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From Egor Pasko <egor.pa...@gmail.com>
Subject Re: [drlvm][em] Value-profiling implementation is avaible.
Date Tue, 31 Oct 2006 11:23:30 GMT
On the 0x213 day of Apache Harmony Mikhail Fursov wrote:
> Yuri,
> I support Egor in the most of the points. Your code is conceptually OK and
> is fitted into EM in the right way, but you can't get your code commited if
> you do not check it on Linux and Windows.
> On 31 Oct 2006 14:35:02 +0600, Egor Pasko <egor.pasko@gmail.com> wrote:
> >
> > * you do one global lock (profilesLock), that would be a *real crawl* :)
> >   Profiling is method-wise, I'd suggest a lock per method. How is
> >   that?
> Agree with Egor.
> In the edge profiler I use only one global lock to keep profiles collection
> safe when adding new profiles.
> So the one global lock is OK in this case. But as I see Yuri uses the lock
> even for insertion of new values. Do you really need this lock here?

The lock is not necessary if you update a single word. In case of
incrementing counters no synch is OK (minor inaccuracy), but here we
are updating an std::map, which is dangerous.

> * do you have an .emprofile to test your implementation? Would have
> >   been great!
> >
> > * why EM_PCTYPE updated, but ProfileType left as-is? is it intentional?
> ProfileType is a JIT wrapper for EM types. Yuri's patch does not contain any
> JIT changes. So this is  a TODO: add value profiling support to the JIT.
> * why a value is a mere 'int'? what about pointer profiling? it is different
> >   on IA-32 and x86_64. How would you write a portable piece of
> >   profiler? Not nerdy, just curious :)
> Reasonable question. I think value profiler should not care(at least the
> first version) about the semantics of data it collects. int32 is enough to
> profile type information for methods. int64 sized values could be added
> latter.

OK, let's discuss it later

Egor Pasko, Intel Managed Runtime Division

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