On Wed, Sep 03, 2014 at 10:01:58AM +1000, NeilBrown wrote:

Do we still need maximums at all?

I don't think we do.  At least on any system I work with I have to
increase them to get good performance without any adverse effect on
throttling.

So can we just remove the limit on max_sectors and the RAID5 stripe cache
size?  I'm certainly keen to remove the later and just use a mempool if the
limit isn't needed.
I have seen reports that a very large raid5 stripe cache size can cause
a reduction in performance.  I don't know why but I suspect it is a bug that
should be found and fixed.

Do we need max_sectors ??

I'll send a patch to remove it and watch for the fireworks..