From: Steven Rostedt <rostedt@goodmis.org>
To: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Cc: David Sharp <dhsharp@google.com>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Joerg Roedel <joerg.roedel@amd.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>,
Ingo Molnar <mingo@redhat.com>, Avi Kivity <avi@redhat.com>,
yrl.pp-manager.tt@hitachi.com,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Re: [RFC PATCH 0/2] kvm/vmx: Output TSC offset
Date: Fri, 16 Nov 2012 10:05:54 -0500 [thread overview]
Message-ID: <1353078354.7586.14.camel@gandalf.local.home> (raw)
In-Reply-To: <50A355A2.5040101@hitachi.com>
On Wed, 2012-11-14 at 17:26 +0900, Yoshihiro YUNOMAE wrote:
> Thank you for commenting on my patch set.
>
> (2012/11/14 11:31), Steven Rostedt wrote:
> > On Tue, 2012-11-13 at 18:03 -0800, David Sharp wrote:
> >> On Tue, Nov 13, 2012 at 6:00 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
> >>> On Wed, 2012-11-14 at 10:36 +0900, Yoshihiro YUNOMAE wrote:
> >>>
> >>>> To merge the data like previous pattern, we apply this patch set. Then, we can
> >>>> get TSC offset of the guest as follows:
> >>>>
> >>>> $ dmesg | grep kvm
> >>>> [ 57.717180] kvm: (2687) write TSC offset 18446743360465545001, now clock ##
> >>>> ^^^^ ^^^^^^^^^^^^^^^^^^^^ |
> >>>> PID TSC offset |
> >>>> HOST TSC value --+
> >>>>
> >>>
> >>> Using printk to export something like this is IMO a nasty hack.
> >>>
> >>> Can't we create a /sys or /proc file to export the same thing?
> >>
> >> Since the value changes over the course of the trace, and seems to be
> >> part of the context of the trace, I think I'd include it as a
> >> tracepoint.
> >>
> >
> > I'm fine with that too.
>
> Using some tracepoint is a nice idea, but there is one problem. Here,
> our discussion point is "the event which TSC offset is changed does not
> frequently occur, but the buffer must keep the event data."
If you can hold off a bit, for the 3.9 window, I plan on pushing
multiple buffers for ftrace. That is, you can create a separate buffer
just for the TSC offset events:
cd /sys/kernel/debug
echo tsc > instances/new
echo 1 > instances/tsc/events/tsc/offset/enable
Then the buffer will be used only for that event.
The code is pretty much ready, but I want to test it more before the 3.8
window opens, which is why I'm waiting for 3.9.
You can see the latest version here:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
branch: rfc/multi-buffers-v7
-- Steve
next prev parent reply other threads:[~2012-11-16 15:05 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-14 1:36 [RFC PATCH 0/2] kvm/vmx: Output TSC offset Yoshihiro YUNOMAE
2012-11-14 1:36 ` [RFC PATCH 1/2] kvm/vmx: Print TSC_OFFSET information when TSC offset value is written to VMCS Yoshihiro YUNOMAE
2012-11-14 1:37 ` [RFC PATCH 2/2] tools: Add a tool for merging trace data of a guest and a host Yoshihiro YUNOMAE
2012-11-14 2:00 ` [RFC PATCH 0/2] kvm/vmx: Output TSC offset Steven Rostedt
2012-11-14 2:02 ` H. Peter Anvin
2012-11-14 2:03 ` David Sharp
2012-11-14 2:31 ` Steven Rostedt
2012-11-14 8:26 ` Yoshihiro YUNOMAE
2012-11-16 15:05 ` Steven Rostedt [this message]
2012-11-16 18:56 ` Marcelo Tosatti
2012-11-20 10:38 ` Yoshihiro YUNOMAE
2012-11-16 19:15 ` Marcelo Tosatti
2012-11-20 10:36 ` Yoshihiro YUNOMAE
2012-11-20 22:51 ` Marcelo Tosatti
2012-11-22 5:21 ` Yoshihiro YUNOMAE
2012-11-23 22:46 ` Marcelo Tosatti
2012-11-26 11:05 ` Yoshihiro YUNOMAE
2012-11-26 23:16 ` Marcelo Tosatti
2012-11-27 10:53 ` Yoshihiro YUNOMAE
2012-11-29 22:51 ` Marcelo Tosatti
2012-11-30 1:36 ` Yoshihiro YUNOMAE
2012-11-30 20:42 ` Marcelo Tosatti
2012-12-03 0:55 ` Yoshihiro YUNOMAE
2012-11-16 3:19 ` Marcelo Tosatti
2012-11-16 8:09 ` Yoshihiro YUNOMAE
2012-11-16 10:05 ` Marcelo Tosatti
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