RFR(S): 7185699: G1: Prediction model discrepancies

John Cuthbertson john.cuthbertson at oracle.com
Tue Jul 24 23:03:53 UTC 2012

Hi Azeem,

Thanks for looking at the code. We don't need a closing quote because 
SIZE_FORMAT is a macro already - what it expands to provides the closing 
quote, e.g.:

#define SIZE_FORMAT        "%" PRIuPTR


#define PRIuPTR                 "u"

The definition of ergo_format_bytes above gets the closing quote from 
the " bytes" string.



On 7/24/2012 3:36 PM, Azeem Jiva wrote:
> John,
>   Looks mostly good, but shouldn't the #define in g1ErgoVerbose.hpp 
> have a closing quote(")?
> Azeem Jiva
> @javawithjiva
> On 07/24/2012 01:15 PM, John Cuthbertson wrote:
>> Hi Everyone,
>> Can I have a couple of volunteers to review the changes for this CR? 
>> The webrev can be found at: 
>> http://cr.openjdk.java.net/~johnc/7185699/webrev.0/.
>> Background:
>> While I was going through the code for the current mixed GC policy 
>> and the code that adds non-young regions to the collection set, I 
>> found a couple of minor bugs associated with the prediction code. The 
>> first was the calculation of the number of unprocessed dirty card at 
>> the start of the GC - this was using routines that return a number of 
>> bytes rather than the number of entries. As a result we were vastly 
>> overestimating the base pause time. The second was in the code that 
>> calculates the GC efficiency of a non-young region. The GC efficiency 
>> of a region is calculated at the end of marking. The code, however, 
>> was using the wrong routine to predict the number of cards for a 
>> given RSet length. It was using the data collected for young GCs when 
>> it should have been using the data collected for mixed GCs.
>> The other changes are minor cleanups. These help to slightly increase 
>> the amount of inlining with the Solaris Studio compiler and save an 
>> iteration over the collection set.
>> Testing:
>> Dacapo2006 with Ergonomic output enabled; Dacapo2006 with 
>> PrintLivenessInfo enabled (before and after); GC test suite with 
>> verification; jprt.
>> Thanks,
>> JohnC
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