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From George Timoshenko <george.timoshe...@gmail.com>
Subject Re: [drlvm][jvmti] Profiling support - Compiled Method Load event
Date Mon, 11 Dec 2006 03:37:39 GMT
Egor Pasko wrote:
> On the 0x237 day of Apache Harmony George Timoshenko wrote:
>> Egor Pasko wrote:
>>> On the 0x236 day of Apache Harmony George Timoshenko wrote:
>>>> Egor Pasko wrote:
>>>>> On the 0x235 day of Apache Harmony George Timoshenko wrote:
>>>>>> Eugene,
>>>>>>
>>>>>> I've answered in JIRA:
>>>>>>
>>>>>> https://issues.apache.org/jira/browse/HARMONY-2145#action_12455313
>>>>>>
>>>>>> (Summary: Everything is OK)
>>>>>>
>>>>>> For this particular testcase it is possible. But there is a general
>>>>>> problem:
>>>>>>
>>>>>> Code layout may be quite unordered. (It mostly depends on hottness,
>>>>>> not the instructions<->method relations) So a method (say A)
body
>>>>>> can be layouted at two (or more) unsuccessive regions.  And the
>>>>>> regeion between them can belong to some another method (say B). And
>>>>>> B is _not_ inlined into A.
>>>>> That is essential, an inlined method can be separated in
>>>>> non-contiguous regions for performance during CFG alignment. IMHO, we
>>>>> should register several code blocks for the same inlined method (if
>>>>> the method's code was split into parts) through the
>>>>> compiled_method_load(...) interface. This can be done completely on
>>>>> the JIT side.
>>>>> What do you, guys, think?
>>>> No doubts it can be done on the JIT side, but what is the purpose of it?
>>>>
>>>> If there is only one question: "I get instruction, which method does
>>>> it belong to?" it can be answerd easily:
>>>>
>>>> For each method jvmtiAddrLocationMap is reported. And each instruction
>>>> (with particular codeAddress) belongs to the only one such map.
>>>>
>>>> I do not understand the necessity of reporting each piece (a number of
>>>> instructions that goes in a row and belongs to the same method) of a
>>>> method while we are already reporting _each_instruction_ separately.
>>> 1. is reporting _each_instruction_ effective?
>> It is a Spec. requirement.
> 
> could you point the exact line of the spec, please? I cannot find it
> :(

It is mentioned in HARMONY-2145 description:

http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#CompiledMethodLoad 


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