From: Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups: fa.linux.kernel
Subject: Re: [ANNOUNCE] mdb: Merkey's Linux Kernel Debugger 2.6.27-rc4
Date: Thu, 21 Aug 2008 15:59:16 UTC
Message-ID: <fa.rk3/z/KZsL4Nrc3SZHdm8sUxVfg@ifi.uio.no>

On Thu, 21 Aug 2008, Paul E. McKenney wrote:
>
> Let's face it, the C standard does not support concurrency, so we are
> all in a state of sin in any case, forced to rely on combinations of
> gcc-specific non-standard language extensions and assembly language.
>
> Could be worse!!!

It _will_ be worse.

The C standard will eventually support concurrency (they are working on
it), and it will almost inevitably be a horrible pile of stinking sh*t,
and we'll continue to use the gcc inline asms instead, but then the gcc
people will ignore our complaints when they break the compiler, and say
that we should use the stinking-pile-of-sh*t ones that are built in.

No, I haven't seen the drafts, and maybe I'm overly pessimistic, but I'm
pretty sure that this is an area where (a) the kernel needs more support
than most normal pthread-like models and (b) any design-by-committee thing
simply won't be very good, because they'll have to try to make everybody
happy.

Oh, well.

		Linus

From: Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups: fa.linux.kernel
Subject: Re: [ANNOUNCE] mdb: Merkey's Linux Kernel Debugger 2.6.27-rc4
Date: Thu, 21 Aug 2008 16:20:36 UTC
Message-ID: <fa.vHgx9bIp+7mclM9fwZo/x/MRX8U@ifi.uio.no>

On Thu, 21 Aug 2008, Linus Torvalds wrote:
>
> No, I haven't seen the drafts

Ok, I have looked at the draft now, and I don't think I was overly
pessimistic.

If I read it right, all the memory ordering operations are defined for
_single_ objects. So if you want to do the kernel kind of memory ordering
where you specify ordering requirements independently of the actual
accesses (perhaps because the accesses are in some helper function that
doesn't care, but then you want to "finalize" the thing by stating a
sequence point), it seems to be impossible with current drafts.

Oh, well. Nothing lost. I didn't expect the thing to work.

		Linus