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Date: Tue, 19 Oct 2010 21:36:30 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: Thomas Gleixner <tglx@...utronix.de> Cc: Jason Baron <jbaron@...hat.com>, 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 Wed, 2010-10-20 at 00:17 +0200, Thomas Gleixner wrote: > On Tue, 19 Oct 2010, Thomas Gleixner wrote: > > On Tue, 19 Oct 2010, Jason Baron wrote: > > > > Now even worse, when you NOP out the jmpq then your tracepoint is > > > > still not enabled. Brilliant ! > > > > > > > > > > The 'jmpq' in the enabled case is patched with a jmpq to the body of the > > > tracepoint itself. > > > > Brilliant. > > IOW, We now jump around the jump which jumps around the disabled code. > Do you happen to have CONFIG_CC_OPTIMIZE_FOR_SIZE set? If so, then this is a known issue. We even originally had jump label enabled _only_ if CC_OPTIMIZE_FOR_SIZE was not set, but hpa NAK'd it. http://lkml.org/lkml/2010/9/22/482 http://lkml.org/lkml/2010/9/20/488 http://lkml.org/lkml/2010/9/24/259 -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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