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Message-ID: <20231107083331.901-1-ravi.bangoria@amd.com>
Date: Tue, 7 Nov 2023 14:03:30 +0530
From: Ravi Bangoria <ravi.bangoria@....com>
To: <acme@...nel.org>, <namhyung@...nel.org>
CC: <ravi.bangoria@....com>, <kim.phillips@....com>,
<peterz@...radead.org>, <mingo@...hat.com>, <mark.rutland@....com>,
<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
<irogers@...gle.com>, <adrian.hunter@...el.com>,
<kan.liang@...ux.intel.com>, <changbin.du@...wei.com>,
<yangjihong1@...wei.com>, <zwisler@...omium.org>,
<wangming01@...ngson.cn>, <chenhuacai@...nel.org>,
<kprateek.nayak@....com>, <linux-perf-users@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <sandipan.das@....com>,
<ananth.narayan@....com>, <santosh.shukla@....com>
Subject: [PATCH 1/2] perf tool AMD: Use non-precise cycles as default event on certain Zen2 processors
By default, Perf uses precise cycles event when no explicit event is
specified by user. Precise cycles event is forwarded to ibs_op// pmu
on AMD. However, IBS has hw issue on certain Zen2 processors where
it might raise NMI without sample_valid bit set, which causes Unknown
NMI warnings. (Erratum #1215: IBS (Instruction Based Sampling) Counter
Valid Value May be Incorrect After Exit From Core C6 (CC6) State.) So,
use non-precise cycles as default event on affected processors.
This does not prevent user to use explicit precise cycles event or
ibs_op// pmu directly.
Suggested-by: Arnaldo Carvalho de Melo <acme@...nel.org>
Signed-off-by: Ravi Bangoria <ravi.bangoria@....com>
---
tools/perf/arch/x86/util/evlist.c | 34 +++++++++++++++++++++++++++++++
tools/perf/builtin-record.c | 2 +-
tools/perf/builtin-top.c | 2 +-
tools/perf/util/evlist.c | 12 ++++++++++-
tools/perf/util/evlist.h | 2 ++
5 files changed, 49 insertions(+), 3 deletions(-)
diff --git a/tools/perf/arch/x86/util/evlist.c b/tools/perf/arch/x86/util/evlist.c
index b1ce0c52d88d..f4478179c91b 100644
--- a/tools/perf/arch/x86/util/evlist.c
+++ b/tools/perf/arch/x86/util/evlist.c
@@ -5,6 +5,8 @@
#include "util/evlist.h"
#include "util/parse-events.h"
#include "util/event.h"
+#include "util/env.h"
+#include "linux/string.h"
#include "topdown.h"
#include "evsel.h"
@@ -92,3 +94,35 @@ int arch_evlist__cmp(const struct evsel *lhs, const struct evsel *rhs)
/* Default ordering by insertion index. */
return lhs->core.idx - rhs->core.idx;
}
+
+/*
+ * Precise cycles event is forwarded to ibs_op// pmu on AMD. However, IBS
+ * has hw issue on certain Zen2 processors where it might raise NMI without
+ * sample_valid bit set, which causes Unknown NMI warnings. So default to
+ * non-precise cycles event on affected processors.
+ */
+const char *arch_evlist__default_cycles_event(bool can_profile_kernel)
+{
+ struct perf_env env = { .total_mem = 0, };
+ unsigned int family, model, stepping;
+ bool is_amd;
+ int ret;
+
+ perf_env__cpuid(&env);
+ is_amd = env.cpuid && strstarts(env.cpuid, "AuthenticAMD");
+ if (!is_amd)
+ goto out;
+
+ ret = sscanf(env.cpuid, "%*[^,],%u,%u,%u", &family, &model, &stepping);
+ if (ret == 3 && family == 0x17 && (
+ (model >= 0x30 && model <= 0x3f) ||
+ (model >= 0x60 && model <= 0x7f) ||
+ (model >= 0x90 && model <= 0x9f))) {
+ perf_env__exit(&env);
+ return can_profile_kernel ? "cycles" : "cycles:u";
+ }
+
+out:
+ perf_env__exit(&env);
+ return can_profile_kernel ? "cycles:P" : "cycles:Pu";
+}
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index dcf288a4fb9a..e58d8ac8a77b 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -4150,7 +4150,7 @@ int cmd_record(int argc, const char **argv)
if (rec->evlist->core.nr_entries == 0) {
bool can_profile_kernel = perf_event_paranoid_check(1);
- err = parse_event(rec->evlist, can_profile_kernel ? "cycles:P" : "cycles:Pu");
+ err = parse_event(rec->evlist, evlist__default_cycles_event(can_profile_kernel));
if (err)
goto out;
}
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index ea8c7eca5eee..21368421eddd 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1666,7 +1666,7 @@ int cmd_top(int argc, const char **argv)
if (!top.evlist->core.nr_entries) {
bool can_profile_kernel = perf_event_paranoid_check(1);
- int err = parse_event(top.evlist, can_profile_kernel ? "cycles:P" : "cycles:Pu");
+ int err = parse_event(top.evlist, evlist__default_cycles_event(can_profile_kernel));
if (err)
goto out_delete_evlist;
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index e36da58522ef..406ed851cafc 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -90,6 +90,16 @@ struct evlist *evlist__new(void)
return evlist;
}
+const char * __weak arch_evlist__default_cycles_event(bool can_profile_kernel)
+{
+ return can_profile_kernel ? "cycles:P" : "cycles:Pu";
+}
+
+const char *evlist__default_cycles_event(bool can_profile_kernel)
+{
+ return arch_evlist__default_cycles_event(can_profile_kernel);
+}
+
struct evlist *evlist__new_default(void)
{
struct evlist *evlist = evlist__new();
@@ -100,7 +110,7 @@ struct evlist *evlist__new_default(void)
return NULL;
can_profile_kernel = perf_event_paranoid_check(1);
- err = parse_event(evlist, can_profile_kernel ? "cycles:P" : "cycles:Pu");
+ err = parse_event(evlist, evlist__default_cycles_event(can_profile_kernel));
if (err) {
evlist__delete(evlist);
evlist = NULL;
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 98e7ddb2bd30..7267b4fb1981 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -91,6 +91,8 @@ struct evsel_str_handler {
struct evlist *evlist__new(void);
struct evlist *evlist__new_default(void);
+const char *arch_evlist__default_cycles_event(bool can_profile_kernel);
+const char *evlist__default_cycles_event(bool can_profile_kernel);
struct evlist *evlist__new_dummy(void);
void evlist__init(struct evlist *evlist, struct perf_cpu_map *cpus,
struct perf_thread_map *threads);
--
2.41.0
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