IIRC there is an alternative to futex for synchronization that can provide 64 bit locks. It's implemented as a multiple object wait system mainly for wine? (WaitForMultipleObjects?).<br><br>I think that system can be used for single object waits as well.<br><br><br>Sent from ProtonMail mobile<br><br><br><br>-------- Original Message --------<br>On Aug 24, 2021, 12:32, Thiago Macieira via Std-Proposals < std-proposals@lists.isocpp.org> wrote:<blockquote class="protonmail_quote"><br><p dir="ltr">On Tuesday, 24 August 2021 00:01:53 PDT Marko M&#228;kel&#228; via Std-Proposals wrote:<br>
&gt; Good points. I thought that having this in the standard library would<br>
&gt; create more pressure to operating system developers to provide some<br>
&gt; futex-like functionality.</p>
<p dir="ltr">Linux, Windows and Darwin have it, though for Darwin it doesn't appear to be<br>
documented. Your code has shown OpenBSD does too, something I didn't know.<br>
FreeBSD definitely has it for its Linux-compatibility layer, but I don't know<br>
if that has been exposed to the FreeBSD native ABI (just as eventfd hasn't).</p>
<p dir="ltr">I don't think the standard library can force that much. We'd end up with the<br>
opposite: the futex functionality is emulated by way of locks. An example is<br>
Linux itself: Linus is quite against extending the futex functionality to 64-<br>
bit values, so std::atomic&lt;int64_t&gt;::wait will likely remain emulated on Linux<br>
for a long time.</p>
<p dir="ltr">If this was your reason, please re-evaluate.</p>
<p dir="ltr">--<br>
Thiago Macieira - thiago (AT) <a href="http://macieira.info">macieira.info</a> - thiago (AT) <a href="http://kde.org">kde.org</a><br>
Software Architect - Intel DPG Cloud Engineering<br><br></p>
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