RFR(S): 8209162: Page size selection does not always select optimal page size

[Thomas Schatzl]

Hi,

On 21.04.20 13:18, Stefan Johansson wrote:
> Hi Ivan,
> 
> I'm not very familiar with this code, but one observation. This is a bit 
> similar to what I looked at recently for G1. There the region size was 
> different for a given heap size depending on if Xms was set or not. Here 
> we can run into a situation where the page size differ depending on Xms, 
> and this also feels a bit strange. Would there be a problem to simplify 
> this to a single line and always just care about min:
> const size_t page_sz = os::page_size_for_region_aligned(MinHeapSize, 4);
> 
> I'm trying to understand when this would be a problem, but can't think 
> of anything straight away.
> 

   the RFE is a suggestion to maximize page sizes when Xms == Xmx. I.e. 
if you do that, you do not care about uncommitting memory, so there is 
no need for being able to uncommit. In this case it is favorable to use 
maximum page size for throughput.

Thanks,
   Thomas