From: abhishek desai <abhi00@gmail.com>
To: java@gcc.gnu.org
Cc: Andrew Haley <aph@redhat.com>
Subject: Re: Using libgcj with different memory management library.
Date: Mon, 08 Jun 2009 09:43:00 -0000 [thread overview]
Message-ID: <898285d30906080243o70b109a0g54a6b3b00a87f4d2@mail.gmail.com> (raw)
In-Reply-To: <4A2CD546.7030603@redhat.com>
> I don't understand how this can work. The gc is a memory manager; how
> can it use some other memory manager to do its own work? You'll have
> to explain a little more.
From what I understand GC uses GC_unix_get_mem to allocate memory
which calls mmap on /dev/zero on my system. This memory is managed by
GC for object allocation and also for GC internal working. I hope this
is correct. What I want to do is replace the mmap with my_malloc call
which will return a pointer to the allocated memory. my_malloc will
allocate memory from an internal fixed memory pool.
On Mon, Jun 8, 2009 at 2:39 PM, Andrew Haley<aph@redhat.com> wrote:
> abhishek desai wrote:
>
>> 1. As per my understanding libgcj uses boehm garbage collector for
>> memory allocations. Are there any allocations in libgcj which are
>> not routed to the garbage collector ? specially the parts of the
>> library written in C++. From what I understand is that the memory
>> allocated with the 'new' operator are routed to the gc .
>
> Not exactly. If you have a Java class, i.e. one which inherits from
> java.lang.Object, then its new uses the GC.
>
>> Is it necessary that the class of object being allocated should be
>> derived from the 'object' class for it to be allocated on the gc ?
>> or all the allocations with new get routed to gc ?
>> http://gcc.gnu.org/onlinedocs/gcj/Object-allocation.html#Object-allocation
>
> Yes, it is. Of course, you can always overload new in your own classes
> to use the Boehm gc, evernif they don't derive from Object. You'll
> have to make sure they're marked correctly, though.
>
>> 2. I have a memory manager which allocates memory from a specific
>> memory pool. I want to port boehm gc to use this memory manager for
>> its allocations.
>
> I don't understand how this can work. The gc is a memory manager; how
> can it use some other memory manager to do its own work? You'll have
> to explain a little more.
>
>> Can someone give me some pointers as to where I can make the
>> necessary modifications ? I can see the gcconfig.h and os_dep.c is
>> the file containing the final system memory allocation calls. Is
>> there some other place I need to look at ? Are there any tricky
>> issues I need to look at while doing the porting ?
>
> You'll need to the gc just to scan your memory pool, or also manage
> it? Doing the latter will be hard, the former easy.
>
> Andrew.
>
>
next prev parent reply other threads:[~2009-06-08 9:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-08 7:06 abhishek desai
2009-06-08 9:09 ` Andrew Haley
2009-06-08 9:43 ` abhishek desai [this message]
2009-06-08 9:45 ` Andrew Haley
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