What should VM writeback timeout be set to for a laptop?

Solution 1:

The larger the dirty writeback setting the longer dirty pages sit in memory before being flushed out to disk. The downside is that this increases the window of opportunity for losing data if you lose power since there will be probably more dirty pages sitting in memory and not flushed out.

Solution 2:

Actually you don't need to set dirty_writeback timeout to more than 6000 centisec, but rather to less. At least for Powertop to smile: It seems Powertop checks for vm.dirty_writeback = an *exact* value of 1500 csec (15 sec). You can check by setting it to this value and look back at the powertop screen. Other than that, @Colin Ian King said it clear on the data loss widening window with higher timeouts.