From mboxrd@z Thu Jan  1 00:00:00 1970
From: mulyadi.santosa@gmail.com (Mulyadi Santosa)
Date: Thu, 9 Feb 2012 00:04:21 +0700
Subject: blktrace vs ftrace
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Hi Matthias...

On Wed, Feb 8, 2012 at 17:59, Matthias Brugger
<matthias.bgg@googlemail.com> wrote:
> If I understand the patch which introduces the blk tracer to ftrace
> (http://lwn.net/Articles/315508/) just uses the blktrace interface. So I
> wonder why using this influences the I/O behaviour.

Then I am completely clueless now. Better consult with qemu-devel mailing list.

PS: just crossed my mind, maybe ftrace that uses blktrace is actually
tracing the qemu's virtio. Whereas blktrace is tracing the physical
block access. This is just speculation, after re-reading that you use
virtio and disable write caching.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com