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Message-ID: <alpine.LFD.2.00.1010191524160.6815@localhost6.localdomain6>
Date: Tue, 19 Oct 2010 15:41:36 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
cc: Koki Sanagi <sanagi.koki@...fujitsu.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...e.hu>,
Frederic Weisbecker <fweisbec@...il.com>,
Steven Rostedt <rostedt@...dmis.org>, nhorman@...driver.com,
scott.a.mcmillan@...el.com, laijs@...fujitsu.com,
"H. Peter Anvin" <hpa@...or.com>,
LKML <linux-kernel@...r.kernel.org>, eric.dumazet@...il.com,
kaneshige.kenji@...fujitsu.com, David Miller <davem@...emloft.net>,
izumi.taku@...fujitsu.com, kosaki.motohiro@...fujitsu.com,
Heiko Carstens <heiko.carstens@...ibm.com>,
"Luck, Tony" <tony.luck@...el.com>
Subject: Re: [PATCH] tracing: Cleanup the convoluted softirq tracepoints
On Tue, 19 Oct 2010, Mathieu Desnoyers wrote:
> * Thomas Gleixner (tglx@...utronix.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
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