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From: Jan Kiszka <jan.kiszka@siemens.com>
To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org,
	Prerna Saxena <prerna@linux.vnet.ibm.com>,
	Anthony Liguori <aliguori@us.ibm.com>
Subject: Re: [PATCH 1/2] trace: Add simple tracing support
Date: Fri, 21 May 2010 13:13:49 +0200	[thread overview]
Message-ID: <4BF66AED.5080201@siemens.com> (raw)
In-Reply-To: <1274434947-2863-2-git-send-email-stefanha@linux.vnet.ibm.com>

Stefan Hajnoczi wrote:
> Trace events should be defined in trace.h.  Events are written to
> /tmp/trace.log and can be formatted using trace.py.  Remember to add
> events to trace.py for pretty-printing.

When already writing to a file, why not reusing QEMU's logging
infrastructure ("log <foo>" / "-d foo")? Shouldn't make a huge
performance difference if the data is saved in clear-text.

Also, having support for ftrace's user space markers would be a very
nice option (only an option as it's Linux-specific), see
http://lwn.net/Articles/366796. This allows to correlate kernel events
(KVM as well as others) with what goes on in QEMU. It simply enables
integration with the whole kernel tracing infrastructure, e.g.
KernelShark (http://people.redhat.com/srostedt/kernelshark/HTML).

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

WARNING: multiple messages have this Message-ID (diff)
From: Jan Kiszka <jan.kiszka@siemens.com>
To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org,
	Prerna Saxena <prerna@linux.vnet.ibm.com>
Subject: [Qemu-devel] Re: [PATCH 1/2] trace: Add simple tracing support
Date: Fri, 21 May 2010 13:13:49 +0200	[thread overview]
Message-ID: <4BF66AED.5080201@siemens.com> (raw)
In-Reply-To: <1274434947-2863-2-git-send-email-stefanha@linux.vnet.ibm.com>

Stefan Hajnoczi wrote:
> Trace events should be defined in trace.h.  Events are written to
> /tmp/trace.log and can be formatted using trace.py.  Remember to add
> events to trace.py for pretty-printing.

When already writing to a file, why not reusing QEMU's logging
infrastructure ("log <foo>" / "-d foo")? Shouldn't make a huge
performance difference if the data is saved in clear-text.

Also, having support for ftrace's user space markers would be a very
nice option (only an option as it's Linux-specific), see
http://lwn.net/Articles/366796. This allows to correlate kernel events
(KVM as well as others) with what goes on in QEMU. It simply enables
integration with the whole kernel tracing infrastructure, e.g.
KernelShark (http://people.redhat.com/srostedt/kernelshark/HTML).

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

  parent reply	other threads:[~2010-05-21 11:14 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-21  9:42 [RFC 0/2] Tracing Stefan Hajnoczi
2010-05-21  9:42 ` [Qemu-devel] " Stefan Hajnoczi
2010-05-21  9:42 ` [PATCH 1/2] trace: Add simple tracing support Stefan Hajnoczi
2010-05-21  9:42   ` [Qemu-devel] " Stefan Hajnoczi
2010-05-21  9:49   ` Stefan Hajnoczi
2010-05-21  9:49     ` [Qemu-devel] " Stefan Hajnoczi
2010-05-21 11:13   ` Jan Kiszka [this message]
2010-05-21 11:13     ` Jan Kiszka
2010-05-21 13:10     ` Stefan Hajnoczi
2010-05-21 13:10       ` [Qemu-devel] " Stefan Hajnoczi
2010-05-21 13:22       ` Jan Kiszka
2010-05-21 13:22         ` [Qemu-devel] " Jan Kiszka
2010-05-21 12:37   ` [Qemu-devel] " Anthony Liguori
2010-05-21 13:46     ` Jan Kiszka
2010-05-21 13:46       ` Jan Kiszka
2010-05-21 14:03       ` Anthony Liguori
2010-05-21 14:03         ` Anthony Liguori
2010-05-21 16:52         ` Jan Kiszka
2010-05-21 16:52           ` Jan Kiszka
2010-05-21 20:49           ` Stefan Hajnoczi
2010-05-21 20:49             ` Stefan Hajnoczi
2010-05-21 21:26             ` Christoph Hellwig
2010-05-21 21:26               ` Christoph Hellwig
2010-05-21 21:37             ` Jan Kiszka
2010-05-21 21:37               ` Jan Kiszka
2010-05-21 21:06           ` Anthony Liguori
2010-05-21 21:06             ` Anthony Liguori
2010-05-21 21:41             ` Jan Kiszka
2010-05-21 21:41               ` Jan Kiszka
2010-05-21 21:58               ` Anthony Liguori
2010-05-21 21:58                 ` Anthony Liguori
2010-05-21  9:42 ` [PATCH 2/2] trace: Trace write requests in virtio-blk, multiwrite, and paio_submit Stefan Hajnoczi
2010-05-21  9:42   ` [Qemu-devel] " Stefan Hajnoczi
2010-05-21 11:27 ` [Qemu-devel] [RFC 0/2] Tracing Prerna Saxena
2010-05-21 11:27   ` Prerna Saxena

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