MaxTenuringThreshold has a new ergonomic value???
Thomas Schatzl
thomas.schatzl at oracle.com
Tue Sep 3 00:24:56 PDT 2013
Hi,
On Mon, 2013-09-02 at 11:58 +0200, Kirk Pepperdine wrote:
> Hi,
>
> Where does ergonomics calculate MaxTenuringhreshold for ParNew? It seems
>that I missed the memo that the default ergonomics setting for this
>flag has drifted from 4 to 6? Is this now the case?
arguments.cpp, Arguments::set_cms_and_parnew_gc_flags():
1218: intx tenuring_default = (intx)6;
[...]
1286: // Unless explicitly requested otherwise, definitely
1287: // promote all objects surviving "tenuring_default" scavenges.
1288: if (FLAG_IS_DEFAULT(MaxTenuringThreshold) &&
1289: FLAG_IS_DEFAULT(SurvivorRatio)) {
1290: FLAG_SET_ERGO(uintx, MaxTenuringThreshold, tenuring_default);
1291: }
Note that the most recent change in line 1218 of that file dates back to
March 2011.
I do not know the rationale for this change.
The RFR does not give additional details:
http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2011-March/002384.html
Hth,
Thomas
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