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Re: [Xen-devel] bad write performance with qdisk with larger files in pv

To: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Subject: Re: [Xen-devel] bad write performance with qdisk with larger files in pv-domU
From: Ronny Hegewald <ronny.hegewald@xxxxxxxxx>
Date: Sat, 4 Jun 2011 01:49:45 +0000
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> You could also use this patch:
>, http://darnok.org/xen/qdisk_vs_blkback_v3.1/qemu-enable-aio.patch

Wasn't aware of that patch, i will try it out.

> But why not use the 3.0-rc1 with the xen-blkback? Or if you want to use
> 2.6.39 you could use the
> git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git
> stable/2.6.39.x tree

I planned to try out the qdisk/qemu blktap implementation a bit. The missing 
xen-blkback in officiall 2.6.39 was just a good opportunity for this.

And from what i have read the future of blktap might be more in qemu then in 
the kernel, so thats another reason to get used to it.

> > Is this performance-impact expected when no AIO is used?
> Yeah, it is slow.

Ok, then no reason to dig deeper into that. So my current impression is that 
its better not use qdisk/qemu-blktap until xen can use upstream qemu?

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