Hi Yasumasa, Good question. I’ve never considered CMS to be a Full GC. This implies that there should be separate performance counters for CMS pause phases as it is possible to have FGC. Of course a FGC during CMS maybe user triggered, triggered outside a CMS cycle, interrupts a CMS cycle, or interrupts a CMS phase. I’m not sure how much of a distinction one needs to make here as that could be a quick broader discussion. Certainly the purpose isn’t to recreate the GC logs in these performance counters. But at the very least not having a distinction between full and a STW-CMS phase is kind of misleading in my opinion.
Regards, Kirk > On Mar 1, 2016, at 5:03 PM, Yasumasa Suenaga <yasue...@gmail.com> wrote: > > Hi Kirk, > >> It is also incorrect to count initial mark and remark in CMS as a FGC. > > Though, how can we check execution of major collection without GC log? > Should we add new PerfCounter for CGC (and add CGC column to jstat output)? > > > Yasumasa > > > On 2016/03/02 6:35, k...@kodewerk.com wrote: >> Hi, >> >> I think it is incorrect to count remark and cleanup as FGC. They are not >> full collections. It is also incorrect to count initial mark and remark in >> CMS as a FGC. It is unfortunate that this is counted this way. >> >> Regards, >> Kirk >> >>> On Mar 1, 2016, at 8:56 AM, Yasumasa Suenaga <yasue...@gmail.com> wrote: >>> >>> Hi all, >>> >>> I wonder that STW phases (Remark and Cleanup) at G1 are not counted in >>> jstat FGC column. >>> For example, Initial Mark and Remark at CMS are counted as FGC. >>> >>> For consistency, I think that G1 STW phases should be counted as FGC. >>> What do you think about it? >>> >>> If it is accepted, I will file it to JBS and will upload webrev. >>> >>> >>> suggested fix: >>> ---------------------- >>> diff -r 8a103ba9a7b2 src/share/vm/gc/g1/g1MonitoringSupport.cpp >>> --- a/src/share/vm/gc/g1/g1MonitoringSupport.cpp Mon Feb 29 22:54:24 >>> 2016 +0900 >>> +++ b/src/share/vm/gc/g1/g1MonitoringSupport.cpp Tue Mar 01 23:43:30 >>> 2016 +0900 >>> @@ -103,7 +103,7 @@ >>> // name "collector.1". In a generational collector this would be the >>> // old generation collection. >>> _full_collection_counters = >>> - new CollectorCounters("G1 stop-the-world full collections", 1); >>> + new CollectorCounters("G1 stop-the-world phase", 1); >>> >>> // timer sampling for all counters supporting sampling only update the >>> // used value. See the take_sample() method. G1 requires both used and >>> diff -r 8a103ba9a7b2 src/share/vm/gc/g1/vm_operations_g1.cpp >>> --- a/src/share/vm/gc/g1/vm_operations_g1.cpp Mon Feb 29 22:54:24 >>> 2016 +0900 >>> +++ b/src/share/vm/gc/g1/vm_operations_g1.cpp Tue Mar 01 23:43:30 >>> 2016 +0900 >>> @@ -230,6 +230,8 @@ >>> G1CollectedHeap* g1h = G1CollectedHeap::heap(); >>> GCTraceTime(Info, gc) t(_printGCMessage, g1h->gc_timer_cm(), >>> GCCause::_no_gc, true); >>> IsGCActiveMark x; >>> + SvcGCMarker sgcm(SvcGCMarker::OTHER); >>> + TraceCollectorStats tcs(g1h->g1mm()->full_collection_counters()); >>> _cl->do_void(); >>> } >>> >>> ---------------------- >>> >>> >>> Thanks, >>> >>> Yasumasa >>> >>> >>
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