harmony-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Egor Pasko <egor.pa...@gmail.com>
Subject Re: [drlvm][jvmti] Profiling support - Compiled Method Load event
Date Tue, 05 Dec 2006 09:52:29 GMT
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?
2. VM may want to restore the whole inline tree. How would you do that
   with per-instruction notifications?
3. Guys, did you try RI and look how it behaves? Does it report each
   instruction separately? I doubt so. Let's make it as close to RI as
   possible (for compatibility reasons). I should not be difficult.

-- 
Egor Pasko


Mime
View raw message