From: Sasha Levin <levinsasha928@gmail.com>
To: Krishna Kumar2 <krkumar2@in.ibm.com>
Cc: Asias He <asias.hejun@gmail.com>,
gorcunov@gmail.com, kvm@vger.kernel.org, mingo@elte.hu,
"Michael S. Tsirkin" <mst@redhat.com>,
netdev@vger.kernel.org, penberg@kernel.org,
Rusty Russell <rusty@rustcorp.com.au>,
virtualization@lists.linux-foundation.org
Subject: Re: [RFC] kvm tools: Implement multiple VQ for virtio-net
Date: Tue, 15 Nov 2011 17:30:29 +0200 [thread overview]
Message-ID: <1321371029.3178.9.camel@lappy> (raw)
In-Reply-To: <OFDA747DDD.8D1C8FD8-ON65257949.001837DA-65257949.0019D25F@in.ibm.com>
On Tue, 2011-11-15 at 10:14 +0530, Krishna Kumar2 wrote:
> Sasha Levin <levinsasha928@gmail.com> wrote on 11/14/2011 03:45:40 PM:
>
> > > Why both the bandwidth and latency performance are dropping so
> > > dramatically with multiple VQ?
> >
> > It looks like theres no hash sync between host and guest, which makes
> > the RX VQ change for every packet. This is my guess.
>
> Yes, I confirmed this happens for macvtap. I am
> using ixgbe - it calls skb_record_rx_queue when
> a skb is allocated, but sets rxhash when a packet
> arrives. Macvtap is relying on record_rx_queue
> first ahead of rxhash (as part of my patch making
> macvtap multiqueue), hence different skbs result
> in macvtap selecting different vq's.
I'm seeing this behavior in non-macvtep related setup as well (simple
tap <-> virtio-net).
--
Sasha.
next prev parent reply other threads:[~2011-11-15 15:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-11 22:12 [RFC] kvm tools: Implement multiple VQ for virtio-net Sasha Levin
2011-11-13 10:24 ` Michael S. Tsirkin
2011-11-13 15:00 ` Sasha Levin
2011-11-13 15:32 ` Sasha Levin
2011-11-14 2:04 ` Asias He
2011-11-14 10:15 ` Sasha Levin
2011-11-15 4:44 ` Krishna Kumar2
2011-11-15 15:30 ` Sasha Levin [this message]
2011-11-15 15:30 ` Sasha Levin
2011-11-16 6:10 ` jason wang
2011-11-16 9:09 ` Krishna Kumar2
2011-11-16 10:05 ` jason wang
2011-11-14 10:15 ` Sasha Levin
2011-11-14 12:25 ` Pekka Enberg
2011-11-14 12:25 ` Pekka Enberg
2011-11-14 13:05 ` Michael S. Tsirkin
2011-11-16 0:04 ` Rusty Russell
2011-11-16 7:23 ` Michael S. Tsirkin
2011-11-21 0:41 ` Rusty Russell
2011-11-22 18:14 ` Stephen Hemminger
2011-11-22 18:14 ` Stephen Hemminger
2011-11-14 2:04 ` Asias He
2011-11-13 15:00 ` Sasha Levin
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