From: Avi Kivity <avi@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <mhiramat@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <andi@firstfloor.org>,
Jim Keniston <jkenisto@us.ibm.com>,
kvm@vger.kernel.org,
systemtap-ml <systemtap@sources.redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -tip 0/6 V4] tracing: kprobe-based event tracer
Date: Fri, 03 Apr 2009 14:50:35 +0300 [thread overview]
Message-ID: <49D5F80B.7000305@redhat.com> (raw)
In-Reply-To: <20090403112639.GC31399@elte.hu>
Ingo Molnar wrote:
> ok, the structure and concept looks quite good now, really nice!
>
> I'm wondering about something i suggested many moons ago: to look
> into the KVM decoder+emulator (arch/x86/kvm/x86_emulate.c).
>
> I remember there were some issues with that (one problem being that
> the KVM decoder is a special-purpose thing covering specific range
> of execution environments - not a near-full integer-ops decoder like
> the one we are aiming for here) - are there any other fundamental
> problems beyond 'it has to be done' ?
>
> Conceptually we want just a single piece of decoder logic in
> arch/x86/. If the KVM folks are cool with it we could factor out the
> KVM one into arch/x86/lib/. But ... if there are compelling reasons
> to leave the KVM one alone in its limited environment we can do that
> too.
>
kvm has three requirements not needed by kprobes:
- it wants to execute instructions, not just decode them, including
generating faults where appropriate
- it is performance critical
- it needs to support 16-bit, 32-bit, and 64-bit instructions simultaneously
If an arch/x86/ decoder/emulator gives me these I'll gladly switch to
it. x86_emulate.c is high on my list of most disliked code.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2009-04-03 11:50 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-02 17:24 [PATCH -tip 0/6 V4] tracing: kprobe-based event tracer Masami Hiramatsu
2009-04-03 11:26 ` Ingo Molnar
2009-04-03 11:32 ` Andi Kleen
2009-04-03 11:50 ` Avi Kivity [this message]
2009-04-03 12:12 ` Ingo Molnar
2009-04-03 12:17 ` Avi Kivity
2009-04-03 12:26 ` Ingo Molnar
2009-04-03 12:33 ` Avi Kivity
2009-04-03 13:16 ` Vegard Nossum
2009-04-03 13:40 ` Avi Kivity
2009-04-03 13:52 ` Masami Hiramatsu
2009-04-05 19:37 ` Pekka Paalanen
2009-04-06 7:53 ` Avi Kivity
2009-04-03 12:25 ` Andi Kleen
2009-04-03 14:21 ` Masami Hiramatsu
2009-04-03 14:23 ` Ingo Molnar
2009-04-03 16:55 ` Masami Hiramatsu
2009-04-03 17:59 ` Jim Keniston
2009-04-03 14:30 ` Avi Kivity
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