[Devel] Re: [PATCH -mmotm 0/5] memcg: per cgroup dirty limit (v7)

[Vivek Goyal]

On Thu, Mar 18, 2010 at 12:47:43AM +0530, Balbir Singh wrote:
> * Vivek Goyal <vgoyal at redhat.com> [2010-03-17 09:34:07]:
> 
> > On Wed, Mar 17, 2010 at 05:24:28PM +0530, Balbir Singh wrote:
> > > * Vivek Goyal <vgoyal at redhat.com> [2010-03-15 13:19:21]:
> > > 
> > > > On Mon, Mar 15, 2010 at 01:12:09PM -0400, Vivek Goyal wrote:
> > > > > On Mon, Mar 15, 2010 at 12:26:37AM +0100, Andrea Righi wrote:
> > > > > > Control the maximum amount of dirty pages a cgroup can have at any given time.
> > > > > > 
> > > > > > Per cgroup dirty limit is like fixing the max amount of dirty (hard to reclaim)
> > > > > > page cache used by any cgroup. So, in case of multiple cgroup writers, they
> > > > > > will not be able to consume more than their designated share of dirty pages and
> > > > > > will be forced to perform write-out if they cross that limit.
> > > > > > 
> > > > > 
> > > > > For me even with this version I see that group with 100M limit is getting
> > > > > much more BW.
> > > > > 
> > > > > root cgroup
> > > > > ==========
> > > > > #time dd if=/dev/zero of=/root/zerofile bs=4K count=1M
> > > > > 4294967296 bytes (4.3 GB) copied, 55.7979 s, 77.0 MB/s
> > > > > 
> > > > > real	0m56.209s
> > > > > 
> > > > > test1 cgroup with memory limit of 100M
> > > > > ======================================
> > > > > # time dd if=/dev/zero of=/root/zerofile1 bs=4K count=1M
> > > > > 4294967296 bytes (4.3 GB) copied, 20.9252 s, 205 MB/s
> > > > > 
> > > > > real	0m21.096s
> > > > > 
> > > > > Note, these two jobs are not running in parallel. These are running one
> > > > > after the other.
> > > > > 
> > > > 
> 
> The data is not always repeatable at my end. Are you able to modify
> the order and get repeatable results?
> 
> In fact, I saw
> 
> for cgroup != root
> ------------------
> 4294967296 bytes (4.3 GB) copied, 120.359 s, 35.7 MB/s
> 
> for cgroup = root
> -----------------
> 4294967296 bytes (4.3 GB) copied, 84.504 s, 50.8 MB/s
> 
> This is without the patches applied.

I lost the access to the big configuration machine but on that machine I
could reproduce it all the time. But on smaller machine (4core, 4G), I 
could not.

I will do some more tests later.

Vivek
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