RFR(M/L): 7145569: G1: optimize nmethods scanning

[John Cuthbertson]

Hi Thomas,

On 6/19/2013 1:33 PM, Thomas Schatzl wrote:
> Hi,
>
>    one issue I forgot to mention: currently when printing remembered set
> sizes, the new nmethod remembered set is not taken into account.
>
> I am asking myselves, isn't the _strong_code_root_list not a type of
> remembered set, and shouldn't it be added to this size? What do you
> think?

I think you're right. In fact I've been calling it a sort of remembered set.

>
> Additionally it would be really nice to make this information available
> in some form so that further (size related) issues in that area could be
> diagnosed.

In the short term we could certainly add a strong_code_root_mem_size() 
routine to HeapRegion and call that from the appropriate places. It 
should be straight forward - GroableArrays keep track of their capacity.

>
> Unfortunately at the moment the _strong_roots_code_list is located in
> HeapRegion, not in the remembered set, where the method to get its size
> is.

Again calling a routine from the HeapRegion that "own" the RSet should 
be OK.  I'll send out a new webrev when I've done this.

Longer term moving the code roots in to the actual Rset structure (not 
OtherRegionsTable though) is desirable. I'll investigate how much effort 
it will be to this.

Thanks,

JohnC