Re: perf trace errors

Frederic Weisbecker
2009-10-11T20:24:39Z

On Sun, Oct 11, 2009 at 02:40:30PM +0200, Christoph Hellwig wrote:
> On Sun, Oct 11, 2009 at 02:19:28PM +0200, Frederic Weisbecker wrote:
> > Yeah, there are still some trace events that are not well supported
> > in perf trace, for now... I'll fix that by the time.
>
> Any idea what is the missing part? I tried to understand the code but
> I haven't even managed to grasp the data structures yet.
>
> The weird thing is that these message seem to come from parsing of
> the filters, and a simple trace the whole system trace shouldn't
> really have to set any filters anyway, nor should the filters depdend
> on what trace point you use.
>
> Note that the in addition to all the block trace points also all my
> new xfs tracepoints also give errors from perf trace. Things tend
> to work quite nicely with the ASCII output from the kernel.
>

It's about the trace event format file parsing, especially the format
line:

print fmt: "%d,%d %s %llu + %u [%s]", ((unsigned int) ((REC->dev) >> 20)), ((unsigned int) ((REC->dev) & ((1U << 20)
- 1))), REC->rwbs, (unsigned long long)REC->sector, REC->nr_sector, REC->comm

This is done from tools/perf/util/trace-event-parse.c

It is supposed to handle such cases already, not sure exactly where is
the problem currently, that needs some investigation.