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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.