RFR(two-liner): 8212707: GlobalCounter padding is too optimistic (original) (raw)

Doerr, Martin martin.doerr at sap.com
Tue Oct 23 09:04:44 UTC 2018

Hi Robbin,

Since there is only one instance, I'll skip that. (In a non-integrated draft version of GlobalCounter the PaddedCounter was used in Thread also, therefore size did matter) Ok. That's fine.

Thanks, Martin

-----Original Message----- From: Robbin Ehn <robbin.ehn at oracle.com> Sent: Dienstag, 23. Oktober 2018 11:00 To: Doerr, Martin <martin.doerr at sap.com>; Claes Redestad <claes.redestad at oracle.com>; hotspot-runtime-dev at openjdk.java.net Subject: Re: RFR(two-liner): 8212707: GlobalCounter padding is too optimistic

Hi Martin,

On 10/22/18 4:05 PM, Doerr, Martin wrote:

Hi Robbin,

thanks for fixing.

Thanks!

You could also use "DEFINEPADMINUSSIZE(0, DEFAULTCACHELINESIZE, sizeof(volatile uintx));" as pre-padding if you want to minimize it.

Since there is only one instance, I'll skip that. (In a non-integrated draft version of GlobalCounter the PaddedCounter was used in Thread also, therefore size did matter)

/Robbin

Best regards, Martin

-----Original Message----- From: hotspot-runtime-dev <hotspot-runtime-dev-bounces at openjdk.java.net> On Behalf Of Robbin Ehn Sent: Montag, 22. Oktober 2018 13:15 To: Claes Redestad <claes.redestad at oracle.com>; hotspot-runtime-dev at openjdk.java.net Subject: Re: RFR(two-liner): 8212707: GlobalCounter padding is too optimistic Thanks Claes! /Robbin On 10/22/18 1:18 PM, Claes Redestad wrote: Looks good to me, and as you imply in the comments the DEFAULTCACHELINESIZE should be 64 on x8664

/Claes On 2018-10-22 13:06, Robbin Ehn wrote: Hi all, please review.

We should not divide DEFAULTCACHELINESIZE by 2. More info in issue: https://bugs.openjdk.java.net/browse/JDK-8212707 Code: below Sanity with T1. Thanks, Robbin diff -r bca2b63dd839 src/hotspot/share/utilities/globalCounter.hpp --- a/src/hotspot/share/utilities/globalCounter.hpp    Mon Oct 22 14:08:07 2018 +0800 +++ b/src/hotspot/share/utilities/globalCounter.hpp    Mon Oct 22 11:48:17 2018 +0200 @@ -48,1 +48,1 @@ -    DEFINEPADMINUSSIZE(0, DEFAULTCACHELINESIZE/2, 0); +    DEFINEPADMINUSSIZE(0, DEFAULTCACHELINESIZE, 0); @@ -50,1 +50,1 @@ -    DEFINEPADMINUSSIZE(1, DEFAULTCACHELINESIZE/2, sizeof(volatile uintx)); +    DEFINEPADMINUSSIZE(1, DEFAULTCACHELINESIZE, sizeof(volatile uintx));

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