Support for ITIMER_PROF?

[Ken Brown]

On 6/22/2015 9:25 AM, Corinna Vinschen wrote:
> On Jun 22 08:05, Ken Brown wrote:
>> According to the Cygwin API documentation
>> (https://cygwin.com/cygwin-api/std-notes.html), "getitimer and setitimer
>> only support ITIMER_REAL for now."  I'm wondering whether there's any chance
>> that support for ITIMER_PROF might be added.  I have no idea what the
>> obstacles are.
>>
>> My reason for asking is that emacs has a CPU profiling function, which
>> doesn't work on Cygwin because it relies on ITIMER_PROF.  (There's an
>> alternative implementation, but it requires timer_getoverrun, also not
>> available in Cygwin.)
>
> Both very tricky.  Given the description of timer_getoverrun and how
> this stuff is implemented in Cygwin, you might get away with
>
>    #ifdef __CYGWIN__
>    #define timer_getoverrun(x)	0
>    #endif
>
> indepedently of using SIGEV_SIGNAL or SIGEV_THREAD.

This seems to work.  Thanks!

One question: It seems that SIGEV_SIGNAL and friends are defined as macros on 
Linux (or at least on the one Linux distribution I looked at), but on Cygwin 
they're only enum constants.  And emacs expects them to be defined as macros. 
Would something like the following be reasonable for the sake of compatibility?

--- a/winsup/cygwin/include/cygwin/signal.h
+++ b/winsup/cygwin/include/cygwin/signal.h
@@ -311,6 +311,10 @@ enum
                                            perform notification */
  };

+#define SIGEV_SIGNAL SIGEV_SIGNAL
+#define SIGEV_NONE   SIGEV_NONE
+#define SIGEV_THREAD SIGEV_THREAD
+
  #if __WORDSIZE == 64
  typedef __uint64_t sigset_t;
  #else


Ken
Ken

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