2013-11-27 (수), 11:41 -0300, Arnaldo Carvalho de Melo: > Em Wed, Nov 27, 2013 at 11:17:43PM +0900, Namhyung Kim escreveu: > > 2013-11-27 (수), 10:44 -0300, Arnaldo Carvalho de Melo: > > > Same signature, 32-bit, 64-bit userland, so whoever wrote timechart, > > > Arjan, I > > > think, made no mistakes at using the kernel exported interface, choosing > > > the > > > most efficient way to extract the data, casting to a struct. > > > > Yeah, using the interface that searches for a field name to get the > > > offset and > > > then add it to a pointer to then cast to the type will allow maximum > > > flexibility, > > > but is not really efficient. > > > > Doing that for something that is not performance critical (probably) as > > > timechart probably is not a problem, but so is not a problem using the > > > patch > > > that does the cast after finding the offset of the first non-common field. > > > I'm not sure how it affects the performance really. > > Hey, everytime we need to get the value of a field when processing each > tracepoint sample we need to do it via: > > struct format_field *pevent_find_field(struct event_format *event, const char > *name) > { > struct format_field *format; > > for (format = event->format.fields; format; format = format->next) { > if (strcmp(format->name, name) == 0) > break; > } > > return format; > } > > I don't think this is optimal, no. > > But yeah, for things that don't have performance needs, don't process that > many > samples and hey, machines are fast and cheap these days ;-)
Right. What I wanted to say actually was like s/how/how much/. :) Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/