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From: Tomasz Duszynski <tduszynski@marvell.com>
To: <dev@dpdk.org>, Jerin Jacob <jerinj@marvell.com>, Sunil Kumar Kori
<skori@marvell.com>
CC: <thomas@monjalon.net>, Tomasz Duszynski <tduszynski@marvell.com>
Subject: [PATCH v2 4/4] eal: add PMU support to tracing library
Date: Mon, 21 Nov 2022 13:11:21 +0100
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In order to profile app one needs to store significant amount of samples
somewhere for an analysis latern on. Since trace library supports
storing data in a CTF format lets take adventage of that and add a
dedicated PMU tracepoint.
Signed-off-by: Tomasz Duszynski <tduszynski@marvell.com>
---
app/test/test_trace_perf.c | 4 ++
doc/guides/prog_guide/profile_app.rst | 5 ++
doc/guides/prog_guide/trace_lib.rst | 32 ++++++++++++
lib/eal/common/eal_common_trace_points.c | 3 ++
lib/eal/common/rte_pmu.c | 63 ++++++++++++++++++++++++
lib/eal/include/rte_eal_trace.h | 11 +++++
lib/eal/version.map | 1 +
7 files changed, 119 insertions(+)
diff --git a/app/test/test_trace_perf.c b/app/test/test_trace_perf.c
index 46ae7d8074..4851b6852f 100644
--- a/app/test/test_trace_perf.c
+++ b/app/test/test_trace_perf.c
@@ -114,6 +114,8 @@ worker_fn_##func(void *arg) \
#define GENERIC_DOUBLE rte_eal_trace_generic_double(3.66666)
#define GENERIC_STR rte_eal_trace_generic_str("hello world")
#define VOID_FP app_dpdk_test_fp()
+/* 0 corresponds first event passed via --trace= */
+#define READ_PMU rte_eal_trace_pmu_read(0)
WORKER_DEFINE(GENERIC_VOID)
WORKER_DEFINE(GENERIC_U64)
@@ -122,6 +124,7 @@ WORKER_DEFINE(GENERIC_FLOAT)
WORKER_DEFINE(GENERIC_DOUBLE)
WORKER_DEFINE(GENERIC_STR)
WORKER_DEFINE(VOID_FP)
+WORKER_DEFINE(READ_PMU)
static void
run_test(const char *str, lcore_function_t f, struct test_data *data, size_t sz)
@@ -174,6 +177,7 @@ test_trace_perf(void)
run_test("double", worker_fn_GENERIC_DOUBLE, data, sz);
run_test("string", worker_fn_GENERIC_STR, data, sz);
run_test("void_fp", worker_fn_VOID_FP, data, sz);
+ run_test("read_pmu", worker_fn_READ_PMU, data, sz);
rte_free(data);
return TEST_SUCCESS;
diff --git a/doc/guides/prog_guide/profile_app.rst b/doc/guides/prog_guide/profile_app.rst
index 8fc1b20cab..977800ea01 100644
--- a/doc/guides/prog_guide/profile_app.rst
+++ b/doc/guides/prog_guide/profile_app.rst
@@ -16,6 +16,11 @@ that information, perf being an example here. Though in some scenarios, eg. when
isolated (nohz_full) and run dedicated tasks, using perf is less than ideal. In such cases one can
read specific events directly from application via ``rte_pmu_read()``.
+Alternatively tracing library can be used which offers dedicated tracepoint
+``rte_eal_trace_pmu_event()``.
+
+Refer to :doc:`../prog_guide/trace_lib` for more details.
+
Profiling on x86
----------------
diff --git a/doc/guides/prog_guide/trace_lib.rst b/doc/guides/prog_guide/trace_lib.rst
index 9a8f38073d..9a845fd86f 100644
--- a/doc/guides/prog_guide/trace_lib.rst
+++ b/doc/guides/prog_guide/trace_lib.rst
@@ -46,6 +46,7 @@ DPDK tracing library features
trace format and is compatible with ``LTTng``.
For detailed information, refer to
`Common Trace Format <https://diamon.org/ctf/>`_.
+- Support reading PMU events on ARM64 and x86 (Intel)
How to add a tracepoint?
------------------------
@@ -137,6 +138,37 @@ the user must use ``RTE_TRACE_POINT_FP`` instead of ``RTE_TRACE_POINT``.
``RTE_TRACE_POINT_FP`` is compiled out by default and it can be enabled using
the ``enable_trace_fp`` option for meson build.
+PMU tracepoint
+--------------
+
+Performance measurement unit (PMU) event values can be read from hardware
+registers using predefined ``rte_pmu_read`` tracepoint.
+
+Tracing is enabled via ``--trace`` EAL option by passing both expression
+matching PMU tracepoint name i.e ``lib.eal.pmu.read`` and expression
+``e=ev1[,ev2,...]`` matching particular events::
+
+ --trace='*pmu.read\|e=cpu_cycles,l1d_cache'
+
+Event names are available under ``/sys/bus/event_source/devices/PMU/events``
+directory, where ``PMU`` is a placeholder for either a ``cpu`` or a directory
+containing ``cpus``.
+
+In contrary to other tracepoints this does not need any extra variables
+added to source files. Instead, caller passes index which follows the order of
+events specified via ``--trace`` parameter. In the following example index ``0``
+corresponds to ``cpu_cyclces`` while index ``1`` corresponds to ``l1d_cache``.
+
+.. code-block:: c
+
+ ...
+ rte_eal_trace_pmu_read(0);
+ rte_eal_trace_pmu_read(1);
+ ...
+
+PMU tracing support must be explicitly enabled using the ``enable_trace_fp``
+option for meson build.
+
Event record mode
-----------------
diff --git a/lib/eal/common/eal_common_trace_points.c b/lib/eal/common/eal_common_trace_points.c
index 0b0b254615..de918ca618 100644
--- a/lib/eal/common/eal_common_trace_points.c
+++ b/lib/eal/common/eal_common_trace_points.c
@@ -75,3 +75,6 @@ RTE_TRACE_POINT_REGISTER(rte_eal_trace_intr_enable,
lib.eal.intr.enable)
RTE_TRACE_POINT_REGISTER(rte_eal_trace_intr_disable,
lib.eal.intr.disable)
+
+RTE_TRACE_POINT_REGISTER(rte_eal_trace_pmu_read,
+ lib.eal.pmu.read)
diff --git a/lib/eal/common/rte_pmu.c b/lib/eal/common/rte_pmu.c
index dc169fb2cf..6a417f74a9 100644
--- a/lib/eal/common/rte_pmu.c
+++ b/lib/eal/common/rte_pmu.c
@@ -19,6 +19,7 @@
#include <rte_tailq.h>
#include "pmu_private.h"
+#include "eal_trace.h"
#define EVENT_SOURCE_DEVICES_PATH "/sys/bus/event_source/devices"
@@ -403,11 +404,70 @@ rte_pmu_add_event(const char *name)
return event->index;
}
+static void
+add_events(const char *pattern)
+{
+ char *token, *copy;
+ int ret;
+
+ copy = strdup(pattern);
+ if (!copy)
+ return;
+
+ token = strtok(copy, ",");
+ while (token) {
+ ret = rte_pmu_add_event(token);
+ if (ret < 0)
+ RTE_LOG(ERR, EAL, "failed to add %s event\n", token);
+
+ token = strtok(NULL, ",");
+ }
+
+ free(copy);
+}
+
+static void
+add_events_by_pattern(const char *pattern)
+{
+ regmatch_t rmatch;
+ char buf[BUFSIZ];
+ unsigned int num;
+ regex_t reg;
+
+ /* events are matched against occurrences of e=ev1[,ev2,..] pattern */
+ if (regcomp(®, "e=([_[:alnum:]-],?)+", REG_EXTENDED))
+ return;
+
+ for (;;) {
+ if (regexec(®, pattern, 1, &rmatch, 0))
+ break;
+
+ num = rmatch.rm_eo - rmatch.rm_so;
+ if (num > sizeof(buf))
+ num = sizeof(buf);
+
+ /* skip e= pattern prefix */
+ memcpy(buf, pattern + rmatch.rm_so + 2, num - 2);
+ buf[num] = '\0';
+ add_events(buf);
+
+ pattern += rmatch.rm_eo;
+ }
+
+ regfree(®);
+}
+
void
eal_pmu_init(void)
{
+ struct trace_arg *arg;
+ struct trace *trace;
int ret;
+ trace = trace_obj_get();
+ if (!trace)
+ RTE_LOG(WARNING, EAL, "tracing not initialized\n");
+
pmu = rte_calloc(NULL, 1, sizeof(*pmu), RTE_CACHE_LINE_SIZE);
if (!pmu) {
RTE_LOG(ERR, EAL, "failed to alloc PMU\n");
@@ -429,6 +489,9 @@ eal_pmu_init(void)
goto out;
}
+ STAILQ_FOREACH(arg, &trace->args, next)
+ add_events_by_pattern(arg->val);
+
return;
out:
free(pmu->name);
diff --git a/lib/eal/include/rte_eal_trace.h b/lib/eal/include/rte_eal_trace.h
index 5ef4398230..2a10f63e97 100644
--- a/lib/eal/include/rte_eal_trace.h
+++ b/lib/eal/include/rte_eal_trace.h
@@ -17,6 +17,7 @@ extern "C" {
#include <rte_alarm.h>
#include <rte_interrupts.h>
+#include <rte_pmu.h>
#include <rte_trace_point.h>
#include "eal_interrupts.h"
@@ -279,6 +280,16 @@ RTE_TRACE_POINT(
rte_trace_point_emit_string(cpuset);
)
+/* PMU */
+RTE_TRACE_POINT_FP(
+ rte_eal_trace_pmu_read,
+ RTE_TRACE_POINT_ARGS(int index),
+ uint64_t val;
+ rte_trace_point_emit_int(index);
+ val = rte_pmu_read(index);
+ rte_trace_point_emit_u64(val);
+)
+
#ifdef __cplusplus
}
#endif
diff --git a/lib/eal/version.map b/lib/eal/version.map
index 1ebd842f34..b49a430c84 100644
--- a/lib/eal/version.map
+++ b/lib/eal/version.map
@@ -442,6 +442,7 @@ EXPERIMENTAL {
rte_thread_join;
# added in 23.03
+ __rte_eal_trace_pmu_read; # WINDOWS_NO_EXPORT
rte_pmu_add_event; # WINDOWS_NO_EXPORT
rte_pmu_read; # WINDOWS_NO_EXPORT
};
--
2.25.1