Re: [PATCH 00/10] mm: Linux VM Infrastructure to support MemoryPower Management

[Ankita Garg]

Hi,

On Wed, Jun 29, 2011 at 01:11:00PM -0700, Andi Kleen wrote:
> Dave Hansen <dave@xxxxxxxxxxxxxxxxxx> writes:
> >
> > It's also going to be a pain to track kernel references.  On x86, our
> 

As Vaidy mentioned, we are only looking at memory being either allocated
or free, as a way to evacuate it. Tracking memory references, no doubt,
is a difficult proposition and might involve a lot of overhead.
 
> Even if you tracked them what would you do with them?
>
> It's quite hard to stop using arbitary kernel memory (see all the dancing
> memory-failure does) 
> 
> You need to track the direct accesses to user data which happens
> to be accessed through the direct mapping.
> 
> Also it will be always unreliable because this all won't track DMA.
> For that you would also need to track in the dma_* infrastructure,
> which will likely get seriously expensive.
> 

-- 
Regards,
Ankita Garg (ankita@xxxxxxxxxx)
Linux Technology Center
IBM India Systems & Technology Labs,
Bangalore, India
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