Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753329Ab2KPTR5 (ORCPT ); Fri, 16 Nov 2012 14:17:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:17545 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753250Ab2KPTRz (ORCPT ); Fri, 16 Nov 2012 14:17:55 -0500 Date: Fri, 16 Nov 2012 16:56:27 -0200 From: Marcelo Tosatti To: Steven Rostedt Cc: Yoshihiro YUNOMAE , David Sharp , "H. Peter Anvin" , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Joerg Roedel , Hidehiro Kawai , Ingo Molnar , Avi Kivity , yrl.pp-manager.tt@hitachi.com, Masami Hiramatsu , Thomas Gleixner Subject: Re: Re: [RFC PATCH 0/2] kvm/vmx: Output TSC offset Message-ID: <20121116185627.GA28622@amt.cnet> References: <20121114013611.5338.15086.stgit@yunodevel> <1352858437.18025.47.camel@gandalf.local.home> <1352860305.18025.48.camel@gandalf.local.home> <50A355A2.5040101@hitachi.com> <1353078354.7586.14.camel@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1353078354.7586.14.camel@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2546 Lines: 62 On Fri, Nov 16, 2012 at 10:05:54AM -0500, Steven Rostedt wrote: > 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 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 You need the tsc offset change event and the main events to be ordered, so i can't see how this helps. -- 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/