Hi, under rare circumstances, we experienced a massive timing overflow of a cyclical DSR. It turned out to be an issue with JFFS2, occurring after a system reboot if long files had been written to the filesystem before.
I found that the issue was only caused by JFFS2's malloc-ecos.c: jffs2_free_full_dnode() By using an oscilloscope, I could see that after the ISR was served, the DSR was delayed, just because free() was called by jffs2_free_full_dnode(). More precisely, the CPU time was spent in memalloc's mvarimpl.inl: Cyg_Mempool_Variable_Implementation::insert_free_block() At first I thought it was a locking issue within JFFS2. But in the end I could not see any scheduler locks which might have caused it. I now have indications, that it could be a general issue with free(). A call to free() from even a low priority thread seems to delay DSR execution after the ISR! The allocator is compiled to be thread-safe, but in my opinion it would be a major drawback if even a low priority thread could not call free() without delaying a critical DSR. Can someone confirm this behaviour? Is it intended? Many thanks, Peter -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
