[PATCH] perf kvm: fix sample_type manipulation

[PATCH] perf kvm: fix sample_type manipulation

[Adrian Hunter]

Manipulating the sample_type of an evsel requires
the use of:
	perf_evsel__set_sample_bit()
and	perf_evsel__reset_sample_bit()

Manipulating the sample type of an evlist requires
the id position to be recalculated.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 tools/perf/builtin-kvm.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 47b3540..0b7c5a9 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1165,16 +1165,16 @@ static int kvm_live_open_events(struct perf_kvm_stat *kvm)
 		struct perf_event_attr *attr = &pos->attr;
 
 		/* make sure these *are* set */
-		attr->sample_type |= PERF_SAMPLE_TID;
-		attr->sample_type |= PERF_SAMPLE_TIME;
-		attr->sample_type |= PERF_SAMPLE_CPU;
-		attr->sample_type |= PERF_SAMPLE_RAW;
+		perf_evsel__set_sample_bit(pos, TID);
+		perf_evsel__set_sample_bit(pos, TIME);
+		perf_evsel__set_sample_bit(pos, CPU);
+		perf_evsel__set_sample_bit(pos, RAW);
 		/* make sure these are *not*; want as small a sample as possible */
-		attr->sample_type &= ~PERF_SAMPLE_PERIOD;
-		attr->sample_type &= ~PERF_SAMPLE_IP;
-		attr->sample_type &= ~PERF_SAMPLE_CALLCHAIN;
-		attr->sample_type &= ~PERF_SAMPLE_ADDR;
-		attr->sample_type &= ~PERF_SAMPLE_READ;
+		perf_evsel__reset_sample_bit(pos, PERIOD);
+		perf_evsel__reset_sample_bit(pos, IP);
+		perf_evsel__reset_sample_bit(pos, CALLCHAIN);
+		perf_evsel__reset_sample_bit(pos, ADDR);
+		perf_evsel__reset_sample_bit(pos, READ);
 		attr->mmap = 0;
 		attr->comm = 0;
 		attr->task = 0;
@@ -1188,6 +1188,8 @@ static int kvm_live_open_events(struct perf_kvm_stat *kvm)
 		attr->disabled = 1;
 	}
 
+	perf_evlist__set_id_pos(evlist);
+
 	err = perf_evlist__open(evlist);
 	if (err < 0) {
 		printf("Couldn't create the events: %s\n", strerror(errno));
-- 
1.7.11.7

Re: [PATCH] perf kvm: fix sample_type manipulation

[Arnaldo Carvalho de Melo]

Em Fri, Sep 06, 2013 at 09:48:54AM +0300, Adrian Hunter escreveu:
> Manipulating the sample_type of an evsel requires
> the use of:
> 	perf_evsel__set_sample_bit()
> and	perf_evsel__reset_sample_bit()

Fine, but...
 
> Manipulating the sample type of an evlist requires
> the id position to be recalculated.

... can't we hide this detail? I.e. we could do it like we do with the
alloc_{mmap,poll}() evlist methods in perf_evlist__mmap(), checking if it was
already done, etc.

This we reduce the contact surface for tools using evlists and evsels.

I.e., this sequence:

 
+	perf_evlist__set_id_pos(evlist);
+
 	err = perf_evlist__open(evlist);

Could remain just:

	err = perf_evlist__open(evlist);

I'm auditing the other calls to evlist now, to check if there are other cases.

Thanks for the patch!

- Arnaldo

 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
>  tools/perf/builtin-kvm.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
> index 47b3540..0b7c5a9 100644
> --- a/tools/perf/builtin-kvm.c
> +++ b/tools/perf/builtin-kvm.c
> @@ -1165,16 +1165,16 @@ static int kvm_live_open_events(struct perf_kvm_stat *kvm)
>  		struct perf_event_attr *attr = &pos->attr;
>  
>  		/* make sure these *are* set */
> -		attr->sample_type |= PERF_SAMPLE_TID;
> -		attr->sample_type |= PERF_SAMPLE_TIME;
> -		attr->sample_type |= PERF_SAMPLE_CPU;
> -		attr->sample_type |= PERF_SAMPLE_RAW;
> +		perf_evsel__set_sample_bit(pos, TID);
> +		perf_evsel__set_sample_bit(pos, TIME);
> +		perf_evsel__set_sample_bit(pos, CPU);
> +		perf_evsel__set_sample_bit(pos, RAW);
>  		/* make sure these are *not*; want as small a sample as possible */
> -		attr->sample_type &= ~PERF_SAMPLE_PERIOD;
> -		attr->sample_type &= ~PERF_SAMPLE_IP;
> -		attr->sample_type &= ~PERF_SAMPLE_CALLCHAIN;
> -		attr->sample_type &= ~PERF_SAMPLE_ADDR;
> -		attr->sample_type &= ~PERF_SAMPLE_READ;
> +		perf_evsel__reset_sample_bit(pos, PERIOD);
> +		perf_evsel__reset_sample_bit(pos, IP);
> +		perf_evsel__reset_sample_bit(pos, CALLCHAIN);
> +		perf_evsel__reset_sample_bit(pos, ADDR);
> +		perf_evsel__reset_sample_bit(pos, READ);
>  		attr->mmap = 0;
>  		attr->comm = 0;
>  		attr->task = 0;
> @@ -1188,6 +1188,8 @@ static int kvm_live_open_events(struct perf_kvm_stat *kvm)
>  		attr->disabled = 1;
>  	}
>  
> +	perf_evlist__set_id_pos(evlist);
> +
>  	err = perf_evlist__open(evlist);
>  	if (err < 0) {
>  		printf("Couldn't create the events: %s\n", strerror(errno));
> -- 
> 1.7.11.7

Re: [PATCH] perf kvm: fix sample_type manipulation

[David Ahern]

On 9/6/13 6:53 AM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Sep 06, 2013 at 09:48:54AM +0300, Adrian Hunter escreveu:
>> Manipulating the sample_type of an evsel requires
>> the use of:
>> 	perf_evsel__set_sample_bit()
>> and	perf_evsel__reset_sample_bit()
>
> Fine, but...

hmmm... this is a relatively new API (7be5ebe8). The kvm-live command 
and my scheduling daemon pre-date its introduction.

>
>> Manipulating the sample type of an evlist requires
>> the id position to be recalculated.

And this is hot of the presses ... 75562573.

>
> ... can't we hide this detail? I.e. we could do it like we do with the
> alloc_{mmap,poll}() evlist methods in perf_evlist__mmap(), checking if it was
> already done, etc.
>
> This we reduce the contact surface for tools using evlists and evsels.
>
> I.e., this sequence:
>
>
> +	perf_evlist__set_id_pos(evlist);
> +
>   	err = perf_evlist__open(evlist);
>
> Could remain just:
>
> 	err = perf_evlist__open(evlist);

perf code has been around a while now and I know there are a number of 
local analysis commands built around it. API changes like this -- 
required ones at that -- need to be simple and some error checking built 
in where possible.

... and documentation for the API on what commands should be doing and 
in what order.

David

Re: [PATCH] perf kvm: fix sample_type manipulation

[David Ahern]

On 9/6/13 12:48 AM, Adrian Hunter wrote:
> Manipulating the sample_type of an evsel requires
> the use of:
> 	perf_evsel__set_sample_bit()
> and	perf_evsel__reset_sample_bit()
>
> Manipulating the sample type of an evlist requires
> the id position to be recalculated.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>


Fixes the regression. Thanks for taking care of it

Tested-by-and-Acked-by: David Ahern <dsahern@gmail.com>