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Message-ID: <4886E6FD.4090200@qumranet.com>
Date: Wed, 23 Jul 2008 11:08:29 +0300
From: Avi Kivity <avi@...ranet.com>
To: Peter Zijlstra <peterz@...radead.org>
CC: Jan Kiszka <jan.kiszka@...mens.com>,
Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
akpm@...ux-foundation.org, Ingo Molnar <mingo@...e.hu>,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
"Feng(Eric) Liu" <eric.e.liu@...el.com>
Subject: Re: [patch 4/4] KVM-trace port to tracepoints
Peter Zijlstra wrote:
> 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.
>
They are used for debugging (mostly performance related), so changes are
expected.
What uses of trace_mark() depend on a stable interface? blktrace?
--
error compiling committee.c: too many arguments to function
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