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

From: David Ahern
Date: Mon Sep 28 2015 - 11:21:20 EST

On 9/28/15 9:16 AM, Scott Wood wrote:
On Mon, 2015-09-28 at 08:31 -0600, David Ahern wrote:
On 9/28/15 7:00 AM, Alexander Yarygin wrote:
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>

-#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
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;?
/* 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,

I agree; don't rely on kvm_events_tp. Define KVM_ENTRY_TRACE and
KVM_EXIT_TRACE like x86.

If you mean defining them in uapi, that doesn't work for arches that have
multiple subarches that may have different trace events. This patchset
doesn't actually implement dynamic support for the subarches, but it avoids
adding constants to uapi headers that only apply to one of the subarches.

I don't agree on relying on kvm_events_tp[0] and [1]. If you need that to be a runtime definition then change KVM_ENTRY_TRACE to const char *kvm_entry_trace and s390 and other arches can have code to set kvm_{entry,exit}_trace at runtime.

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