| Message ID | 20210811121203.29123-5-y.karadz@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | libtraceevent: Optimize the print of tep fields | expand |
On Wed, 11 Aug 2021 15:12:02 +0300 "Yordan Karadzhov (VMware)" <y.karadz@gmail.com> wrote: > The current implementation of tep_print_fields() loops over all > individual fields of the event and calls tep_print_field() for > each one. In the same time inside tep_print_field() we loop over > the list of all tokens of the printing format descriptor in order > to determine how the current field must be printed (its own > appropriate printing format). The problem is that in this second > loop over the tokens we always start from the very first token > and this can be quite inefficient for example in a case of a > kprobe that has a large number of fields. This patch optimizes > tep_print_fields(), allowing the traverse of the list of tokens > to continue from the place reached when we searched for the > format of the previous field. > > Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com> > --- > src/event-parse.c | 30 +++++++++++++++++++++++------- > 1 file changed, 23 insertions(+), 7 deletions(-) > > diff --git a/src/event-parse.c b/src/event-parse.c > index 9399555..7831e74 100644 > --- a/src/event-parse.c > +++ b/src/event-parse.c > @@ -5392,14 +5392,15 @@ static void tep_print_field_raw(struct trace_seq *s, void *data, > static int print_parse_data(struct tep_print_parse *parse, struct trace_seq *s, > void *data, int size, struct tep_event *event); > > -void tep_print_field(struct trace_seq *s, void *data, > - struct tep_format_field *field) > +void static inline _tep_print_field(struct trace_seq *s, void *data, > + struct tep_format_field *field, > + struct tep_print_parse **parse_ptr) > { > struct tep_event *event = field->event; > struct tep_print_parse *parse; > bool has_0x; > > - parse = event->print_fmt.print_cache; > + parse = parse_ptr ? *parse_ptr : event->print_fmt.print_cache; > > if (event->flags & TEP_EVENT_FL_FAILED) > goto out; > @@ -5407,7 +5408,7 @@ void tep_print_field(struct trace_seq *s, void *data, > if (field->flags & (TEP_FIELD_IS_ARRAY || TEP_FIELD_IS_STRING)) > goto out; > > - for (;parse; parse = parse->next) { > + while (parse) { If the parse field is not found, this will loop forever. We need this: struct tep_print_parse *start_parse; start_parse = parse; do { > if (parse->type == PRINT_FMT_STRING) { > int len = strlen(parse->format); > > @@ -5417,21 +5418,29 @@ void tep_print_field(struct trace_seq *s, void *data, > else > has_0x = false; > > - continue; > + goto next; > } > > if (!parse->arg || > parse->arg->type != TEP_PRINT_FIELD || > parse->arg->field.field != field) { > has_0x = false; > - continue; > + goto next; > } > > if (has_0x) > trace_seq_puts(s, "0x"); > > print_parse_data(parse, s, data, field->size, event); > + > + if (parse_ptr) > + *parse_ptr = parse->next; > + > return; > + > + next: > + parse = parse->next ? parse->next : > + event->print_fmt.print_cache; } while (parse != start_parse); -- Steve > } > > out: > @@ -5439,15 +5448,22 @@ void tep_print_field(struct trace_seq *s, void *data, > tep_print_field_raw(s, data, field); > } > > +void tep_print_field(struct trace_seq *s, void *data, > + struct tep_format_field *field) > +{ > + _tep_print_field(s, data, field, NULL); > +} > + > void tep_print_fields(struct trace_seq *s, void *data, > int size __maybe_unused, struct tep_event *event) > { > + struct tep_print_parse *parse = event->print_fmt.print_cache; > struct tep_format_field *field; > > field = event->format.fields; > while (field) { > trace_seq_printf(s, " %s=", field->name); > - tep_print_field(s, data, field); > + _tep_print_field(s, data, field, &parse); > field = field->next; > } > }
diff --git a/src/event-parse.c b/src/event-parse.c index 9399555..7831e74 100644 --- a/src/event-parse.c +++ b/src/event-parse.c @@ -5392,14 +5392,15 @@ static void tep_print_field_raw(struct trace_seq *s, void *data, static int print_parse_data(struct tep_print_parse *parse, struct trace_seq *s, void *data, int size, struct tep_event *event); -void tep_print_field(struct trace_seq *s, void *data, - struct tep_format_field *field) +void static inline _tep_print_field(struct trace_seq *s, void *data, + struct tep_format_field *field, + struct tep_print_parse **parse_ptr) { struct tep_event *event = field->event; struct tep_print_parse *parse; bool has_0x; - parse = event->print_fmt.print_cache; + parse = parse_ptr ? *parse_ptr : event->print_fmt.print_cache; if (event->flags & TEP_EVENT_FL_FAILED) goto out; @@ -5407,7 +5408,7 @@ void tep_print_field(struct trace_seq *s, void *data, if (field->flags & (TEP_FIELD_IS_ARRAY || TEP_FIELD_IS_STRING)) goto out; - for (;parse; parse = parse->next) { + while (parse) { if (parse->type == PRINT_FMT_STRING) { int len = strlen(parse->format); @@ -5417,21 +5418,29 @@ void tep_print_field(struct trace_seq *s, void *data, else has_0x = false; - continue; + goto next; } if (!parse->arg || parse->arg->type != TEP_PRINT_FIELD || parse->arg->field.field != field) { has_0x = false; - continue; + goto next; } if (has_0x) trace_seq_puts(s, "0x"); print_parse_data(parse, s, data, field->size, event); + + if (parse_ptr) + *parse_ptr = parse->next; + return; + + next: + parse = parse->next ? parse->next : + event->print_fmt.print_cache; } out: @@ -5439,15 +5448,22 @@ void tep_print_field(struct trace_seq *s, void *data, tep_print_field_raw(s, data, field); } +void tep_print_field(struct trace_seq *s, void *data, + struct tep_format_field *field) +{ + _tep_print_field(s, data, field, NULL); +} + void tep_print_fields(struct trace_seq *s, void *data, int size __maybe_unused, struct tep_event *event) { + struct tep_print_parse *parse = event->print_fmt.print_cache; struct tep_format_field *field; field = event->format.fields; while (field) { trace_seq_printf(s, " %s=", field->name); - tep_print_field(s, data, field); + _tep_print_field(s, data, field, &parse); field = field->next; } }
The current implementation of tep_print_fields() loops over all individual fields of the event and calls tep_print_field() for each one. In the same time inside tep_print_field() we loop over the list of all tokens of the printing format descriptor in order to determine how the current field must be printed (its own appropriate printing format). The problem is that in this second loop over the tokens we always start from the very first token and this can be quite inefficient for example in a case of a kprobe that has a large number of fields. This patch optimizes tep_print_fields(), allowing the traverse of the list of tokens to continue from the place reached when we searched for the format of the previous field. Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com> --- src/event-parse.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-)