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

[Ken Brown <kbrown@cornell.edu>]

On 6/22/2015 4:00 AM, Sebastien Vauban wrote:
> Ken Brown <kbrown@cornell.edu> writes:
>> On 6/21/2015 10:56 AM, Eli Zaretskii wrote:
>>>> Date: Sat, 20 Jun 2015 17:47:21 -0400
>>>> From: Ken Brown <kbrown@cornell.edu>
>>>> CC: sva-news@mygooglest.com, 20843@debbugs.gnu.org
>>>>
>>>>> 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?
>>>
>>> Actually, perhaps I misunderstood you: are you saying that Cygwin does
>>> have ITIMER_PROF defined in the appropriate header, but when setitimer
>>> is called with it, it always fails?
>>
>> Yes.
>>
>>> If so, we cannot test this at
>>> configure time, because it means we will have to run a program, which
>>> is not a good idea.
>>>
>>> So in that case, I think we should simply disable the CPU profiler on
>>> Cygwin using "#ifndef __CYGWIN__" or some such.
>>
>> Done as commit 5fac0de.
>>
>>>>>    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.
>>>
>>> Yes, please.
>
> For me to understand, does this mean we never will be able to start the
> profiler under Cygwin Emacs?

I wouldn't say "never".  According to the Cygwin API documentation 
(https://cygwin.com/cygwin-api/std-notes.html), "getitimer and setitimer only 
support ITIMER_REAL for now."  I'll ask on the Cygwin list about the possibility 
of supporting ITIMER_PROF.

Ken
>