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Re: [patch00/05]: Containers(V2)- Introduction [message #6619 is a reply to message #6523]

Wed, 20 September 2006 19:48

Paul Jackson
Messages: 157
Registered: February 2006

Senior Member

Peter wrote:
> > Which comes naturally with cpusets.
>
> How are shared mappings dealt with, are pages charged to the set that
> first faults them in?

Cpusets does not attempt to manage how much memory a task can allocate,
but where it can allocate it. If a task can find an existing page to
share, and avoid the allocation, then it entirely avoids dealing with
cpusets in that case.

Cpusets pays no attention to how often a page is shared. It controls
which tasks can allocate a given free page, based on the node on which
that page resides. If that node is allowed in a tasks 'nodemask_t
mems_allowed' (a task struct field), then the task can allocate
that page, so far as cpusets is concerned.

Cpusets does not care who links to a page, once it is allocated.

Every page is assigned to one specific node, and may only be allocated
by tasks allowed to allocate from that node.

These cpusets can overlap - which so far as memory goes, roughly means
that the various mems_allowed nodemask_t's of different tasks can overlap.

Here's an oddball example configuration that might make this easier to
think about.

Let's say we have a modest sized NUMA system with an extra bank
of memory added, in addition to the per-node memory. Let's say
the extra bank is a huge pile of cheaper (slower) memory, off a
slower bus.

Normal sized tasks running on one or more of the NUMA nodes just
get to fight for the CPUs and memory on those nodes allowed them.

Let's say an occassional big memory job is to be allowed to use
some of the extra cheap memory, and we use the idea of Andrew
and others to split that memory into fake nodes to manage the
portion of memory available to specified tasks.

Then one of these big jobs could be in a cpuset that let it use
one or more of the CPUs and memory on the node it ran on, plus
some number of the fake nodes on the extra cheap memory.

Other jobs could be allowed, using cpusets, to use any combination
of the same or overlapping CPUs or nodes, and/or other disjoint
CPUs or nodes, fake or real.

Another example, restating some of the above.

If say some application happened to fault in a libc.so page,
it would be required to place that page on one of the nodes
allowed to it. If an other application comes along later and
ends up wanting shared references to that same page, it could
certainly do so, regardless of its cpuset settings. It would
not be allocating a new page for this, so would not encounter
the cpuset constraints on where it could allocate such a page.

--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@sgi.com> 1.925.600.0401

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[Message index]

		[patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 02:16
		Re: [patch00/05]: Containers(V2)- Introduction By: Nick Piggin on Wed, 20 September 2006 05:39
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 16:27
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 16:26
		Re: [patch00/05]: Containers(V2)- Introduction By: Cedric Le Goater on Wed, 20 September 2006 13:06
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 16:45
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 16:48
		Re: [patch00/05]: Containers(V2)- Introduction By: Nick Piggin on Wed, 20 September 2006 17:07
		Re: [patch00/05]: Containers(V2)- Introduction By: Nick Piggin on Wed, 20 September 2006 16:56
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 17:08
		Re: [patch00/05]: Containers(V2)- Introduction By: Nick Piggin on Wed, 20 September 2006 17:19
		Re: [patch00/05]: Containers(V2)- Introduction By: Alan Cox on Wed, 20 September 2006 17:16
		Re: [patch00/05]: Containers(V2)- Introduction By: Nick Piggin on Wed, 20 September 2006 17:00
		Re: [patch00/05]: Containers(V2)- Introduction By: Alan Cox on Wed, 20 September 2006 17:12
		Re: [patch00/05]: Containers(V2)- Introduction By: Nick Piggin on Wed, 20 September 2006 17:30
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 17:50
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 17:52
		Re: [patch00/05]: Containers(V2)- Introduction By: Peter Zijlstra on Wed, 20 September 2006 18:06
		Re: [patch00/05]: Containers(V2)- Introduction By: Peter Zijlstra on Wed, 20 September 2006 18:37
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Wed, 20 September 2006 17:23
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 16:25
		Re: [patch00/05]: Containers(V2)- Introduction By: Alan Cox on Wed, 20 September 2006 17:10
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 17:15
		Re: [patch00/05]: Containers(V2)- Introduction By: Alan Cox on Wed, 20 September 2006 17:24
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 17:35
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Wed, 20 September 2006 23:29
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Wed, 20 September 2006 23:18
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Wed, 20 September 2006 17:30
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 17:26
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 17:38
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 18:07
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 19:51
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Wed, 20 September 2006 20:06
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Wed, 20 September 2006 22:58
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 23:02
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 23:33
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 23:36
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 23:39
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 23:51
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Thu, 21 September 2006 00:05
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Thu, 21 September 2006 00:09
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 23:26
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 23:31
		Re: [Lhms-devel] [patch00/05]: Containers(V2)- Introduction By: KAMEZAWA Hiroyuki on Thu, 21 September 2006 00:47
		Re: [Lhms-devel] [patch00/05]: Containers(V2)- Introduction By: KAMEZAWA Hiroyuki on Thu, 21 September 2006 01:29
		Re: [ckrm-tech] [Lhms-devel] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Thu, 21 September 2006 01:36
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Wed, 20 September 2006 17:42
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Wed, 20 September 2006 22:51
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 23:01
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 23:22
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Wed, 20 September 2006 23:45
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Wed, 20 September 2006 17:37
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Chandra Seetharaman on Wed, 20 September 2006 18:34
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 19:52
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Chandra Seetharaman on Thu, 21 September 2006 00:31
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Thu, 21 September 2006 00:36
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Thu, 21 September 2006 00:42
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Wed, 20 September 2006 18:43
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Chandra Seetharaman on Wed, 20 September 2006 19:09
		Re: [patch00/05]: Containers(V2)- Introduction By: Nick Piggin on Wed, 20 September 2006 16:44
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 17:12
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Wed, 20 September 2006 22:27
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 22:59
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 17:30
		Re: [patch00/05]: Containers(V2)- Introduction By: Nick Piggin on Wed, 20 September 2006 18:03
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 18:14
		Re: [patch00/05]: Containers(V2)- Introduction By: Peter Zijlstra on Wed, 20 September 2006 18:27
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 18:38
		Re: [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 20 September 2006 18:57
		Re: [patch00/05]: Containers(V2)- Introduction By: Paul Jackson on Wed, 20 September 2006 19:48
		Re: [patch00/05]: Containers(V2)- Introduction By: Christoph Lameter on Wed, 20 September 2006 19:48
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Paul Menage on Wed, 20 September 2006 19:51
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Chandra Seetharaman on Wed, 27 September 2006 19:50
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Wed, 27 September 2006 21:28
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Chandra Seetharaman on Wed, 27 September 2006 22:24
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Balbir Singh on Thu, 28 September 2006 08:01
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Thu, 28 September 2006 18:31
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Balbir Singh on Thu, 28 September 2006 21:53
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Fri, 29 September 2006 00:22
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Thu, 28 September 2006 18:12
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Chandra Seetharaman on Thu, 28 September 2006 20:23
		Re: [ckrm-tech] [patch00/05]: Containers(V2)- Introduction By: Rohit Seth on Thu, 28 September 2006 21:38

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