CRR: 7032531: G1: enhance GC logging to include more accurate eden / survivor size transitions (S/XS)

[Poonam Bajaj]

Hi Tony,

On 6/7/2011 11:40 PM, Tony Printezis wrote:
> Hi all,
>
> Could I have a couple of reviews for this change?
>
> http://cr.openjdk.java.net/~tonyp/7032531/webrev.0/
>
> This enhances the G1 +PrintGCDetails output to include how much space 
> there is in the eden and survivor regions before / after a GC. Here's 
> an example of the output:
>
>    [Eden: 18M->0B Survivors: 1024K->2048K Heap: 27M(105M)->12M(125M)]
>
> It shows that the eden had 18MB before the GC and it's empty after it 
> (as expected!), the survivors were 1MB before the GC and grew to 2MB 
> after the GC, the used space in the heap fell from 27MB to 12MB, and 
> finally the heap size grew from 105MB to 125MB.
>
The heap size ( grew from 105K to 125K) here means the total size of all 
the regions in G1 heap (including young regions) ?

Thanks,
Poonam

> Note that, currently, the eden / survivor sizes that are reported are 
> not very accurate. They are currently calculated as region_num * 
> region_size. It'd be better if they were calculated as the used byte 
> total in the eden and survivor regions. But this would require a fair 
> amount of extra changes to do (I'd rather avoid iterating over them to 
> calculate that). We'll do that change when we revamp the region lists 
> that keep track of the eden / survivor regions (which is currently 
> work-in-progress).
>
> Tony
>

-- 
Best regards, Poonam

Sun, an Oracle company
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Poonam Bajaj | Staff Engineer
Phone: +66937451 <tel:+66937451> | Mobile: +9844511366 <tel:+9844511366>
JVM Sustaining Engineering
| Bangalore
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