RFR: JDK-8086056: ParNew: auto-tune ParGCCardsPerStrideChunk

Tony Printezis tprintezis at twitter.com
Wed Jul 1 22:05:05 UTC 2015

Latest changes, as discussed with Bengt and Thomas,



On June 26, 2015 at 9:37:45 AM, Thomas Schatzl (thomas.schatzl at oracle.com) wrote:

Hi Tony,  

On Fri, 2015-06-26 at 09:30 -0400, Tony Printezis wrote:  

> >  
> >  
> > The JEP says:  
> >  
> > "The range and constraints checks are done every time a flag  
> > changes, as well as late in the JVM initialization routine (i.e., in  
> > init_globals() after stubRoutines_init2()) at the time when all  
> > flags have their final values set. We will continue to check the  
> > manageable flags as long as the JVM runs."  
> >  
> > I haven't actively been using this myself, but I assume that the  
> > constraints will be checked every time a managaeble flag is changed  
> > and that the one trying to change it will get an error reported back  
> > if they try to change it in an invalid way.  
> >  
> > I'm copying Gerard on this email. He has built this support and can  
> > surely answer the details.  
> Hi, thanks. I’ll definitely look at it and change the code  
> appropriately. BTW, has the change been integrated into the hs gc repo  
> yet? (I don’t see it so I assume it hasn't.)  

You overlooked that a week or two ago we started to try out merging the  
hs-rt and hs-gc repos to test whether doing so is beneficial in terms of  
maintenance etc.  

So the hs-gc repo is currently discontinued. Please rebase your changes  
to hs-rt. :)  

> >  
> > Finally, just a heads up. I will be on vacation for the coming three  
> > weeks. I doubt that I will be able to review any new version during  
> > that time. If you get reviews from others I'm perfectly fine with  
> > this being pushed. Depending on how different the changes that you  
> > push are compared to the versions I've reviewed I'll leave it up to  
> > you to decide whether you want to list me as a reviewer or not. I'm  
> > fine either way. It's not a problem to leave me out of the reviewer  
> > list if you are unsure.  
> OK, thanks for letting me know! And enjoy your time off!!!!  

I will take over :)  



Tony Printezis | JVM/GC Engineer / VM Team | Twitter

tprintezis at twitter.com

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