fflush vs WRITE_THROUGH for mfs

njk909 — Sat, 12 Jul 2014 14:34:24 GMT

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?

Re: fflush vs WRITE_THROUGH for mfs

soledad — Fri, 18 Jul 2014 16:42:06 GMT

Hi Nathan,

Please check the below threads,

MFS Corruption

Howto flush MFS? (Use case: mfs onto ramdisk)

Have a great day,
Sol

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topic fflush vs WRITE_THROUGH for mfs in MQX Software Solutions

fflush vs WRITE_THROUGH for mfs

Re: fflush vs WRITE_THROUGH for mfs