2010-06-21 09:58:39     Is memory fragmentation a real issue?

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2010-06-21 09:58:39     Is memory fragmentation a real issue?

Gilles Ganault (FRANCE)

Message: 90507   




I was wondering if, in practice, applications running on MMU-less CPUs like Blackfin show real issues with memory fragmentation, or if it's mostly theoretical?


If that's the case, and the application can't be rewritten to handle memory itself, is there eg. a daemon that could watch for fragmentation and clean things up or some other solution?


I'm concerned that running Asterisk on a Blackfin CPU would require the user to reboot their appliance often as a work-around.


Thank you.




2010-06-21 11:39:26     Re: Is memory fragmentation a real issue?

Mike Frysinger (UNITED STATES)

Message: 90513   


it depends on the application.  if it continually does a lot of malloc/free operations, some of which it keeps and some of which it holds on to, it will fragment memory over time.  or if it tries to do really large allocations over time and releases them, it'll hit a wall quickly.


if it's a largely stable memory foot print, then fragmentation wont be too much of a problem.


there is nothing a daemon could do to alleviate the issue.  a nommu system does not allow allocated chunks of memory to be shuffled around.  the kernel is already doing just about as much as it can to defragment things on the fly as memory is released.