RFR(M): 8171181: Supporting heap allocation on alternative memory devices

[Kharbas, Kishor]

Hi Andrew,

> -----Original Message-----
> From: hotspot-runtime-dev [mailto:hotspot-runtime-dev-
> bounces at openjdk.java.net] On Behalf Of Andrew Haley
> Sent: Tuesday, February 28, 2017 1:33 AM
> To: hotspot-runtime-dev at openjdk.java.net
> Subject: Re: RFR(M): 8171181: Supporting heap allocation on alternative
> memory devices
> 
> Is it -XX:HeapDir or -XX:AllocateHeapAt ?  JEP says AllocateHeapAt, impl does
> not.
> 
> +             "Limit on number of compiler directives.")                     \
> +                                                                            \
> +  product(ccstr, HeapDir, NULL,                                             \
> +          "Path to the directoy where a temporary file will be created      \
> +           to use as the backing store for Java Heap.")
> 
> 
> Spell "directory"
> 

My thinking was to wait until the flag name is finalized in the JEP. I myself am not completely happy with the name so I was thinking if the community comes up with a better one.


> Do we ever envisage splitting the heap over memory types?
> 

Yes there could be a java heap split over memory types and object can be allocated in respective memories using automatic (using profiling) placement or user directed by APIs and/or language extensions.

> Is it essential to disable NUMA when using alternative memory devices?
> 

>From the research I have done, the DAX filesystem do not support NUMA-aware placement.

> Andrew.