RE: Control Dependencies vs C Compilers

David Laight
2020-10-06T16:22:17Z

From: Willy Tarreau
> Sent: 06 October 2020 17:11
>
> On Tue, Oct 06, 2020 at 08:50:52AM -0700, Paul E. McKenney wrote:
> > Comparing 25+ assembly languages to but two compilers most definitely
> > motivates looking hard at doing something with the compilers.
>
> +1, especially since the kernel is not special; anyone working with
> threads faces the same issues in userland, which are often hidden
> behind the implicit whole-memory clobbers of certain operations or
> the call to mutex manipulation functions, but which become a reality
> again as soon as you go slightly away from these and try to use
> lockless mechanisms.

AFAICT most windows and android apps completely ignore the problem
of thread locking - which is why the crash and lock up all the time :-)

I've spent most of the day looking at some library traces from a
customer bug.
I almost suspect a bug in the pthread mutex code on their system.
They are using a nice, modern, 3.10.0-957.el7.x86_64 kernel.

David

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