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

[David Ahern]

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>
> > > >
> > > >    #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;?
> > > /* 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.

David
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