From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: vhost-net patches
Date: Tue, 27 Oct 2009 22:58:16 +0200
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Cc: Sridhar Samudrala <sri@us.ibm.com>, Shirley Ma <xma@us.ibm.com>,
	David Stevens <dlstevens@us.ibm.com>, kvm@vger.kernel.org,
	sri@linux.vnet.ibm.com, mashirle@linux.vnet.ibm.com
To: Shirley Ma <mashirle@us.ibm.com>
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On Tue, Oct 27, 2009 at 09:36:18AM -0700, Shirley Ma wrote:
> Hello Michael,
> 
> On Tue, 2009-10-27 at 17:27 +0200, Michael S. Tsirkin wrote:
> > Possibly GFP_ATOMIC allocations in vring_add_indirect are failing?
> > Is there a chance you are tight on guest memory for some reason?
> > with vhost, virtio does currently consume a bit more memory than
> > with userspace backend.
> 
> I did see memory leak on host every time after exiting guest. I don't
> know where. Do you see it?

I didn't notice. I'll check this.

> Anyway after I reboot host and restart guest with large memory
> allocation,

How large is large here? I usually allocate 1G.

> I do see performance improves to 3xxxMb/s, and occasionally
> reaches 40xxMb/s.

This is same as userspace, isn't it?

> But "queue full" still exists, I can avoid the problem
> by increasing send queue size from qemu.

And what performance do you get then?

> I will apply deferring skb allocation patch on guest to see any
> performance gain after your vhost patch.
> 
> Thanks
> Shirley