Em Thu, Sep 11, 2014 at 12:27:26PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Sep 11, 2014 at 05:09:43PM +0200, Jiri Olsa escreveu:
> > > + fcntl(fd, F_SETFL, O_NONBLOCK);
> >
> > also I spot this one and couldn't think of reason for it, attached
> > patch makes no behaviour difference for me..
>
> Have to look why it is there, perhaps there is some changeset
> specifically made for this, will do some research...
>
> > I might be missing something, but I dont see any blocking operation
> > in perf related data reads. The git log history says it was there
> > since early days.
>
> Oops, you did that research already, have you followed the history all
> the way to when this code lived in Documentation/ ?
Since day one, found using:
$ git log -p --follow tools/perf/builtin-top.c
commit e0143bad9dbf2a8fad4c5430562bceba196b66ea
Author: Ingo Molnar <mi...@elte.hu>
Date: Mon Mar 23 21:29:59 2009 +0100
perf_counter: add sample user-space to Documentation/perf_counter/
Initial version of kerneltop.c and perfstat.c.
Acked-by: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Paul Mackerras <pau...@samba.org>
Signed-off-by: Ingo Molnar <mi...@elte.hu>
diff --git a/Documentation/perf_counter/kerneltop.c
b/Documentation/perf_counter/kerneltop.c
Ingo, do we really need that O_NONBLOCK thing there?
- Arnaldo
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