← Back to team overview

maria-developers team mailing list archive

Re: Memory barrier problem in InnoDB/XtraDB mutex implementation causing hangs


Kristian Nielsen <knielsen@xxxxxxxxxxxxxxx> writes:

> So you may be right that the implementation needs no explicit full memory
> barrier in theory...
> On the other hand, I have implemented code that _does_ assume a full barrier
> for each operation individually (see

I checked glibc sources for powerpc. They seem to have only acquire barrier
for pthread_mutex_lock(), and only release barrier for pthread_mutex_unlock(),
assuming I read the code correctly.

So looks like I am wrong to think that a full barrier is necessarily implied
by pthread_mutex_lock() alone (or pthread_mutex_unlock() alone). I will need
to review my earlier code to check for this. Well, usually in fact only the
acquire / release is sufficient, but I'll need to check.


 - Kristian.