linux-kernel - Re: [PATCH 15/15] perf, tools: Add perf stat --transaction v3

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Date:	Thu, 27 Jun 2013 05:49:11 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Michael Ellerman <michael@...erman.id.au>
Cc:	Andi Kleen <andi@...stfloor.org>, mingo@...e.hu, acme@...hat.com,
	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	mlpesant@...ibm.com
Subject: Re: [PATCH 15/15] perf, tools: Add perf stat --transaction v3

> OK. I'm still confused by that one sorry. In the patch you do:
> 
> +       else if (perf_evsel__cmp(counter, nth_evsel(T_CYCLES_IN_TX_CP)))
> +               update_stats(&runtime_cycles_in_txcp_stats[0], count[0]);
> 
> But then I don't see where you use runtime_cycles_in_txcp_stats ?

You're right that variable is not needed. I'll remove it. 
It only needs the in_tx stat.

intx-cp is still output, but directly by abs_printout,
without going through a variable.

> 
> > > But I don't think we have anything equivalent.
> > 
> > But you have cycles-t and tx-start?
> 
> We have:
>  - cycles
>  - cycles in transactional state
>  - cycles spent in successful transactions
> 
> So your cycles-t is "cycles in transactional state".
> 
> We would calculate cycles wasted in aborts with:
> 
>  "cycles in transactional" - "cycles in successful transactions"
> 
> Which I think is what you're describing above with cycles-ct.

Yes, that should be equivalent.
That should be easy to check for and handle: check for that 
event and switch the formula around.
I'll leave that to you as I don't have any way to test it.

> Does "tx-start" just count the number of transactions begun? Does it
> count nested transactions?

Just begun without nesting (TSX flattens all transactions)

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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