AllocateHeapAt flag cannot take effect in ZGC

Per Liden per.liden at
Sun Sep 15 18:39:05 UTC 2019


On 9/15/19 5:51 PM, Haoyu Li wrote:
> Hi all,
> I'm using ZGC with the -XX:AllocateHeapAt=<*path*> flag, and the *path* is
> pointing to a mounted device. However, this flag seems not to work with ZGC
> because I find that JVM still allocates its heap at DRAM instead of the
> specified device. I'm wondering is there any workaround? Thanks!

The -XX:AllocateHeapAt flag is currently not supported with ZGC.

The -XX:ZPath flag has a very similar meaning for ZGC, but you can 
currently only point it to a tmpfs or hugetlbfs mount, not a DAX-enabled 
filesystems. There are no technical reasons why this can't be supported 
in ZGC, it just hasn't been implemented yet.


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