Re: Can major re-organization activities of the UBIfs be "deliberately provoked"?

[Artem Bityutskiy <dedekind1@gmail.com>]

On Thu, 2011-07-21 at 09:33 -0400, Atlant Schmidt wrote:
> Folks:
> 
>   We're using the UBIfs with our realtime equipment. We've
>   noticed a behavior where, every so often, the flush-ubifs
>   thread demands very, very large amounts of CPU time, blocking
>   all of our other processes that use the Linux time-sliced
>   scheduler. These bursts come at arbitrary intervals but
>   commonly last ten to fifteen seconds.

If the bursts are probably dues to write-back which is initiated by VFS.
When UBIFS is doing write-back it needs to compress data, it may need to
do GC if there is not space.

First - check if the bursts are indeed about write-back - change the
period of write-back and see. Or type sync and see the utilization. Then
you can play with VFS knobs and lessen the write-back intervals
in /proc.


-- 
Best Regards,
Artem Bityutskiy