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Re: [PATCH v3 0/6] Add support for ISO C11 threads.h
- From: Torvald Riegel <triegel at redhat dot com>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- Cc: Martin Sebor <msebor at gmail dot com>, Joseph Myers <joseph at codesourcery dot com>, libc-alpha at sourceware dot org, Martin Sebor <msebor at redhat dot com>, Stefan Liebler <stli at linux dot vnet dot ibm dot com>
- Date: Thu, 06 Apr 2017 13:05:08 +0200
- Subject: Re: [PATCH v3 0/6] Add support for ISO C11 threads.h
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On Fri, 2017-03-31 at 10:39 -0300, Adhemerval Zanella wrote:
>
> On 28/03/2017 05:08, Torvald Riegel wrote:
> > On Mon, 2017-03-27 at 10:10 -0600, Martin Sebor wrote:
> >> I've reviewed the DRs and your comments below. I agree with
> >> your view and just for clarity provide some additional comments
> >> of my own.
> >
> > Thanks!
> >
> >> There's been a lot of talk over the last few WG14 meetings about
> >> the whole threads section needing an overhaul. I don't know if
> >> anyone is actually working on it but if it were to happen (for
> >> C2X) there is some risk that an implementation coded to the C11
> >> spec not conforming to the cleaned up and improved C2X spec.
> >
> > I'd hope that they wouldn't deviate from what C++ specifies. I'm
> > monitoring C++ changes, including whether anything would result in
> > required changes for glibc. IOW, if C doesn't deviate from C++, we
> > shouldn't need additional changes just for C.
> >
>
> Thanks for both extensive inputs and discussion. From the comments I
> see that a current C11 thread based on POSIX could be still be feasible,
> however I am not sure if we should prevent its implementation based on
> the C2X possible different spec.
>
> In any way, I see that the still pending DR493 should not pose any
> implementation issues (we can work out on the wrapper if any other
> requirement is posed).
>
> So I would like the input from the community whether implementing C11
> in GLIBC is desirable and if current approach based is most correct
> one.
I think it is desirable, and it's probably about time that we have
something. I'm not aware of anything that would be a huge problem. C11
is in several cases much closer to what we implement than POSIX.
I still think it may have been nice to have smaller data structure sizes
for things like mutexes; however, we don't have consensus in the
community to shrink them, and we don't have the resources I believe to
really investigate this.
I haven't looked at the TLS issues, or at how you organize headers and
such. I also haven't yet reviewed all of your patches. But unless
somebody complains, IMHO we should just go forward with what you have.
Supporting the C11 threading support functions in the next release would
be nice.