Hi Jérémie, Sorry for being a little impatient. Please do let me know if you can provide some information regarding my previous email.
Thanks! Salman -- Salman Rafiq Geschäftsfeld Industrial Communication Fraunhofer-Institut für Eingebettete Systeme und Kommunikationstechnik ESK Hansastraße 32 | 80686 München Telefon, Fax: +49 89 547088-356 | +49 89 547088-221 E-Mail: [email protected] Internet: http://www.esk.fraunhofer.de http://www.twitter.com/FraunhoferESK ________________________________________ From: Salman Rafiq [[email protected]] Sent: Wednesday, October 23, 2013 4:50 PM To: Jérémie Galarneau; Mathieu Desnoyers Cc: [email protected]; Julien Desfossez Subject: Re: [lttng-dev] Reading CTF trace using Babeltrace API Hello again :) While reading Kernel trace events (system calls), I came across an issue related to reading the field 'args' inside 'sys_unknown' system call event. Below is the information I get using public babeltrace API's for the event field type. Ctf_type_id = 8 (CTF_TYPE_ARRAY) But when I try to read the value for the field using the following API char * bt_ctf_get_char_array(const struct bt_definition *field); I receive null value. Also it gives me warning that I am instead extracting a String. [warning] Extracting String Also, I am unable to read the value using the following API. char *bt_ctf_get_string(const struct bt_definition *field); below is the sample event recorded: [00002934900435406801] (+0.000009630) sys_unknown: { cpu_id = 3 }, { id = 277, args = [ [0] = 22, [1] = 0, [2] = 4096, [3] = 2, [4] = 4096, [5] = 5 ] } AND the event definition: event { name = sys_unknown; id = 2; stream_id = 0; fields := struct { integer { size = 32; align = 8; signed = 0; encoding = none; base = 10; } _id integer { size = 64; align = 8; signed = 0; encoding = none; base = 10; } _args[6]; }; }; Any suggestion related to that will be very helpful. Thanks! Best Regards, Salman -- Salman Rafiq Geschäftsfeld Industrial Communication Fraunhofer-Institut für Eingebettete Systeme und Kommunikationstechnik ESK Hansastraße 32 | 80686 München Telefon, Fax: +49 89 547088-356 | +49 89 547088-221 E-Mail: [email protected] Internet: http://www.esk.fraunhofer.de http://www.twitter.com/FraunhoferESK -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jérémie Galarneau Sent: Mittwoch, 9. Oktober 2013 01:50 To: Mathieu Desnoyers Cc: Salman Rafiq; Julien Desfossez; [email protected] Subject: Re: Reading CTF trace using Babeltrace API On Tue, Oct 8, 2013 at 7:14 PM, Mathieu Desnoyers <[email protected]> wrote: > ----- Original Message ----- >> From: "Jérémie Galarneau" <[email protected]> >> To: "Salman Rafiq" <[email protected]> >> Cc: [email protected], [email protected], "Mathieu >> Desnoyers" <[email protected]> >> Sent: Tuesday, October 8, 2013 2:52:38 PM >> Subject: Re: Reading CTF trace using Babeltrace API > [...] >> >> The problem is that the "id" fields in both struct >> event_header_compact and event_header_large acts as a variant's tag >> enumeration. >> >> For instance, if we take a look at the event_header_compact >> structure, >> >> struct event_header_compact { >> enum : uint5_t { compact = 0 ... 30, extended = 31 } id; >> variant <id> { >> struct { >> uint27_clock_monotonic_t timestamp; >> } compact; >> struct { >> uint32_t id; >> uint64_clock_monotonic_t timestamp; >> } extended; >> } v; >> } align(8); >> >> The "enum id" field will indicate the event's id if it has a value of >> [0, 30]. It also indicates that the "compact" structure is selected >> in the variant that follows. If id == 31, the "extended" structure is >> selected, which means that you should retrieve the "id" field's value >> from that structure. >> >> Since code is worth a thousand words, here's a more complete code >> sample to read the id fields. >> >> while ((ctf_event = bt_ctf_iter_read_event(iter))) { >> uint64_t event_id = 0; >> const struct bt_definition *stream_event_header_scope = >> bt_ctf_get_top_level_scope( >> ctf_event, BT_STREAM_EVENT_HEADER); >> const struct bt_definition *id_definition = >> bt_ctf_get_field(ctf_event, stream_event_header_scope, >> "id"); >> const struct bt_definition *v_definition = >> bt_ctf_get_field(ctf_event, stream_event_header_scope, >> "v"); >> >> /* "id may be an enum, get the underlying integer if it's the case */ >> if (id_definition && >> bt_ctf_field_type(bt_ctf_get_decl_from_def(id_definition)) == >> CTF_TYPE_ENUM) { >> id_definition = bt_ctf_get_enum_int(id_definition); >> } >> >> /* Check if there is a "v" field and if it contains an "id" field */ >> if (v_definition && >> bt_ctf_field_type(bt_ctf_get_decl_from_def(v_definition)) == >> CTF_TYPE_STRUCT) { >> struct bt_definition const * const *list = NULL; >> unsigned int count = 0; >> unsigned int i; >> >> ret = bt_ctf_get_field_list(ctf_event, v_definition, >> &list, &count); >> if (ret) { >> goto end; >> } >> >> for (i = 0; i < count; i++) { >> const char *name = >> bt_ctf_field_name(list[i]); >> >> if (strcmp("id", name) == 0) { >> id_definition = list[i]; >> break; >> } >> } > > Instead of doing this bt_ctf_get_field_list() and iteration, can't we simply > use bt_ctf_get_field() to try getting the struct bt_definition ? Right. I was under the impression the bt_ctf_get_field() would only work on scopes, but it's not the case. Thanks! Jérémie > > Thanks, > > Mathieu > >> } >> >> if (id_definition && >> bt_ctf_field_type(bt_ctf_get_decl_from_def(id_definition)) == >> CTF_TYPE_INTEGER) { >> event_id = bt_ctf_get_uint64(id_definition); >> } >> >> printf("id = %" PRIu64 "\n", event_id); } >> >> Regards, >> Jérémie >> >> > Thanks a lot! >> > >> > Regards, >> > Salman >> > >> > -- >> > Salman Rafiq >> > Geschäftsfeld Industrial Communication Fraunhofer-Institut für >> > Eingebettete Systeme und Kommunikationstechnik ESK >> > >> > Hansastraße 32 | 80686 München >> > Telefon, Fax: +49 89 547088-356 | +49 89 547088-221 >> > E-Mail: [email protected] >> > >> > Internet: >> > http://www.esk.fraunhofer.de >> > http://www.twitter.com/FraunhoferESK >> > >> > >> > -----Original Message----- >> > From: [email protected] >> > [mailto:[email protected]] On Behalf Of Jérémie Galarneau >> > Sent: Mittwoch, 2. Oktober 2013 20:25 >> > To: Salman Rafiq >> > Cc: [email protected]; [email protected]; Mathieu >> > Desnoyers >> > Subject: Re: Reading CTF trace using Babeltrace API >> > >> > On Wed, Oct 2, 2013 at 12:55 PM, Salman Rafiq >> > <[email protected]> wrote: >> >> Dear LTTngers, >> >> >> >> I would like to ask few questions related to the API's for reading >> >> CTF traces. >> >> >> >> 1. Is there any way to read CTF metadata independently, like we >> >> have certain API's to read the events. >> >> >> > >> > Not from the public API, unfortunately. >> > >> >> 2. There are certain scopes defined in ctf/events.h like: >> >> BT_TRACE_PACKET_HEADER = 0, >> >> BT_STREAM_PACKET_CONTEXT = 1, >> >> BT_STREAM_EVENT_HEADER = 2, >> >> BT_STREAM_EVENT_CONTEXT = 3, >> >> BT_EVENT_CONTEXT = 4, >> >> BT_EVENT_FIELDS = 5, >> >> >> >> I could not figure out the way to ready the fields 'id' and >> >> 'stream_id', for a particular event while iterating through the trace. >> >> Though I can ready the event name using an API and fields using >> >> BT_EVENT_FIELDS as a scope. >> >> For e.g. consider the >> >> >> >> event { >> >> name = sched_migrate_task; >> >> id = 1; >> >> stream_id = 0; >> >> fields := struct { >> >> integer { size = 8; align = 8; signed = 1; encoding = >> >> UTF8; base = 10; } _comm[16]; >> >> integer { size = 32; align = 8; signed = 1; encoding = >> >> none; base = 10; } _tid; >> >> integer { size = 32; align = 8; signed = 1; encoding = >> >> none; base = 10; } _prio; >> >> integer { size = 32; align = 8; signed = 1; encoding = >> >> none; base = 10; } _orig_cpu; >> >> integer { size = 32; align = 8; signed = 1; encoding = >> >> none; base = 10; } _dest_cpu; >> >> }; >> >> }; >> >> >> > >> > The "id" field is part of the BT_STREAM_EVENT_HEADER scope, while >> > the "stream_id" field is part of the BT_TRACE_PACKET_HEADER scope. >> > >> > The code below is adapted from converter/babeltrace.c's >> > convert_trace() loop to print both values. >> > >> > while ((ctf_event = bt_ctf_iter_read_event(iter))) { >> > >> > const struct bt_definition *stream_event_header_scope = >> > bt_ctf_get_top_level_scope( >> > ctf_event, BT_STREAM_EVENT_HEADER); >> > const struct bt_definition *id_field = >> > bt_ctf_get_field( >> > ctf_event, stream_event_header_scope, >> > "id"); >> > >> > printf("id = %" PRIu64 "\n", bt_ctf_get_uint64(id_field)); >> > >> > const struct bt_definition *packet_header_scope = >> > bt_ctf_get_top_level_scope( >> > ctf_event, BT_TRACE_PACKET_HEADER); >> > const struct bt_definition *stream_id_field = >> > bt_ctf_get_field( >> > ctf_event, packet_header_scope, >> > "stream_id"); >> > >> > printf("stream_id = %" PRIu64 "\n", bt_ctf_get_uint64( >> > stream_id_field)); [...] } >> > >> > Regards, >> > Jérémie >> > >> >> >> >> Any help or suggestion related to this issue will be really appreciated. >> >> Thanks! >> >> >> >> Regards, >> >> Salman >> >> >> >> -- >> >> Salman Rafiq >> >> Geschäftsfeld Industrial Communication Fraunhofer-Institut für >> >> Eingebettete Systeme und Kommunikationstechnik ESK >> >> >> >> Hansastraße 32 | 80686 München >> >> Telefon, Fax: +49 89 547088-356 | +49 89 547088-221 >> >> E-Mail: [email protected] >> >> >> >> Internet: >> >> http://www.esk.fraunhofer.de >> >> http://www.twitter.com/FraunhoferESK >> >> >> > >> > >> > >> > -- >> > Jérémie Galarneau >> > EfficiOS Inc. >> > http://www.efficios.com >> >> >> >> -- >> Jérémie Galarneau >> EfficiOS Inc. >> http://www.efficios.com >> > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com -- Jérémie Galarneau EfficiOS Inc. http://www.efficios.com _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
