_event(struct perf_session *session,
+   union perf_event *event,
+   const struct perf_tool *tool __maybe_unused)
+{
+ struct powerpc_vpadtl *vpa = container_of(session->auxtrace, struct powerpc_vpadtl,
+      auxtrace);

Might be worth adding a helper like

static struct powerpc_vpadtl *session_to_vpa(struct perf_session *session)
{
return container_of(session->auxtrace, struct powerpc_vpadtl, auxtrace);
}

Ok Adrian

quoted

+ struct auxtrace_buffer *buffer;
+ off_t data_offset;
+ int fd = perf_data__fd(session->data);
+ int err;
+
+ if (perf_data__is_pipe(session->data)) {
+ data_offset = 0;
+ } else {
+ data_offset = lseek(fd, 0, SEEK_CUR);
+ if (data_offset == -1)
+ return -errno;
+ }
+
+ err = auxtrace_queues__add_event(&vpa->queues, session, event,
+  data_offset, &buffer);

auxtrace_queues__add_event() is only needed here if there is no
auxtrace index, however an auxtrace index is always written for
new perf.data files.  The index gets processed and data queued
by auxtrace_queues__process_index() which is added in patch 11.

Piped data, on the other hand, has no index and needs to be
handled here.

So:

if (perf_data__is_pipe(session->data)) {
err = auxtrace_queues__add_event(&vpa->queues, session, event, 0, &buffer);
if (err)
return err;
}

Ok, will handle this change

quoted

+ if (err)
+ return err;
+
+ /* Dump here now we have copied a piped trace out of the pipe */
+ if (dump_trace) {
+ if (auxtrace_buffer__get_data(buffer, fd)) {
+ powerpc_vpadtl_dump_event(vpa, buffer->data,
+      buffer->size);

Unnecessary line wrap

quoted

+ auxtrace_buffer__put_data(buffer);
+ }
+ }
+
+ return 0;
+}
+
+static int powerpc_vpadtl_flush(struct perf_session *session __maybe_unused,
+  const struct perf_tool *tool __maybe_unused)
+{
+ return 0;
+}
+
+static void powerpc_vpadtl_free_queue(void *priv)
+{
+ struct powerpc_vpadtl_queue *vpaq = priv;
+
+ if (!vpaq)
+ return;
+
+ free(vpaq);
+}
+
+static void powerpc_vpadtl_free_events(struct perf_session *session)
+{
+ struct powerpc_vpadtl *vpa = container_of(session->auxtrace, struct powerpc_vpadtl,
+      auxtrace);
+ struct auxtrace_queues *queues = &vpa->queues;
+ unsigned int i;
+
+ for (i = 0; i < queues->nr_queues; i++) {
+ powerpc_vpadtl_free_queue(queues->queue_array[i].priv);

This is the same as free(queues->queue_array[i].priv)

quoted

+ queues->queue_array[i].priv = NULL;

Could all be reduced to zfree(queues->queue_array[i].priv)

Sure

quoted

+ }
+ auxtrace_queues__free(queues);
+}
+
+static void powerpc_vpadtl_free(struct perf_session *session)
+{
+ struct powerpc_vpadtl *vpa = container_of(session->auxtrace, struct powerpc_vpadtl,
+      auxtrace);
+
+ auxtrace_heap__free(&vpa->heap);
+ powerpc_vpadtl_free_events(session);
+ session->auxtrace = NULL;
+ free(vpa);
+}
+
+static const char * const powerpc_vpadtl_info_fmts[] = {
+ [POWERPC_VPADTL_TYPE] = "  PMU Type           %"PRId64"\n",
+};
+
+static void powerpc_vpadtl_print_info(__u64 *arr)
+{
+ if (!dump_trace)
+ return;
+
+ fprintf(stdout, powerpc_vpadtl_info_fmts[POWERPC_VPADTL_TYPE], arr[POWERPC_VPADTL_TYPE]);
+}
+
+/*
+ * Process the PERF_RECORD_AUXTRACE_INFO records and setup
+ * the infrastructure to process auxtrace events. PERF_RECORD_AUXTRACE_INFO
+ * is processed first since it is of type perf_user_event_type.
+ * Initialise the aux buffer queues using auxtrace_queues__init().
+ * auxtrace_queue is created for each CPU.
+ */
+int powerpc_vpadtl_process_auxtrace_info(union perf_event *event,
+   struct perf_session *session)
+{
+ struct perf_record_auxtrace_info *auxtrace_info = &event->auxtrace_info;
+ size_t min_sz = sizeof(u64) * POWERPC_VPADTL_TYPE;
+ struct powerpc_vpadtl *vpa;
+ int err;
+
+ if (auxtrace_info->header.size < sizeof(struct perf_record_auxtrace_info) +
+ min_sz)
+ return -EINVAL;
+
+ vpa = zalloc(sizeof(struct powerpc_vpadtl));
+ if (!vpa)
+ return -ENOMEM;
+
+ err = auxtrace_queues__init(&vpa->queues);
+ if (err)
+ goto err_free;
+
+ vpa->session = session;
+ vpa->machine = &session->machines.host; /* No kvm support */
+ vpa->auxtrace_type = auxtrace_info->type;
+ vpa->pmu_type = auxtrace_info->priv[POWERPC_VPADTL_TYPE];
+
+ vpa->auxtrace.process_event = powerpc_vpadtl_process_event;
+ vpa->auxtrace.process_auxtrace_event = powerpc_vpadtl_process_auxtrace_event;
+ vpa->auxtrace.flush_events = powerpc_vpadtl_flush;
+ vpa->auxtrace.free_events = powerpc_vpadtl_free_events;
+ vpa->auxtrace.free = powerpc_vpadtl_free;
+ session->auxtrace = &vpa->auxtrace;
+
+ powerpc_vpadtl_print_info(&auxtrace_info->priv[0]);
+
+ return 0;
+
+err_free:
+ free(vpa);
+ return err;
+}