Re: [PATCH v8 1/4] perf,kvm/{x86,s390}: Remove dependency on uapi/kvm_perf.h

From: Hemant Kumar
Date: Wed Sep 30 2015 - 14:12:26 EST

Hi,

Thanks for the review.

On 09/28/2015 06:30 PM, Alexander Yarygin wrote:
Hemant Kumar <hemant@xxxxxxxxxxxxxxxxxx> writes:

Its better to remove the dependency on uapi/kvm_perf.h to allow dynamic
discovery of kvm events (if its needed). To do this, some extern
variables have been introduced with which we can keep the generic
functions generic.

Signed-off-by: Hemant Kumar <hemant@xxxxxxxxxxxxxxxxxx>
---
Changes since v7:
- Removed __maybe_unused for some parameters which weren't needed.

tools/perf/arch/s390/util/kvm-stat.c | 10 ++++++++-
tools/perf/arch/x86/util/kvm-stat.c | 12 ++++++++++-
tools/perf/builtin-kvm.c | 39 +++++++++++++++++++++++-------------
tools/perf/util/kvm-stat.h | 3 +++
4 files changed, 48 insertions(+), 16 deletions(-)
Hello,


The patchset doesn't break s390 code (and at least build on x86), but I

Thanks for testing it on s390.

don't really like some things here (e.g. direct access to
kvm_events_tp), see below.

Thanks.

CC: David Ahern

diff --git a/tools/perf/arch/s390/util/kvm-stat.c b/tools/perf/arch/s390/util/kvm-stat.c
index a5dbc07..c2acb3e 100644
--- a/tools/perf/arch/s390/util/kvm-stat.c
+++ b/tools/perf/arch/s390/util/kvm-stat.c
@@ -10,7 +10,11 @@
*/

#include "../../util/kvm-stat.h"
-#include <asm/kvm_perf.h>
+#include <asm/sie.h>
+
+#define DECODE_STR_LEN 40
+#define VCPU_ID "id"
+#define KVM_EXIT_REASON "icptcode"

I would probably drop them. There are no users besides newly
introduced const char *vcpu_id_str and decore_str_len etc anyway.

Right, will drop them.

define_exit_reasons_table(sie_exit_reasons, sie_intercept_code);
define_exit_reasons_table(sie_icpt_insn_codes, icpt_insn_codes);
@@ -83,6 +87,10 @@ const char * const kvm_events_tp[] = {
NULL,
};

+const char *vcpu_id_str = VCPU_ID;
+const int decode_str_len = DECODE_STR_LEN;
+const char *exit_reason_code = KVM_EXIT_REASON;
+
struct kvm_reg_events_ops kvm_reg_events_ops[] = {
{ .name = "vmexit", .ops = &exit_events },
{ NULL, NULL },
diff --git a/tools/perf/arch/x86/util/kvm-stat.c b/tools/perf/arch/x86/util/kvm-stat.c
index 14e4e66..2d0d43b5 100644
--- a/tools/perf/arch/x86/util/kvm-stat.c
+++ b/tools/perf/arch/x86/util/kvm-stat.c
@@ -1,5 +1,11 @@
#include "../../util/kvm-stat.h"
-#include <asm/kvm_perf.h>
+#include <asm/svm.h>
+#include <asm/vmx.h>
+#include <asm/kvm.h>
+
+#define DECODE_STR_LEN 20
+#define VCPU_ID "vcpu_id"
+#define KVM_EXIT_REASON "exit_reason"

define_exit_reasons_table(vmx_exit_reasons, VMX_EXIT_REASONS);
define_exit_reasons_table(svm_exit_reasons, SVM_EXIT_REASONS);
@@ -129,6 +135,10 @@ const char * const kvm_events_tp[] = {
NULL,
};

+const char *vcpu_id_str = VCPU_ID;
+const int decode_str_len = DECODE_STR_LEN;
+const char *exit_reason_code = KVM_EXIT_REASON;
+
struct kvm_reg_events_ops kvm_reg_events_ops[] = {
{ .name = "vmexit", .ops = &exit_events },
{ .name = "mmio", .ops = &mmio_events },
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index fc1cffb..ef25fcf 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -31,20 +31,18 @@
#include <math.h>

#ifdef HAVE_KVM_STAT_SUPPORT
-#include <asm/kvm_perf.h>
#include "util/kvm-stat.h"

-void exit_event_get_key(struct perf_evsel *evsel,
- struct perf_sample *sample,
+void exit_event_get_key(struct perf_evsel *evsel, struct perf_sample *sample,
struct event_key *key)
{
key->info = 0;
- key->key = perf_evsel__intval(evsel, sample, KVM_EXIT_REASON);
+ key->key = perf_evsel__intval(evsel, sample, exit_reason_code);
}

bool kvm_exit_event(struct perf_evsel *evsel)
{
- return !strcmp(evsel->name, KVM_EXIT_TRACE);
+ return !strncmp(evsel->name, kvm_events_tp[1], strlen(evsel->name));
}
Hmm, direct access to kvm_events_tp? Maybe add a getter for this or
something like extern char *kvm_exit_trace;?

Makes sense, will make them extern const kvm_{exit,entry}_trace and
assign them in their respective archs.

/* why strncmp? */

bool exit_event_begin(struct perf_evsel *evsel,
@@ -60,7 +58,7 @@ bool exit_event_begin(struct perf_evsel *evsel,

bool kvm_entry_event(struct perf_evsel *evsel)
{
- return !strcmp(evsel->name, KVM_ENTRY_TRACE);
+ return !strncmp(evsel->name, kvm_events_tp[0], strlen(evsel->name));
}

bool exit_event_end(struct perf_evsel *evsel,
@@ -71,8 +69,8 @@ bool exit_event_end(struct perf_evsel *evsel,
}

static const char *get_exit_reason(struct perf_kvm_stat *kvm,
- struct exit_reasons_table *tbl,
- u64 exit_code)
+ struct exit_reasons_table *tbl,
+ u64 exit_code)
{
while (tbl->reason != NULL) {
if (tbl->exit_code == exit_code)
@@ -92,7 +90,7 @@ void exit_event_decode_key(struct perf_kvm_stat *kvm,
const char *exit_reason = get_exit_reason(kvm, key->exit_reasons,
key->key);

- scnprintf(decode, DECODE_STR_LEN, "%s", exit_reason);
+ scnprintf(decode, decode_str_len, "%s", exit_reason);
}

static bool register_kvm_events_ops(struct perf_kvm_stat *kvm)
@@ -358,7 +356,12 @@ static bool handle_end_event(struct perf_kvm_stat *kvm,
time_diff = sample->time - time_begin;

if (kvm->duration && time_diff > kvm->duration) {
- char decode[DECODE_STR_LEN];
+ char *decode = zalloc(decode_str_len);
+
+ if (!decode) {
+ pr_err("Not enough memory\n");
+ return false;
+ }
I think char decode[decode_str_len]; should work or we can allocate this
once globally (e.g. put it into struct perf_kvm_stat)? Not sure.

kvm->events_ops->decode_key(kvm, &event->key, decode);
if (!skip_event(decode)) {
@@ -366,6 +369,7 @@ static bool handle_end_event(struct perf_kvm_stat *kvm,
sample->time, sample->pid, vcpu_record->vcpu_id,
decode, time_diff/1000);
}
+ free(decode);
}

return update_kvm_event(event, vcpu, time_diff);
@@ -386,7 +390,8 @@ struct vcpu_event_record *per_vcpu_record(struct thread *thread,
return NULL;
}

- vcpu_record->vcpu_id = perf_evsel__intval(evsel, sample, VCPU_ID);
+ vcpu_record->vcpu_id = perf_evsel__intval(evsel, sample,
+ vcpu_id_str);
thread__set_priv(thread, vcpu_record);
}

@@ -575,7 +580,7 @@ static void show_timeofday(void)

static void print_result(struct perf_kvm_stat *kvm)
{
- char decode[DECODE_STR_LEN];
+ char *decode;
struct kvm_event *event;
int vcpu = kvm->trace_vcpu;

@@ -584,9 +589,14 @@ static void print_result(struct perf_kvm_stat *kvm)
show_timeofday();
}

+ decode = zalloc(decode_str_len);
+ if (!decode) {
+ pr_err("Not enough memory\n");
+ return;
+ }
pr_info("\n\n");
print_vcpu_info(kvm);
- pr_info("%*s ", DECODE_STR_LEN, kvm->events_ops->name);
+ pr_info("%*s ", decode_str_len, kvm->events_ops->name);
pr_info("%10s ", "Samples");
pr_info("%9s ", "Samples%");

@@ -605,7 +615,7 @@ static void print_result(struct perf_kvm_stat *kvm)
min = get_event_min(event, vcpu);

kvm->events_ops->decode_key(kvm, &event->key, decode);
- pr_info("%*s ", DECODE_STR_LEN, decode);
+ pr_info("%*s ", decode_str_len, decode);
pr_info("%10llu ", (unsigned long long)ecount);
pr_info("%8.2f%% ", (double)ecount / kvm->total_count * 100);
pr_info("%8.2f%% ", (double)etime / kvm->total_time * 100);
@@ -615,6 +625,7 @@ static void print_result(struct perf_kvm_stat *kvm)
kvm_event_rel_stddev(vcpu, event));
pr_info("\n");
}
+ free(decode);

pr_info("\nTotal Samples:%" PRIu64 ", Total events handled time:%.2fus.\n\n",
kvm->total_count, kvm->total_time / 1e3);
diff --git a/tools/perf/util/kvm-stat.h b/tools/perf/util/kvm-stat.h
index ae825d4..59ed51c 100644
--- a/tools/perf/util/kvm-stat.h
+++ b/tools/perf/util/kvm-stat.h
@@ -136,5 +136,8 @@ int cpu_isa_init(struct perf_kvm_stat *kvm, const char *cpuid);
extern const char * const kvm_events_tp[];
extern struct kvm_reg_events_ops kvm_reg_events_ops[];
extern const char * const kvm_skip_events[];
+extern const char *vcpu_id_str;
+extern const int decode_str_len;
+extern const char *exit_reason_code;

#endif /* __PERF_KVM_STAT_H */

--
Thanks,
Hemant Kumar

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