[Lxc-users] cgroup behavior

[David Parks]

Speaking of cgroup behavior, you reminded me, I have an open question that
nobody managed to pick up on unix.stackexchange.com regarding blkio not
working as expected, maybe you can take a stab at it...

 

I've got 2 LXC containers with these cgroup settings:

 

lxc.cgroup.blkio.weight = 200

lxc.cgroup.cpu.shares = 200

 

  and another container with:

lxc.cgroup.blkio.weight = 800

lxc.cgroup.cpu.shares = 800

 

I have verified in /sys/fs/cgroup/blkio/lxc/<container-name>/blkio.weight is
indeed set to 200 on the host OS.

 

I have verified that cpu.shares are indeed split up, 80% to container 1 and
20% to container 2.

 

But when I run this command in both containers:

 

# write a 10GB file to disk

dd bs=1M count=10000 if=/dev/zero of=1test conv=fdatasync

 

I ran a similar test on reads.:

 

davidparks21 at test-cgroups1:/tmp$ time sh -c "dd if=1test of=/dev/null bs=1M"

10000+0 records in

10000+0 records out

10485760000 bytes (10 GB) copied, 37.9176 s, 277 MB/s

 

real    0m37.939s

user    0m0.004s

sys     0m24.306s

 

The IO speeds see in iotop on the host OS are virtually the same between the
two containers.

 

I expected to see container 2 command 80% of the IO access in this case.

 

 

-----Original Message-----
From: Serge Hallyn [mailto:serge.hallyn at ubuntu.com] 
Sent: Saturday, April 13, 2013 12:22 AM
To: David Parks
Cc: lxc-users at lists.sourceforge.net
Subject: Re: [Lxc-users] Very odd lxc behavior

 

Quoting David Parks ( <mailto:davidparks21 at yahoo.com>
davidparks21 at yahoo.com):

> Vanilla 12.10 Ubuntu server:

> 

>  

> 

> root at atlas01:~# sudo lxc-version

> 

> lxc version: 0.8.0-rc1

> 

>  

> 

> I may very well have accidentally tried to start the same container 

> twice, I think I fat-fingered something just before encountering the 

> issue, and I've never had it happen on any of our other boxes. Anyway, 

> it's of no real consequence to me now as I cleared it easily enough, 

> but I thought it worth mentioning.

 

Thanks.  Yeah 0.8.0 didn't yet have the new cgroup behavior, I don't think.

 

-serge

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