[RFC] Lock elision implementation guidelines

[Dominik Vogt]

On Tue, Jun 11, 2013 at 04:07:26PM -0700, Andi Kleen wrote:
> Dominik Vogt <vogt@linux.vnet.ibm.com> writes:
> >
> > The attached program suffers from a massive performance loss
> > caused by lock elision.
> 
> FWIW with TSX the difference between elision/no elision for your
> test is within the measurement inaccuracy.

It probably depends on the hardware implementation details of the
HTM system.  The idea of the test program was to "break" a HTM
that aborts a transaction that writes a memory cell if that cell
is read afterwards from another transaction or outside a
transaction.  This is the case for the zEC12, but I don't know the
details of TSX very well, and I only have access to a
z/architecture machine.  Is there any document available where I
can look up the TSX implementation details?  

(And although the test program does suffer from a substantial
slowdown on the zEC12, the explanation for that might be different
from what I thought.)

Ciao

Dominik ^_^  ^_^

-- 

Dominik Vogt
IBM Germany