RFR (XXS): 8143220: Fix documentation of InitiatingHeapOccupancyPercent

ecki at zusammenkunft.net ecki at zusammenkunft.net
Fri Feb 5 14:49:34 UTC 2016


Isnt this used for CMS also? Should it mention OccupancyOnly option? What is meant with "at the end of next GC"?


-----Original Message-----
From: "kirk at kodewerk.com" <kirk at kodewerk.com>
To: Thomas Schatzl <thomas.schatzl at oracle.com>
Cc: hotspot-gc-dev at openjdk.java.net
Sent: Fr., 05 Feb. 2016 15:05
Subject: Re: RFR (XXS): 8143220: Fix documentation of InitiatingHeapOccupancyPercent


Does this represent a change in behavior aside from it being adaptive. I ask because I understand this comment to suggest that IHOP is no longer based on total heap occupancy but instead just on tenured occupancy.
Sorry but aside from that I find the comment some what confusing. Can you confirm that what I’ve written is what is meant.

"The percent occupancy (IHOP) of old generational heap after which a concurrent mark cycle with be initiated with the next GC. The value maybe changed if adaptive IHOP is enabled. Otherwise the value remains constant. Setting a value of 0 will result in frequent concurrent marking cycles. (G1 collector only)”

+          "Percentage of the old gen heap occupancy to start a concurrent " \
+          "GC cycle (IHOP) at the end of the next GC. "                     \
+          "If the IHOP value is determined adaptively by the collector, "   \
+          "this value is used as the initial value while there is not "     \
+          "enough information to do the adaptive sizing. Otherwise this "   \
+          "value is fixed. In this case, setting a value of 0 causes "      \
+          "concurrent marking to run as much as possible. "                 \
+          "Used in the G1 collector only.")

Kind regards,

> On Feb 5, 2016, at 11:52 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> Hi all,
>  can I have reviews for this change to the documentation of the
> InitiatingHeapOccupancyPercent global? I think due to recent changes
> to the behavior it is warranted that the (internal) documentation
> reflects it.
> Other suggestions for the text welcome.
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8143220
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8143220/webrev/
> Testing:
> local compilation
> Thanks,
>  Thomas

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