Vif rate limiting

Vif rate limiting

[Padala, Pradeep]

Hi,

I am trying to find information of vif rate limiting in the unstable
trunk. I see that the netif.py takes the 'rate' option while setting up
vifs, but that option seems to have no affect. Does it work ? If yes, is
there any documentation on how to access it?

Thanks,
Pradeep

Re: Vif rate limiting

[Keir Fraser]

It should work. Are you passing a valid rate string when creating the VIF?

 -- Keir


On 5/3/07 15:19, "Padala, Pradeep" <pradeep.padala@hp.com> wrote:

> Hi,
> 
> I am trying to find information of vif rate limiting in the unstable
> trunk. I see that the netif.py takes the 'rate' option while setting up
> vifs, but that option seems to have no affect. Does it work ? If yes, is
> there any documentation on how to access it?
> 
> Thanks,
> Pradeep
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

RE: Vif rate limiting

[Padala, Pradeep]

> It should work. Are you passing a valid rate string when 
> creating the VIF?

This is the config line I am using.

vif = ['ip=15.25.117.44', 'rate=10MB/s']

Do I need to specify the interval_usecs variable too ?

Pradeep

> On 5/3/07 15:19, "Padala, Pradeep" <pradeep.padala@hp.com> wrote:
> 
> > Hi,
> > 
> > I am trying to find information of vif rate limiting in the 
> unstable 
> > trunk. I see that the netif.py takes the 'rate' option 
> while setting 
> > up vifs, but that option seems to have no affect. Does it work ? If 
> > yes, is there any documentation on how to access it?
> > 
> > Thanks,
> > Pradeep
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> 
> 

Re: Vif rate limiting

[Keir Fraser]

On 5/3/07 16:00, "Padala, Pradeep" <pradeep.padala@hp.com> wrote:

> This is the config line I am using.
> 
> vif = ['ip=15.25.117.44', 'rate=10MB/s']

This will rate-limit to 10 megabytes per second, not 10 megabits per second.
Is this what you meant? Otherwise you should use 'rate=10Mb/s'.

> Do I need to specify the interval_usecs variable too ?

No, a sane default value is chosen.

 -- Keir

RE: Vif rate limiting

[Padala, Pradeep]

> > This is the config line I am using.
> > 
> > vif = ['ip=15.25.117.44', 'rate=10MB/s']
> 
> This will rate-limit to 10 megabytes per second, not 10 
> megabits per second.
> Is this what you meant? Otherwise you should use 'rate=10Mb/s'.

Yes, I meant 10Mbytes/sec, since we have 1gbit interfaces. I have an
apache server serving a 1G file, and I download the file from another
machine, that is on the same enclosure. So, the network is very fast.

I see an output like below. I posted a message earlier
(http://lists.xensource.com/archives/html/xen-devel/2007-03/msg00026.htm
l) describing similar problems with tc as well. I have tried this setup
in a separate set of machines connected with 1gbit interfaces with same
results. Any help is greatly apperciated.

[root@acts-03 ~]# wget --no-proxy http://15.25.117.44/data1G.dat
--08:23:43--  http://15.25.117.44/data1G.dat
           => `data1G.dat'
Connecting to 15.25.117.44:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1,073,741,824 (1.0G) [text/plain]

100%[===========================>] 1,073,741,824  112.12M/s    ETA 00:00

08:23:53 (107.39 MB/s) - `data1G.dat' saved [1073741824/1073741824] 

The full configuration of the VM is below. I am using routed networking.

kernel = '/boot/vmlinuz-2.6-xen'
vif = ['ip=15.25.117.44', 'rate=10MB/s']
ip = '15.25.117.44'
name = 'hperf1'
#extra = 'ramdisk_size=524288'
hostname = 'hperf1'
netmask = '255.255.255.0'
user = 'padalap'
memory=1000
disk = ['file:/root/xen/vm1_8g.img,sda1,w',
'file:/root/xen/vm1.swp,sda2,w']
root = '/dev/sda1 ro'
gateway = '15.25.117.42'
restart = 'never'

Pradeep

Re: Vif rate limiting

[Keir Fraser]

With your domU running, if you 'xenstore-ls /local/domain/0 | grep rate' do
you see any output (i.e., has xend actually written a rate parameter into
xenstore for the netback driver to pick up)?

 -- Keir

On 5/3/07 16:34, "Padala, Pradeep" <pradeep.padala@hp.com> wrote:

>> 
>> This will rate-limit to 10 megabytes per second, not 10
>> megabits per second.
>> Is this what you meant? Otherwise you should use 'rate=10Mb/s'.
> 
> Yes, I meant 10Mbytes/sec, since we have 1gbit interfaces. I have an
> apache server serving a 1G file, and I download the file from another
> machine, that is on the same enclosure. So, the network is very fast.
> 
> I see an output like below. I posted a message earlier
> (http://lists.xensource.com/archives/html/xen-devel/2007-03/msg00026.htm
> l) describing similar problems with tc as well. I have tried this setup
> in a separate set of machines connected with 1gbit interfaces with same
> results. Any help is greatly apperciated.

RE: Vif rate limiting

[Padala, Pradeep]

> > This is what I get
> > 
> > [root@acts-02 xen]# xenstore-ls /local/domain/0 | grep rate
> >     rate = "500000,50000"
> > 
> > I am not sure what those numbers mean.
> 
> It means 500000 bytes may be sent every 50000 microseconds. 
> This corresponds to 10MB/s. 
> 
> Actually I think I see the problem: our traffic limiting is 
> only on the transmit side, not on the receive side. We don't 
> do receive-side limiting at all (at least, not right now).

You mean, receive from the perspective of dom0 ? AFAIK, there's no point
in rate-limiting the data that is bound to a VM, as the data already
traversed the network using up the bandwidth, and it's just a matter of
processing it.

Do you know why tc is not working as expected ? I also tried to setup tc
rules for the vifs, but tc doesn't seem to recognize the interfaces.

What's the best way to setup traffic shaping on a Xen system ?

Pradeep