RFR: 8202140: TLAB logging is not correct for G1

Stefan Johansson stefan.johansson at oracle.com
Tue Apr 24 08:32:07 UTC 2018


Hi Thomas,

On 2018-04-23 15:42, Thomas Schatzl wrote:
> Hi,
> 
> On Mon, 2018-04-23 at 14:57 +0200, Stefan Johansson wrote:
>> Hi,
>>
>> Please review this small change to make TLAB logging more correct,
>> especially for collectors using regions.
>>
>> JBS: https://bugs.openjdk.java.net/browse/JDK-8202140
>> Webrev: http://cr.openjdk.java.net/~sjohanss/8202140/00/
>>
>> Summary
>> The current TLAB logging is not completely correct for G1 and other
>> collectors using regions. The logging in
>> ThreadLocalAllocBuffer::print_stats() expects that the allocated size
>> is: size_t alloc = _number_of_refills * _desired_size;
>>
>> For each region in G1 the last TLAB might be smaller then
>> _desired_size and therefor we need to add a separate value to account
>> the actual allocated size.
> 
>    looks good to me.
> 
> Maybe please fix the indentation of
> ThreadLocalAllocBuffer::initialize_statistics().
> 
Thanks for the review, I will add this before pushing:
===
diff --git a/src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp 
b/src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp
--- a/src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp
+++ b/src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp
@@ -157,12 +157,12 @@
  }

  void ThreadLocalAllocBuffer::initialize_statistics() {
-    _number_of_refills = 0;
-    _fast_refill_waste = 0;
-    _slow_refill_waste = 0;
-    _gc_waste          = 0;
-    _slow_allocations  = 0;
-    _allocated_size    = 0;
+  _number_of_refills = 0;
+  _fast_refill_waste = 0;
+  _slow_refill_waste = 0;
+  _gc_waste          = 0;
+  _slow_allocations  = 0;
+  _allocated_size    = 0;
  }

  void ThreadLocalAllocBuffer::fill(HeapWord* start,
===

Cheers,
Stefan

> Thanks,
>    Thomas
> 


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