Re: [PATCH v2 2/9] cxl: add helper to parse through all current events

[Dave Jiang <dave.jiang@intel.com>]

On 9/21/2022 2:09 PM, Alison Schofield wrote:
> On Mon, Sep 19, 2022 at 04:46:46PM -0700, Dave Jiang wrote:
>> Add common function to iterate through and extract the events in the
>> current trace buffer. The function uses tracefs_iterate_raw_events() from
>> libtracefs to go through all the events loaded into a tep_handle. A
>> callback is provided to the API call in order to parse the event. For cxl
>> monitor, an array of interested "systems" is provided in order to filter
>> for the interested events.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>>   cxl/event_trace.c |   33 +++++++++++++++++++++++++++++++++
>>   cxl/event_trace.h |    7 +++++++
>>   cxl/meson.build   |    1 +
>>   meson.build       |    2 ++
>>   4 files changed, 43 insertions(+)
>>
>> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
>> index ffa2a9b9b036..430146ce66f5 100644
>> --- a/cxl/event_trace.c
>> +++ b/cxl/event_trace.c
>> @@ -16,6 +16,7 @@
>>   #include <libcxl.h>
>>   #include <uuid/uuid.h>
>>   #include <traceevent/event-parse.h>
>> +#include <tracefs/tracefs.h>
>>   #include "json.h"
>>   #include "event_trace.h"
>>   
>> @@ -164,3 +165,35 @@ err_jevent:
>>   	free(jnode);
>>   	return rc;
>>   }
>> +
>> +static int cxl_event_parse_cb(struct tep_event *event, struct tep_record *record,
>> +		int cpu, void *ctx)
>> +{
>> +	struct event_ctx *event_ctx = (struct event_ctx *)ctx;
>> +	int rc;
>> +
>> +	/* Filter out all the events that the caller isn't interested in. */
>> +	if (strcmp(event->system, event_ctx->system) != 0)
>> +		return 0;
>> +
> While integrating w poison events, I find I'd like to filter on
> tep_event->name == "cxl_poison" here.
>
> Something like this:
>
> +	if (event_ctx->name) {
> +		if (strcmp(event->name, event_ctx->name) != 0)
> +			return 0;
> +	}
>   
> along w this:
>
> struct event_ctx {
>   	const char *system;
> +	const char *name;
>   	struct list_head jlist_head;
>   };

Ok I can add that.

>
> I guess an all|1 option won't suffice for users wanting a subset.
> See how that fits it w your needs for monitor command. I can always
> filter after the fact if this type of change is not generally useful.
>
> Thanks,
> Alison
>
>
>> +	rc = cxl_event_to_json_callback(event, record, &event_ctx->jlist_head);
>> +	if (rc < 0)
>> +		return rc;
>> +
>> +	return 0;
>> +}
>> +
>> +int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx)
>> +{
>> +	struct tep_handle *tep;
>> +	int rc;
>> +
>> +	tep = tracefs_local_events(NULL);
>> +	if (!tep)
>> +		return -ENOMEM;
>> +
>> +	rc = tracefs_iterate_raw_events(tep, inst, NULL, 0,
>> +			cxl_event_parse_cb, ectx);
>> +	tep_free(tep);
>> +	return rc;
>> +}
>> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
>> index 00975a0b5680..2fbefa1586d9 100644
>> --- a/cxl/event_trace.h
>> +++ b/cxl/event_trace.h
>> @@ -11,4 +11,11 @@ struct jlist_node {
>>   	struct list_node list;
>>   };
>>   
>> +struct event_ctx {
>> +	const char *system;
>> +	struct list_head jlist_head;
>> +};
>> +
>> +int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
>> +
>>   #endif
>> diff --git a/cxl/meson.build b/cxl/meson.build
>> index 8c7733431613..c59876262e76 100644
>> --- a/cxl/meson.build
>> +++ b/cxl/meson.build
>> @@ -21,6 +21,7 @@ cxl_tool = executable('cxl',
>>       json,
>>       versiondep,
>>       traceevent,
>> +    tracefs,
>>     ],
>>     install : true,
>>     install_dir : rootbindir,
>> diff --git a/meson.build b/meson.build
>> index f611e0bdd7f3..c204c8ac52de 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -143,6 +143,8 @@ libudev = dependency('libudev')
>>   uuid = dependency('uuid')
>>   json = dependency('json-c')
>>   traceevent = dependency('libtraceevent')
>> +tracefs = dependency('libtracefs')
>> +
>>   if get_option('docs').enabled()
>>     if get_option('asciidoctor').enabled()
>>       asciidoc = find_program('asciidoctor', required : true)
>>
>>