[m-rev.] For review: Workaround Linux NTPL TSX bug (Mercury Bug: 334)

[Peter Wang]

On Fri, 27 Jun 2014 16:18:26 +1000, Paul Bone <paul at bone.id.au> wrote:
> On Fri, Jun 27, 2014 at 03:33:46PM +1000, Peter Wang wrote:
> > On Fri, 27 Jun 2014 11:27:40 +1000, Paul Bone <paul at bone.id.au> wrote:
> > > 
> > > Of course my change here is only a workaround.  The real fix is patching
> > > glibc.
> > 
> > Well, I prefer you do not commit it.  If it's just to continue your
> > development, I think you could rebuild glibc with --disable-lock-elision
> > and LD_PRELOAD libpthread?
> 
> What if other users have the same error?  This affects all
> asm_fast.gc.par.stseg grades.  I can't resonably ask other users, including
> yourself, either to buy a processor without this extension or to always use
> an older version of glibc.

I guess I'm expecting that it to be fixed one way or another, in due
time, if more popular Boehm GC-using software is affected.

> > Otherwise, from what I can tell, calling pthread_mutexattr_settype with
> > PTHREAD_MUTEX_DEFAULT (or maybe PTHREAD_MUTEX_NORMAL) is enough to
> > disable lock elision, which is the same type of mutex as for
> > PTHREAD_MUTEX_INITIALIZER.  You don't need to test the glibc version.
> 
> Are you saying that PTHREAD_MUTEX_DEFAULT and/or PTHREAD_MUTEX_NORMAL also
> disable elision?

PTHREAD_MUTEX_DEFAULT for glibc-2.19
http://repo.or.cz/w/glibc.git/commit/49186d21ef2d87986bccaf0a7c45c48c91b265f3
PTHREAD_MUTEX_NORMAL for unreleased versions
http://repo.or.cz/w/glibc.git/commit/673659263d956f45f1ce0c66900fa7f1129db74a

Peter