Re: [RFC][PATCH 4/5] hugetlb: fix cpuset-constrained pool resizing

[Nishanth Aravamudan <nacc@us.ibm.com>]

On 06.08.2007 [11:41:12 -0700], Christoph Lameter wrote:
> On Mon, 6 Aug 2007, Nishanth Aravamudan wrote:
> 
> > I understand what you mean, that root should be able to do whatever it
> > wants, but at the same time, if a root-owned process is running in a
> > cpuset, it's constrained for a reason.
> 
> Yes but the constraint is for an application running under a regular 
> user id not for the root user.
> 
> > More importantly, let's say your process (owned by root or not) is
> > running in a restricted cpuset on  nodes 2 and 3 of a 4-node system and
> > wants to use 100 hugepages. Using the global sysctl, presuming an equal
> > distribution of free memory on all nodes, said process would need to
> > allocate 200 hugepages on the system (50 on each node), to get 100
> > hugepages on nodes 2 and 3. With this patch, it only needs to allocate
> > 100 hugepages.
> 
> The app is not able to use the sysctl. The root user must be able to do 
> whatever desired. Does not make sense to impose restrictions on sysctls.
> 
> > Become dependent on the *proccess* context, which is, to me, what would
> > be expected. If a process is restricted in some way, I would expect it
> > to be restricted in that way across the board.
> 
> Nope these values are global. Cpuset relative data belongs in /dev/cpuset.

Ok, I'll respin the patches with this in mind and resubmit.

Thanks for the feedback,
Nish

-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center

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