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Re: [PATCH 07/10] Add __pthread_set_abort_hook export


On Wed, Jan 16, 2013 at 06:42:25PM +0100, Torvald Riegel wrote:
> On Fri, 2013-01-11 at 23:33 +0100, Andi Kleen wrote:
> > On Fri, Jan 11, 2013 at 10:23:50PM +0100, Torvald Riegel wrote:
> > > On Thu, 2013-01-10 at 12:19 -0800, Andi Kleen wrote:
> > > > From: Andi Kleen <ak@linux.intel.com>
> > > > 
> > > > For some debugging scenarios it is useful to catch aborts. Looking
> > > > at the abort code can be the only way to get information out of a
> > > > memory transaction.
> > > 
> > > If it's purely for debugging purposes through external debugging tools,
> > > a systemtap probe or something similar might also be sufficient (or
> > > better).
> > 
> > It's not. Out of band monitoring is very different from in-band.
> 
> So what's the in-band monitoring use case?

Transaction aware assert. Out of band monitoring is generally done with
PMU profilers like perf using PEBS records.

https://github.com/andikleen/tsx-tools/blob/master/README.txn-assert


> 
> And yes, what you implement is the concept of eliding locks using HW
> help, so I'd use the hardware lock elision name coined for this concept.

In the context of TSX HLE means XACQUIRE/XRELEASE prefixes. Since these
are not used in the glibc implementation calling the glibc
implementation HLE is not appropiate.

I can rename the hook __pthread_set_elision_abort_hook_np, although
I personally think that name is too long.

-Andi


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