Subject: Re: [patch 4/4] KVM-trace port to tracepoints
From: Peter Zijlstra <peterz@infradead.org>
To: Avi Kivity <avi@qumranet.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>,
       Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
       akpm@linux-foundation.org, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
       "Feng(Eric) Liu" <eric.e.liu@intel.com>
In-Reply-To: <48862B01.7070907@qumranet.com>
References: <20080717155724.897537670@polymtl.ca>
	 <20080717160003.359557938@polymtl.ca> <487F7800.4010502@siemens.com>
	 <20080717172853.GB29855@Krystal> <488604F8.1040008@siemens.com>
	 <48862B01.7070907@qumranet.com>
Content-Type: text/plain
Date: Wed, 23 Jul 2008 09:49:06 +0200
Message-Id: <1216799346.7257.125.camel@twins>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 942
Lines: 21

On Tue, 2008-07-22 at 21:46 +0300, Avi Kivity wrote:
> Jan Kiszka wrote:
> > That's true - as long as you don't have to add/remove/modify
> > tracepoints. I had to do this job in the past (not for KVM). Having 1
> > spot in 1 file (based on generic probes) would be handier in that case
> > than 5 spots in 3 files. But if the KVM tracepoints are considered
> > stable in their number and structure, that shouldn't be an issue here.
> >
> >   
> 
> Tracepoints aren't stable; they are artefacts of the implementation.

Which IMHO makes it unsuitable for trace_mark() as that will be exported
to user-space, and every time you change your tracepoints you'll change
user visible things - not nice.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/