[GAP Forum] halfing pool size

[Benjamin Sambale]

Thanks Max!

After using "-s 2048m" the message disappears. Some additional info: my 
"max memory size" is "unlimited". However, I "only" have 4GB memory 
which is partly shared by the graphic card I guess. Now GAP starts even 
faster :-)

Best wishes,
Benjamin

Am 27.07.2012 12:17, schrieb Max Neunhoeffer:
> Dear Benjamin,
>
> thanks for your email. What happens is the following: With GAP 4.5 the
> memory allocation is done in a different way by default. GAP uses mmap
> to allocate 4GB as a "pool" but only uses the beginning of it, such
> that the memory is actually not physically used.
>
> The message "halfing pool size" happens, if this allocation does not
> work, because then GAP tries to half the pool until the allocation
> goes through.
>
> If you get the message once, this means that your OS grants GAP 2GB
> but not 4GB. Is it possible that you have set a resource limit on the
> main memory usage in your OS?
>
> Try "ulimit -a" and look under "max memory size".
>
> You can use GAP's "-s" option to set the pool size to something
> different or use "-s 0" to go the old allocation method.
>
> Cheers,
>    Max.
>
> On Fri, Jul 27, 2012 at 12:01:29PM +0200, Benjamin Sambale wrote:
>> Dear Max,
>>
>> I use GAP 4.5.5 on arch linux 64 bit. For creating the workspace I
>> used the following options (together with the script
>> CreateWorkspace):
>>
>> -m 2048m -T -l "$GAP_DIR" "$@"
>>
>> For using the workspace I start GAP with:
>>
>> -L /usr/local/gap4r5/bin/wsgap4 -T -l "$GAP_DIR" "$@"
>>
>> I'm not sure if it's still necessary to pass the "-T", but this
>> should be irrelevant.
>>
>> Thanks,
>> Benjamin
>>
>> Am 27.07.2012 11:42, schrieb Max Neunhoeffer:
>>> Dear Benjamin,
>>>
>>> just a quick question, are you working on Windows or on what operating
>>> system?
>>> How do you exactly start up GAP? In particular the memory related
>>> options are interesting.
>>>
>>> Best regards,
>>>    Max.
>>> On Fri, Jul 27, 2012 at 10:22:06AM +0200, Benjamin Sambale wrote:
>>>> Dear forum,
>>>>
>>>> every time I start GAP I get the message: "gap: halfing pool size."
>>>> Does it mean I allocate to much memory (actually 2GB out of 4GB)?
>>>> Btw, I load a workspace usually, but this message does not depend on
>>>> that. I found nothing concerning this topic online. And for some
>>>> reasons it never appeared on my office machine.
>>>>
>>>> Thanks,
>>>> Benjamin
>>>>
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