how to flush the file writes to SD more frequently ?

5883 · 03-20-2014, 03:32 PM

We read/write files in SD card a lot, basically keeping on doing file IO.
During power lost, we found a lot of times files lost the latest changes.
There're too many places to change in the code if we want to call sync().

So what's the linux config to shrink the file write buffer size, so that writes can be flushed into SD more often ?

Thanks !

smallpond · 03-20-2014, 04:48 PM

You could mount with the sync option, which means writes won't be buffered at all.
You could also lower vm.dirty_background_ratio and vm.dirty_ratio, or reduce vm.dirty_expire_centisecs either of which would affect all disk cache.

5883 · 03-20-2014, 05:24 PM

we're using ext4 ordered mode now, if use the mount option (writeback mode) you mentioned, the problem is there won't be journaling, if kernel file etc. gets corrupted, no way for FS to fix it ?

will try the other options, thanks !

Quote:

Originally Posted by smallpond

You could mount with the sync option, which means writes won't be buffered at all.
You could also lower vm.dirty_background_ratio and vm.dirty_ratio, or reduce vm.dirty_expire_centisecs either of which would affect all disk cache.