Messages in this thread | | | Date | Fri, 30 May 2008 20:14:35 -0700 | From | Ulrich Drepper <> | Subject | Re: [PATCH 0/3] 64-bit futexes: Intro |
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Linus Torvalds wrote: > We've had a 32-bit rwsemaphore in the kernel for a *long* time.
You misread what I wrote.
Semaphores are fine. The problem are reader/writer locks where we need three counters and some flags. It is absolutely not acceptable to limit the number of threads to 512 to make this fit.
> I think it's totally stupid for glibc to even *try* to do something like > this, since almost nobody will have a kernel with 64-bit futex support for > a long time in the wild anyway. So you need to support a 32-bit semaphore > in practice, and it's been done before.
Again, misread. This is not functionality which is not available. Semaphores are *of course* fine with 32 bits. And there is a reader/writer lock implementation. It is just very slow compared to what is possible. The transition between systems miss the 64-bit support and those which have it is completely transparent. The same glibc binary will work for both.
- -- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux)
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