On Tue, 13 Aug 2024 16:03:16 GMT, Roman Kennke wrote:
>> I tried the following (see diff below) and it shows about a 5-10% regression
>> in most the `LockUnlock.testInflated*` micros. Also tried with just
>> `num_unrolled = 1` saw the same regression. Maybe there was some other
>> pattern you
On Tue, 13 Aug 2024 12:57:23 GMT, Axel Boldt-Christmas
wrote:
>> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 674:
>>
>>> 672:
>>> 673: // Search for obj in cache.
>>> 674: bind(loop);
>>
>> Same loop transformation would be possible here.
>
> I tried the following (see diff
On Mon, 12 Aug 2024 14:37:50 GMT, Axel Boldt-Christmas
wrote:
>> This is a really good suggestion and might help a lot with the performance
>> problems that we see with the table with heavily contended locking. I think
>> we should change this in a follow-on patch (which I'll work on).
>
> I
On Tue, 23 Jul 2024 14:27:34 GMT, Coleen Phillimore wrote:
>> src/hotspot/share/runtime/lightweightSynchronizer.cpp line 105:
>>
>>> 103: };
>>> 104:
>>> 105: class LookupMonitor : public StackObj {
>>
>> I'm not understanding why we need this little wrapper class.
>
> It's a two way looku
On Tue, 23 Jul 2024 16:36:18 GMT, Coleen Phillimore wrote:
>> src/hotspot/share/runtime/lightweightSynchronizer.cpp line 102:
>>
>>> 100: assert(*value != nullptr, "must be");
>>> 101: return (*value)->object_is_cleared();
>>> 102: }
>>
>> The `is_dead` functions seem oddly plac
On Tue, 23 Jul 2024 13:19:02 GMT, Coleen Phillimore wrote:
>> src/hotspot/share/runtime/lightweightSynchronizer.cpp line 62:
>>
>>> 60: class ObjectMonitorWorld : public CHeapObj {
>>> 61: struct Config {
>>> 62: using Value = ObjectMonitor*;
>>
>> Does this alias really help? We don't st
On Tue, 23 Jul 2024 20:21:05 GMT, Coleen Phillimore wrote:
>> Only legacy locking uses the displaced header, I believe, which isn't clear
>> in this code at all. This seems like a fix. We should probably assert that
>> only legacy locking uses this field as a displaced header.
>
> Update: yes
On Tue, 16 Jul 2024 12:36:08 GMT, Roman Kennke wrote:
>> Axel Boldt-Christmas has updated the pull request incrementally with 10
>> additional commits since the last revision:
>>
>> - Remove try_read
>> - Add explicit to single parameter constructors
>> - Remove superfluous access specifier
On Tue, 23 Jul 2024 13:20:27 GMT, Coleen Phillimore wrote:
>> src/hotspot/share/runtime/lightweightSynchronizer.cpp line 77:
>>
>>> 75: using ConcurrentTable = ConcurrentHashTable>> MEMFLAGS::mtObjectMonitor>;
>>> 76:
>>> 77: ConcurrentTable* _table;
>>
>> So you have a class ObjectMonitor
On Wed, 17 Jul 2024 06:48:03 GMT, David Holmes wrote:
>> Axel Boldt-Christmas has updated the pull request incrementally with 10
>> additional commits since the last revision:
>>
>> - Remove try_read
>> - Add explicit to single parameter constructors
>> - Remove superfluous access specifier
On Tue, 23 Jul 2024 13:12:23 GMT, Coleen Phillimore wrote:
>> src/hotspot/share/runtime/deoptimization.cpp line 1641:
>>
>>> 1639: assert(fr.is_deoptimized_frame(), "frame must be
>>> scheduled for deoptimization");
>>> 1640: if (LockingMode == LM_LEGACY) {
>>> 1641:
On Thu, 18 Jul 2024 11:30:27 GMT, Roman Kennke wrote:
>> Axel Boldt-Christmas has updated the pull request incrementally with 10
>> additional commits since the last revision:
>>
>> - Remove try_read
>> - Add explicit to single parameter constructors
>> - Remove superfluous access specifier
On Wed, 17 Jul 2024 06:40:31 GMT, David Holmes wrote:
>> src/hotspot/share/runtime/basicLock.hpp line 46:
>>
>>> 44: // Used as a cache the ObjectMonitor* used when locking. Must either
>>> 45: // be nullptr or the ObjectMonitor* used when locking.
>>> 46: volatile uintptr_t _metadata;
>>
On Wed, 17 Jul 2024 06:35:34 GMT, David Holmes wrote:
>> Axel Boldt-Christmas has updated the pull request incrementally with 10
>> additional commits since the last revision:
>>
>> - Remove try_read
>> - Add explicit to single parameter constructors
>> - Remove superfluous access specifier
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
On Wed, 17 Jul 2024 06:39:14 GMT, David Holmes wrote:
>> Axel Boldt-Christmas has updated the pull request incrementally with 10
>> additional commits since the last revision:
>>
>> - Remove try_read
>> - Add explicit to single parameter constructors
>> - Remove superfluous access specifier
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
On Tue, 16 Jul 2024 12:37:43 GMT, Roman Kennke wrote:
>> Axel Boldt-Christmas has updated the pull request incrementally with 10
>> additional commits since the last revision:
>>
>> - Remove try_read
>> - Add explicit to single parameter constructors
>> - Remove superfluous access specifier
On Mon, 15 Jul 2024 00:50:30 GMT, Axel Boldt-Christmas
wrote:
>> When inflating a monitor the `ObjectMonitor*` is written directly over the
>> `markWord` and any overwritten data is displaced into a displaced
>> `markWord`. This is problematic for concurrent GCs which needs extra care or
>> l
> When inflating a monitor the `ObjectMonitor*` is written directly over the
> `markWord` and any overwritten data is displaced into a displaced `markWord`.
> This is problematic for concurrent GCs which needs extra care or looser
> semantics to use this displaced data. In Lilliput this data als
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