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Re: [PATCH] Linux Kernel Markers 0.13 for 2.6.17
- From: Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>
- To: Jeremy Fitzhardinge <jeremy at goop dot org>
- Cc: Martin Bligh <mbligh at google dot com>, "Frank Ch. Eigler" <fche at redhat dot com>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, prasanna at in dot ibm dot com, Andrew Morton <akpm at osdl dot org>, Ingo Molnar <mingo at elte dot hu>, Paul Mundt <lethal at linux-sh dot org>, linux-kernel <linux-kernel at vger dot kernel dot org>, Jes Sorensen <jes at sgi dot com>, Tom Zanussi <zanussi at us dot ibm dot com>, Richard J Moore <richardj_moore at uk dot ibm dot com>, Michel Dagenais <michel dot dagenais at polymtl dot ca>, Christoph Hellwig <hch at infradead dot org>, Greg Kroah-Hartman <gregkh at suse dot de>, Thomas Gleixner <tglx at linutronix dot de>, William Cohen <wcohen at redhat dot com>, ltt-dev at shafik dot org, systemtap at sources dot redhat dot com, Alan Cox <alan at lxorguk dot ukuu dot org dot uk>, Karim Yaghmour <karim at opersys dot com>, Pavel Machek <pavel at suse dot cz>, Joe Perches <joe at perches dot com>, "Randy.Dunlap" <rdunlap at xenotime dot net>, "Jose R. Santos" <jrs at us dot ibm dot com>
- Date: Mon, 25 Sep 2006 20:25:51 -0400
- Subject: Re: [PATCH] Linux Kernel Markers 0.13 for 2.6.17
- References: <20060925233349.GA2352@Krystal> <20060925235617.GA3147@Krystal> <email@example.com>
* Jeremy Fitzhardinge (firstname.lastname@example.org) wrote:
> Mathieu Desnoyers wrote:
> >Just as a precision :
> >The following sequence (please refer to the code below for local symbols
> >1 and 2) :
> >call (*__mark_call_##name)(format, ## args);
> >is insured because :
> >1 is part of an inline assembly with rw dependency on __marker_sequencer
> >the call is surrounded by memory barriers.
> >2 is part of an inline assembly with rw dependency on __marker_sequencer
> What do you mean the call is surrounded by memory barriers? Do you mean
> a call has an implicit barrier, or something else?
Yes, preempt_disable() has a barrier(), on gcc :
__asm__ __volatile__("": : :"memory").
> Either way, this doesn't prevent some otherwise unrelated
> non-memory-using code from being scheduled in there, which would not be
> executed. The gcc manual really strongly discourages jumping between
> inline asms, because they have basically unpredictable results.
Ok, I will do the call in assembly then.
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