Re: [rvm-research] to utilize methods in syscall

> Dear Robin,
> Using a custom function, I can create an address space with special
> attributes. Now I want to use this address chunk as the nursery space of
> a generational collector.
> I originally, as described in the first mail, want to use the sysCalls
> and VMRequest class. That is, to build the custom function into the
> sysCalls, and use the vmRequest.create(Address address, Extent extent)
> method to map the special address space into the nursery. It doesn't
> work, as you see.
> Then, I am wondering, are there any other ways that I can resort to?
> Thanks.
>
> Regards,
> Liangliang
>
> Robin Garner wrote:
>> Liangliang Tong wrote:
>>
>>> Dear Robin,
>>>
>>> Thanks for your reply.
>>> I am just taking sysMalloc as an example, the actual method I called is
>>> another custom allocation function implemented by myself. This function
>>> applies special characteristics to the allocated memory chunk, which I
>>> hope to use as a nursery space. Rawpagespace does not help.
>>> In this case, what am I supposed to do in order to achieve my target?
>>> Thanks.
>>>
>>>
>> I'm not sure I understand what your target is - perhaps you could use a
>> better example ?
>>
>> I've outlined the steps you need to follow in order to make an arbitrary
>> syscall (and for more details, follow a method like 'dzmmap' through the
>> interface).
>>
>> If you want to implement a new allocator (at the object level), then
>> what you want to do is sub-class Space and Allocator for the global and
>> thread-local components of the allocator.  If you want to change how a
>> Space acquires pages from the OS, then you should create a new
>> PageResource and define or modify a sub-class of Space that uses it.
>>
>> If you need more explanation, please tell us in more detail what it is
>> you're trying to do.
>>
>> Regards,
>> Robin
>>
>>> Regards,
>>> Liangliang
>>>
>>> Robin Garner wrote:
>>>
>>>
>>>> Liangliang Tong wrote:
>>>>
>>>>
>>>>
>>>>> Dear all,
>>>>>
>>>>> In org.mmtk.plan.generational.Gen.java, I want to modify the vmRequest
>>>>> to request for an explicit region of memory, like the following:
>>>>>    private static final VMRequest vmRequest =
>>>>> VMRequest.create(sysCall.sysMalloc(1 << 20),  Extent.fromIntSignExtend(1
>>>>> << 20));
>>>>> correspondingly I add a new import statement:
>>>>>  import static org.jikesrvm.runtime.SysCall.sysCall;
>>>>>
>>>>> Yet when I complied the generational copy plan, it prompts these errors:
>>>>> compile-mmtk:
>>>>>     [javac] Compiling 1 source file to
>>>>> /home/lltong/jikesrvm/target/mmtk/classes
>>>>>     [javac]
>>>>> /home/lltong/jikesrvm/MMTk/src/org/mmtk/plan/crgenerational/CRGen.java:33:
>>>>> package org.jikesrvm.runtime does not exist
>>>>>     [javac] import static org.jikesrvm.runtime.SysCall.sysCall;
>>>>>     [javac]                                   ^
>>>>>     [javac]
>>>>> /home/lltong/jikesrvm/MMTk/src/org/mmtk/plan/crgenerational/CRGen.java:33:
>>>>> static import only from classes and interfaces
>>>>>     [javac] import static org.jikesrvm.runtime.SysCall.sysCall;
>>>>>     [javac] ^
>>>>>     [javac]
>>>>> /home/lltong/jikesrvm/MMTk/src/org/mmtk/plan/crgenerational/CRGen.java:91:
>>>>> cannot find symbol
>>>>>     [javac] symbol  : variable sysCall
>>>>>     [javac] location: class org.mmtk.plan.crgenerational.CRGen
>>>>>
>>>>> Why should this happen? Thanks in advance.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>> Hi Liangliang,
>>>>
>>>> As far as I can see, you are trying to request a 1MB chunk of memory,
>>>> and you don't care where in the heap it is.  Is this right ?
>>>>
>>>>
>>>> MMTk uses the 'Space' class to abstract over various ways to allocate
>>>> memory.  If you simply want a 1MB chunk of raw memory, then you can do
>>>>
>>>>   RawPageSpace mySpace = new RawPageSpace("mySpace", Integer.MAX_VALUE,
>>>> VMRequest.create());
>>>>   Address chunkAddr = mySpace.acquire(1<<(20-LOG_BYTES_IN_PAGE));
>>>>
>>>> If you're using memory as storage for your collector, you should
>>>> probably allocate it in the existing metaDataSpace.  If you're
>>>> allocating it to give to the mutator, you should probably define a new
>>>> space for it.
>>>>
>>>> Note that a VMRequest is simply a way to communicate your virtual memory
>>>> layout requirements to the Space class, and passing it a chunk of
>>>> 'malloc'ed memory doesn't make a great deal of sense.  In fact MMTk
>>>> itself generally takes the place of 'malloc' in the virtual machine.
>>>>
>>>>
>>>> The reason you can't directly call sysMalloc from MMTk is that MMTk
>>>> separates itself from JikesRVM (and its various other host environments)
>>>> via the org.mmtk.vm package (the VM interface).  In order to call a new
>>>> method on the JikesRVM side of the fence you need to:
>>>>
>>>> - Choose an interface class to host the method (eg org.mmtk.vm.Memory)
>>>> - Add an abstract method to the interface class
>>>> - Add a concrete method to the implementation on the VM side of the
>>>> fence (for JikesRVM that is org.jikesrvm.mm.mmtk, in the
>>>> MMTk/ext/vm/jikesrvm directory)
>>>>
>>>> but I think it would generally be a bad idea for you to allocate memory
>>>> for JikesRVM using sysMalloc.
>>>>
>>>> Regards,
>>>> Robin
>>>>
>>>>
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>>>>
>>>>
>>>>
>>>
>>>
>>
>>
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>>
>
>
> --
> Regards,
> Liangliang Tong
>
>
> ------------------------------------------------------------------------------
> Crystal Reports - New Free Runtime and 30 Day Trial
> Check out the new simplified licensing option that enables unlimited
> royalty-free distribution of the report engine for externally facing
> server and web deployment.
> http://p.sf.net/sfu/businessobjects
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