Re: [ckrm-tech] [RFC][PATCH 5/7] UBC: kernel memory accounting (core)

[Kirill Korotaev <dev@sw.ru>]

Rohit Seth wrote:
> On Thu, 2006-08-17 at 17:35 +0400, Kirill Korotaev wrote:
>
>
> > > My preference would be to have container (I keep on saying container,
> > > but resource beancounter) pointer embeded in task, mm(not sure),
> > > address_space and anon_vma structures.  This should allow us to track
> > > user land pages optimally.  But for tracking kernel usage on behalf of
> > > user, we will have to use an additional field (unless we can re-use
> > > mapping).  Please correct me if I'm wrong, though all the kernel
> > > resources will be allocated/freed in context of a user process.  And at
> > > that time we know if a allocation should succeed or not.  So we may
> > > actually not need to track kernel pages that closely.  We are not going
> > > to run reclaim on any of them anyways.  
> >
> > objects are really allocated in process context
> > (except for TCP/IP and other softirqs which are done in arbitrary
> > process context!)
>
>
> Can these pages be tagged using mapping field of the page struct.
kernel pages can be taged with mapping field.
User pages - not. So we introduce 2 pointers in the unoin:
union {
 page_ub		// for kernel pages
 page_pb		// for user pages
}

> > And objects are not always freed in correct context (!).
>
> You mean beyond Networking and softirq.
>
>
> > Note, page_ub is not for _user_ pages. user pages accounting will be added
> > in next patch set. page_ub is added to track kernel allocations.
>
>
> But will the page_ub be used for some purpose for user land pages?
yes. see above.

Kirill

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