linux-kernel - Re: [PATCH] tracing: Cleanup the convoluted softirq tracepoints

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Message-ID: <alpine.LFD.2.00.1010191558250.6815@localhost6.localdomain6>
Date:	Tue, 19 Oct 2010 16:07:09 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Steven Rostedt <rostedt@...dmis.org>
cc:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Koki Sanagi <sanagi.koki@...fujitsu.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	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, Steven Rostedt wrote:

> On Tue, 2010-10-19 at 15:41 +0200, Thomas Gleixner wrote:
> > On Tue, 19 Oct 2010, Mathieu Desnoyers wrote:
> 
> > Dudes, a vector computation is hardly a performance problem in that
> > function and definitely not an excuse for designing such horrible
> > interfaces.
> 
> Yes, now we can be a bit more liberal. But when these tracepoints were
> going in, people were watching to make sure they have practically zero
> impact when tracing was disabled.
> 
> Now that people are more use to tracepoints, they are more understanding
> to have cleaner code over that extra few more lines of machine code in
> the fast path.

The vector computation is compared to the extra tracing induced jumps
probably not even measurable. Stop defending horrible coding with
handwavy performance and impact arguments.

Thanks,

	tglx
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