Re: [RFC][2/3] Account and control virtual address space allocations

[Balbir Singh <balbir@linux.vnet.ibm.com>]

Dave Hansen wrote:
> On Tue, 2008-03-18 at 06:44 +0530, Balbir Singh wrote: 
>>> If you're going to do this, I think you need a couple of phases.  
>>>
>>> 1. update the vm_(un)acct_memory() functions to take an mm
>> There are other problems
>>
>> 1. vm_(un)acct_memory is conditionally dependent on VM_ACCOUNT. Look at
>> shmem_(un)acct_size for example
> 
> Yeah, but if VM_ACCOUNT isn't set, do you really want the controller
> accounting for them?  It's there for a reason. :)
> 

We are trying to account for virtual memory usage. Please see
http://lwn.net/Articles/5016/ to see what VM_ACCOUNT does or
Documentation/vm/overcommit-accounting. We want to account and control virtual
memory usage and not necessarily implement overcommit accounting

> The shmem_acct_size() helpers look good.  I wonder if we should be using
> that kind of things more generically.
> 

Yes, it is well written. I wish there were more such abstractions, but it does
not help us.

>> 2. These routines are not called from all contexts that we care about (look at
>> insert_special_mapping())
> 
> Could you explain why "we" care about it and why it isn't accounted for
> now?

It is accounted for in total_vm and that's why we care about :)

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

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