RFR(XS): 8204135: jtreg: Fix failing RTM test TestUseRTMXendForLockBusy

[Gustavo Romero]

Hi Igor,

On 06/15/2018 10:12 AM, Lindenmaier, Goetz wrote:
> I had a look at your fix. As I understand the test it's just
> what was intended to do. Also, it fixed the test in our runs.
> 
> Reviewed.
> 
> I would volunteer to sponsor this.

Goetz reviewed the change. Is it OK to be pushed?


Thanks.

Best regards,
Gustavo

> Best regards,
>    Goetz.
> 
>> -----Original Message-----
>> From: Gustavo Romero [mailto:gromero at linux.vnet.ibm.com]
>> Sent: Donnerstag, 31. Mai 2018 04:05
>> To: hotspot-compiler-dev at openjdk.java.net; igor.ignatyev at oracle.com
>> Cc: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; Doerr, Martin
>> <martin.doerr at sap.com>
>> Subject: RFR(XS): 8204135: jtreg: Fix failing RTM test
>> TestUseRTMXendForLockBusy
>>
>> Hi,
>>
>> Could the following change be reviewed please?
>>
>> webrev: http://cr.openjdk.java.net/~gromero/8204135/v1
>> bug   : https://bugs.openjdk.java.net/browse/JDK-8204135
>>
>> It fixes currently failing RTM test "TestUseRTMXendForLockBusy" by
>> changing
>> in which cases UseRTMForStackLocks flags must be enabled/disabled.
>>
>> I could not track down on the timeline when exactly that test stopped to
>> pass, however my understanding is that if inflateMonitor is 'false' that
>> should /not/ imply that UseRTMForStackLocks is also 'false'. Thus I
>> understand that for this particular test if inflated monitors are used,
>> then UseRTMForStackLocks has to be disabled, i.e. 'false'. On the other
>> hand, if inflated monitors are /not/ used, then UseRTMForStackLocks must
>> be
>> enabled.
>>
>> Currently the test is failing for the following cases where inflateMonitor
>> is 'false', because it implies that UseRTMForStackLocks is disabled and so
>> no abort statistics is generated (which is correct from the JVM's
>> perspective):
>>
>>           // stack lock, xabort on lock busy
>>           verifyXendForLockBusy(false, false);
>>           // stack lock, xend on lock busy
>>           verifyXendForLockBusy(false, true);
>>
>> In other words, "stack lock" case should imply UseRTMForStackLocks = 'true',
>> not 'false'.
>>
>> Cases:
>>           // inflated lock, xabort on lock busy
>>           verifyXendForLockBusy(true, false);
>>           // inflated lock, xend on lock busy
>>           verifyXendForLockBusy(true, true);
>>
>> are not failing because UseRTMForStackLocks = 'true' and they will generate
>> proper abort statistics when  +UseRTMXendForLockBusy ('xend' is used to
>> finish the transaction) or when -UseRTMXendForLockBusy ('xabort' is used
>> to finish the transaction).
>>
>> So, in summing up: (a) inflated lock cases are not being tested correctly
>> (since UseRTMForStackLocks is always enabled) and (b) stack lock cases are
>> failing because UseRTMForStackLocks is always disabled.
>>
>> @Igor, it's a long time ago, but maybe you recall some details on that
>> test... :-)
>>
>>
>> Thank you.
>>
>> Best regards,
>> Gustavo
>