From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Vlad Yasevich <vyasevich@gmail.com>, vyasevic@redhat.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: Mon, 03 Mar 2014 10:11:35 +0100 [thread overview]
Message-ID: <53144747.2070605@de.ibm.com> (raw)
In-Reply-To: <53123495.7030902@gmail.com>
On 01/03/14 20:27, Vlad Yasevich wrote:
> On 03/01/2014 06:15 AM, Christian Borntraeger wrote:
>> On 28/02/14 23:14, Vlad Yasevich wrote:
>>> 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.
>>
>> Dont know if the different bytes/packets ratio is really the reason or
>> just a side effect. As a hint: the underlying network device does not support
>> segmentation, but this should not matter for traffic between to guests.
>
> Could you post 'ethtool -k' output for both lower-level device and the
> macvtap device?
Features for eth0:
rx-checksumming: off [fixed]
tx-checksumming: off
tx-checksum-ipv4: off [fixed]
tx-checksum-ip-generic: off [fixed]
tx-checksum-ipv6: off [fixed]
tx-checksum-fcoe-crc: off [fixed]
tx-checksum-sctp: off [fixed]
scatter-gather: off
tx-scatter-gather: off [fixed]
tx-scatter-gather-fraglist: off [fixed]
tcp-segmentation-offload: off
tx-tcp-segmentation: off [fixed]
tx-tcp-ecn-segmentation: off [fixed]
tx-tcp6-segmentation: off [fixed]
udp-fragmentation-offload: off [fixed]
generic-segmentation-offload: off [requested on]
generic-receive-offload: on
large-receive-offload: off [fixed]
rx-vlan-offload: off [fixed]
tx-vlan-offload: off [fixed]
ntuple-filters: off [fixed]
receive-hashing: off [fixed]
highdma: off [fixed]
rx-vlan-filter: on [fixed]
vlan-challenged: off [fixed]
tx-lockless: off [fixed]
netns-local: off [fixed]
tx-gso-robust: off [fixed]
tx-fcoe-segmentation: off [fixed]
tx-gre-segmentation: off [fixed]
tx-ipip-segmentation: off [fixed]
tx-sit-segmentation: off [fixed]
tx-udp_tnl-segmentation: off [fixed]
tx-mpls-segmentation: off [fixed]
fcoe-mtu: off [fixed]
tx-nocache-copy: off
loopback: off [fixed]
rx-fcs: off [fixed]
rx-all: off [fixed]
tx-vlan-stag-hw-insert: off [fixed]
rx-vlan-stag-hw-parse: off [fixed]
rx-vlan-stag-filter: off [fixed]
l2-fwd-offload: off [fixed]
Features for macvtap1:
rx-checksumming: off [fixed]
tx-checksumming: off
tx-checksum-ipv4: off [fixed]
tx-checksum-ip-generic: off [fixed]
tx-checksum-ipv6: off [fixed]
tx-checksum-fcoe-crc: off [fixed]
tx-checksum-sctp: off [fixed]
scatter-gather: off
tx-scatter-gather: off [fixed]
tx-scatter-gather-fraglist: off [fixed]
tcp-segmentation-offload: off
tx-tcp-segmentation: off [fixed]
tx-tcp-ecn-segmentation: off [fixed]
tx-tcp6-segmentation: off [fixed]
udp-fragmentation-offload: off [fixed]
generic-segmentation-offload: off [requested on]
generic-receive-offload: on
large-receive-offload: off [fixed]
rx-vlan-offload: off [fixed]
tx-vlan-offload: off [fixed]
ntuple-filters: off [fixed]
receive-hashing: off [fixed]
highdma: off [fixed]
rx-vlan-filter: on [fixed]
vlan-challenged: off [fixed]
tx-lockless: on [fixed]
netns-local: off [fixed]
tx-gso-robust: off [fixed]
tx-fcoe-segmentation: off [fixed]
tx-gre-segmentation: off [fixed]
tx-ipip-segmentation: off [fixed]
tx-sit-segmentation: off [fixed]
tx-udp_tnl-segmentation: off [fixed]
tx-mpls-segmentation: off [fixed]
fcoe-mtu: off [fixed]
tx-nocache-copy: off
loopback: off [fixed]
rx-fcs: off [fixed]
rx-all: off [fixed]
tx-vlan-stag-hw-insert: off [fixed]
rx-vlan-stag-hw-parse: off [fixed]
rx-vlan-stag-filter: off [fixed]
l2-fwd-offload: off [fixed]
prev parent reply other threads:[~2014-03-03 9:11 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
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 [this message]
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