From: Andrew Haley <aph@redhat.com>
To: Bryce McKinlay <bmckinlay@gmail.com>
Cc: Herman ten Brugge <hermantenbrugge@home.nl>,
java@gcc.gnu.org, Tom Tromey <tromey@redhat.com>
Subject: Re: very slow jni code callbacks
Date: Mon, 28 Sep 2009 12:13:00 -0000 [thread overview]
Message-ID: <4AC0A859.2070407@redhat.com> (raw)
In-Reply-To: <7230133d0909280510w1728ce99i1cda1b41fb8f17e5@mail.gmail.com>
Bryce McKinlay wrote:
> On Mon, Sep 28, 2009 at 1:03 PM, Andrew Haley <aph@redhat.com> wrote:
>
>>> When I use oprofile I see at lot of calls to execute_cfa_program
>>> and _Unwind_IteratePhdrCallback.
>> I think this is a bug. I've had a look at the code, and it's in
>> jni.cc: _Jv_JNI_CallAnyVoidMethodV
>>
>> This calls _Jv_GetTypesFromSignature, which in turn iterates though
>> all the class loaders looking up the types of all the arguments.
>> But as far as I can see this is a pointless waste of time: the only
>> use of the type of each argument is to determine whether it's a
>> primitive type or not, and we could certainly have done that when
>> we created the jmethodID. There is a field in the method struct called
>> ffi_arg_types, but I think it isn't used when calling C to Java via JNI.
>
> I think the underlying issue is that jMethodID is typedef'ed to
> libgcj's internal _Jv_Method. It really needs to use something more
> like the interpreter's _Jv_ResolvedMethod or _Jv_JNIMethod so that the
> arg types and return type (and, in fact, the ffi_cif itself) can be
> resolved once and reused.
Well, sure, but it seems to me like this is obvious and almost trivial,
so I don't understand what the problem is. I'm guessing that it's simply
that no-one ever got around to doing it.
Andrew.
next prev parent reply other threads:[~2009-09-28 12:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-27 13:23 Herman ten Brugge
2009-09-28 12:03 ` Andrew Haley
2009-09-28 12:10 ` Bryce McKinlay
2009-09-28 12:13 ` Andrew Haley [this message]
2009-09-28 19:01 ` Tom Tromey
2009-09-28 19:01 ` Tom Tromey
2009-09-28 19:47 ` Herman ten Brugge
2009-09-28 20:13 ` Andrew Haley
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