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Date: Tue, 19 Oct 2010 15:41:36 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
cc: Koki Sanagi <sanagi.koki@jp.fujitsu.com>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>,
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        Heiko Carstens <heiko.carstens@de.ibm.com>,
        "Luck, Tony" <tony.luck@intel.com>
Subject: Re: [PATCH] tracing: Cleanup the convoluted softirq tracepoints
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On Tue, 19 Oct 2010, Mathieu Desnoyers wrote:

> * Thomas Gleixner (tglx@linutronix.de) wrote:
> > With the addition of trace_softirq_raise() the softirq tracepoint got
> > even more convoluted. Why the tracepoints take two pointers to assign
> > an integer is beyond my comprehension.
> > 
> > But adding an extra case which treats the first pointer as an unsigned
> > long when the second pointer is NULL including the back and forth
> > type casting is just horrible.
> > 
> > Convert the softirq tracepoints to take a single unsigned int argument
> > for the softirq vector number and fix the call sites.
> 
> Well, there was originally a reason for this oddness. The in __do_softirq(),
> "h - softirq_ve"c computation was not needed outside of the tracepoint handler
> in the past, but it now seems to be required with the new inlined
> "kstat_incr_softirqs_this_cpu()".

Dudes, a vector computation is hardly a performance problem in that
function and definitely not an excuse for designing such horrible
interfaces.

Thanks,

	tglx