bug#20843: 24.5; Profiler error: "Invalid sampling interval"

[Ken Brown <kbrown@cornell.edu>]

On 6/20/2015 3:10 PM, Eli Zaretskii wrote:
>> Date: Sat, 20 Jun 2015 15:02:28 -0400
>> From: Ken Brown <kbrown@cornell.edu>
>> CC: 20843@debbugs.gnu.org
>>
>> On 6/18/2015 4:57 AM, Eli Zaretskii wrote:
>>>> From: Sebastien Vauban <sva-news@mygooglest.com>
>>>> Date: Thu, 18 Jun 2015 10:37:02 +0200
>>>>
>>>> When trying to start the profiler under Cygwin Emacs 24.5, I get this:
>>>>
>>>> --8<---------------cut here---------------start------------->8---
>>>> Debugger entered--Lisp error: (error "Invalid sampling interval")
>>>>     profiler-cpu-start(1000000)
>>>>     profiler-start(cpu)
>>>>     call-interactively(profiler-start record nil)
>>>
>>> Can you step with GDB into setup_cpu_timer, and see what goes wrong
>>> there?  I suspect this portions:
>> [...]
>>
>> No, the problem is that Cygwin's setitimer supports only ITIMER_REAL, so
>> the call to setitimer(ITIMER_PROF,...) in profiler.c:315 fails.
>
> Then I guess the configure-time test for setitimer should also test
> for ITIMER_PROF.

I'd be glad to give this a try, but I don't have any experience writing 
autoconf macros.  Is there a standard macro to test whether a function 
accepts a particular argument?  If not, can you (or anyone) point me to 
an example that I can imitate?

>  Also, the diagnostics should be improved, as the
> wording is misleading in that case.

As it stands, profiler-cpu-start reports "Invalid sampling interval" 
whenever setup_cpu_timer fails to start the timer, regardless of the 
reason.  I'll try to improve this.

Ken