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fflush vs WRITE_THROUGH for mfs

Question asked by Nathan Kohler on Jul 12, 2014
Latest reply on Jul 18, 2014 by soledad


I am using 52259 with mqx 4.0.1.  I was originally doing an fprintf followed by an fflush for every write to a file.  I am doing a write every 50ms.  After several hours of run-time, my USB device just randomly detaches mid write and creates an unhandled exception.  I thought maybe the fflush was causing it, so I tried to get rid of that and change to using

 

param = MFS_WRITE_THROUGH_CACHE;

(usb_fs_ptr->FS_FD_PTR, IO_IOCTL_SET_WRITE_CACHE_MODE, &param);

 

For some reason now the writes to file are taking almost 10x longer than they were when I was using fflush.  Any ideas why?  Is that normal?

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