Re: gprof question

[Kilgallen@eisner.decus.org.nospam (Larry Kilgallen)]

In article <9hpdkf$nhb$1@s1.read.news.oleane.net>, "Jean-Pierre Rosen" <rosen@adalog.fr> writes:
> I have a multi-tasks, IO intensive program that I ran under gprof to identify bottlenecks (GNAT 3.13p under Win95).
> Although the (real) execution time is about 3mn 30s, gprof shows only 6 samples (at 0.01s. period!).
> My explanation is that interrupts (and therefore gprof sampling) are suspended during IO suspension, and that all time spent in IO
> procedures escapes analysis. Is this correct ? It would be terribly annoying in my case...

You might consider whether the operating system in question has the
ability to wait for IO in the mode of the caller.  If it does not,
there is no way a user mode interrupt could come while you are
waiting for IO.

But I am not sure I know what "interrupts" are for a user mode
program on Windows or Linux.  On VMS the corresponding thing
might be "AST's" which certainly work when waiting for IO
(unless GNAT does something quite wrong).  Perhaps trying
it on VMS would get you "close-enough" profile results to
the real answers for Windows.