Subject: Re: [ckrm-tech] [RFC] Resource Management - Infrastructure choices
From: Matt Helsley <matthltc@us.ibm.com>
To: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>, vatsa@in.ibm.com, dev@openvz.org,
       sekharan@us.ibm.com, ckrm-tech@lists.sourceforge.net, balbir@in.ibm.com,
       haveblue@us.ibm.com, linux-kernel@vger.kernel.org, pj@sgi.com,
       dipankar@in.ibm.com, rohitseth@google.com
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Organization: IBM Linux Technology Center
Date: Thu, 02 Nov 2006 03:26:47 -0800
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On Thu, 2006-11-02 at 12:08 +0300, Pavel Emelianov wrote:
> [snip]
> 
> > I think that having a "tasks" file and a "threads" file in each
> > container directory would be a clean way to handle it:
> > 
> > "tasks" : read/write complete process members
> > "threads" : read/write individual thread members
> 
> I've just thought of it.
> 
> Beancounter may have more than 409 tasks, while configfs
> doesn't allow attributes to store more than PAGE_SIZE bytes
> on read. So how would you fill so many tasks in one page?

	To be clear that's a limitation of configfs as an interface. In the
Resource Groups code, for example, there is no hard limitation on length
of the underlying list. This is why we're talking about a filesystem
interface and not necessarily a configfs interface.

> I like the idea of writing pids/tids to these files, but
> printing them back is not that easy.

	That depends on how you do it. For instance, if you don't have an
explicit list of tasks in the group (rough cost: 1 list head per task)
then yes, it could be difficult.

Cheers,
	-Matt Helsley

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