RFR(S): 8025942: Implement os::Bsd:available_memory

[harold seigel]

Hi Gerard,

Since host_statistics64 is unlikely to fail, can you add an assert to 
ensure that we catch the rare case when it fails?

Thanks, Harold

On 10/11/2013 11:26 AM, Gerard Ziemski wrote:
> hi David,
>
> On 10/10/2013 11:32 PM, David Holmes wrote:
>> Hi Gerard,
>>
>> On 11/10/2013 5:14 AM, Gerard Ziemski wrote:
>>> Please review this fix that implements os::Bsd:available_memory()
>>>
>>> Description:
>>>
>>> This is a simple change - we use a similar implementation that Apple
>>> itself uses (see
>>> http://opensource.apple.com/source/system_cmds/system_cmds-498.2/vm_stat.tproj/vm_stat.c) 
>>>
>>> to implement BSD (Apple platform only) implementation for finding out
>>> available (free) memory.
>>
>> Is host_statistics64 likely to fail? If not then I think we should 
>> trap any failures, at least with an assert, so that they are noticed. 
>> Otherwise this might fail all the time and we would be none the wiser.
>
> I looked at the implementation of host_statistics64 in XNU src and the 
> only reason it will fail is if we pass wrong parameters (such as NULL 
> host). Otherwise, it is guaranteed to return a valid value, so there 
> does not seem to be a need for an assert here.
>
>
> cheers