State of G1's "throughput barriers"?
thomas.schatzl at oracle.com
Tue Nov 12 09:41:57 UTC 2019
On 09.11.19 15:54, Clemens Eisserer wrote:
> With great excitement I read about the proposal to add a
> throughput-mode to G1 - has there been any progress on this?
> In some cases the throughput overhead G1 introduced compared to CMS is
> quite noticeable, especially for the case where 2-5s pauses are quite
> tolerable - i really hoped to get an option to trade a bit of latency
> for better throughput.
> Thanks, Clemens
the throughput barrier effort (or actually: optimize G1 when
disabling refinement) afaict consists of two main steps:
- changing the existing barrier so that the throughput barrier is not
completely different, allowing some interesting further optimizations.
This is mostly JDK-8087198 (currently out for review), and JDK-8226731,
which improves the existing barrier already a bit.
- enabling the smaller barrier if concurrent refinement is disabled (via
a new -XX:-G1UseConcRefinement). This is JDK-8134303 and ultimately
Man Cao from Google is working on this, and it seems that we'll get at
least the first big part soon. :)
Maybe Man wants to chime in for further details.
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