2011-09-12 12:46:44     Questions about memory fragmentation

Document created by Aaronwu Employee on Aug 27, 2013
Version 1Show Document
  • View in full screen mode

2011-09-12 12:46:44     Questions about memory fragmentation

Cameron Barfield (UNITED STATES)

Message: 103364   


We have a producted based on the BF537 STAMP design (running a BF536, though). Our next generation product is based on the BF527 EZKIT v2.


We ran into an issue with memory fragmentation on the BF536 based product that we don't see on the BF527 based product (backstory here:   blackfin.uclinux.org/gf/project/uclinux-dist/forum/?_forum_action=ForumMessageBrowse&thread_id=46330&action=ForumBrowse&forum_id=39).


The BF536 based product is running on 2009R1 while the BF527 based product is running on2010R1. As an experiment, I compiled our BF536 application on 2010R1. The memory still fragments. As another experiment, I took the BF527 application and ported it to run on the BF536 on 2010R1 (basically, just changed some of the I/O stuff). The memory still fragments.


I'm curious as to why the same application, on the same distribution and same kernel would cause fragmentation on the BF536 but not on the BF527. Is there some difference in whatever software based psuedo-memory manager (assuming such a thing exists) between the two processors, or is there some fundamental difference in the on-board memory manager mentioned in the datasheets?




2011-09-12 23:08:35     Re: Questions about memory fragmentation

Scott Jiang (CHINA)

Message: 103367   


Because more features are added in kernel so kernel consumes more memory.


You can reference this thread:  blackfin.uclinux.org/gf/project/uclinux-dist/forum/?action=ForumBrowse&forum_id=39&_forum_action=ForumMessageBrowse&thread_id=44832.




2011-09-13 18:36:34     Re: Questions about memory fragmentation

Cameron Barfield (UNITED STATES)

Message: 103374   


Scott, I think you misunderstood my question.


I'm seeing identical fragmentation over time on the BF536 on both the 2009 and 2010 kernels. I do not see fragmentation anywhere near as bad on the BF527 on the 2010 kernel.




2011-09-13 23:11:12     Re: Questions about memory fragmentation

Sonic Zhang (CHINA)

Message: 103376   


536 and 527 has different ramfs size, kernel size, configuration and drivers. They may allocate different memory and result in different level of fragmentation at run time.




2011-09-16 17:32:29     Re: Questions about memory fragmentation

Cameron Barfield (UNITED STATES)

Message: 103418   


Can you narrow that down a bit, from the standpoint of a 537 STAMP vs. a 527 EZ-KIT? Shouldn't the same kernel on both CPUs handle memory management the same way?




2011-09-18 22:12:28     Re: Questions about memory fragmentation

Aaron Wu (CHINA)

Message: 103441   


It's not only your application that are consuming memory, there are lots of them, for the drivers it's also true. Basically you need to optimize the memory usage of your system, please search"nommu" in our document wiki, there might be something usesful.