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

[Doerr, Martin]

Hi Robbin,

thanks for fixing.

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

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 DEFAULT_CACHE_LINE_SIZE 
> should be 64 on x86_64
> 
> /Claes
> 
> On 2018-10-22 13:06, Robbin Ehn wrote:
>> Hi all, please review.
>>
>> We should not divide DEFAULT_CACHE_LINE_SIZE 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 @@
>> -    DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE/2, 0);
>> +    DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, 0);
>> @@ -50,1 +50,1 @@
>> -    DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE/2, sizeof(volatile uintx));
>> +    DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile uintx));
>