From: Vlad Yasevich <vyasevic@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Jason Wang <jasowang@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
netdev@vger.kernel.org, KVM list <kvm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: macvtap performance regression (bisected) between 3.13 and 3.14-rc1
Date: Fri, 28 Feb 2014 17:14:58 -0500 [thread overview]
Message-ID: <53110A62.7070109@redhat.com> (raw)
In-Reply-To: <530FA586.3010400@de.ibm.com>
On 02/27/2014 03:52 PM, Christian Borntraeger wrote:
> Vlad,
>
> commit 6acf54f1cf0a6747bac9fea26f34cfc5a9029523
> macvtap: Add support of packet capture on macvtap device.
>
> causes a performance regression for iperf traffic between two KVM guests
> on my s390 system. Both guests are connected via two macvtaps on the same OSA
> network card.
> Before that patch I get ~20 Gbit/sec between two guests, afterwards I get
> ~4Gbit/sec
>
> Latency seems to be unchanges (uperf 1byte ping pong).
>
> According to ifconfig in the guest, I have ~ 1500 bytes per packet with this
> patch and ~ 40000 bytes without. So for some reason this patch causes the
> network stack to do segmentation. (the guest kernel stays the same, only host
> kernel is changed).
>
> Any ideas?
I am looking. It shouldn't cause addition segmentations and when I ran
netperf on the code I didn't see any difference in the throughput.
-vlad
>
>
> Christian
>
next prev parent reply other threads:[~2014-02-28 22:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-27 20:52 macvtap performance regression (bisected) between 3.13 and 3.14-rc1 Christian Borntraeger
2014-02-28 22:14 ` Vlad Yasevich [this message]
2014-03-01 11:15 ` Christian Borntraeger
2014-03-01 19:27 ` Vlad Yasevich
2014-03-02 1:21 ` Vlad Yasevich
2014-03-03 9:13 ` Christian Borntraeger
2014-03-03 19:36 ` Vlad Yasevich
2014-03-03 9:11 ` Christian Borntraeger
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